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.. SPDX-License-Identifier: GPL-2.0
====================
The /proc Filesystem
====================
===================== ======================================= ================
/proc/sys Terrehon Bowden <terrehon@pacbell.net>, October 7 1999
Bodo Bauer <bb@ricochet.net>
2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000
move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009
===================== ======================================= ================
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.. Table of Contents
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0 Preface
0.1 Introduction/Credits
0.2 Legal Stuff
1 Collecting System Information
1.1 Process-Specific Subdirectories
1.2 Kernel data
1.3 IDE devices in /proc/ide
1.4 Networking info in /proc/net
1.5 SCSI info
1.6 Parallel port info in /proc/parport
1.7 TTY info in /proc/tty
1.8 Miscellaneous kernel statistics in /proc/stat
2015-01-23 19:45:05 +03:00
1.9 Ext4 file system parameters
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2 Modifying System Parameters
2009-04-03 03:57:20 +04:00
3 Per-Process Parameters
2012-11-13 05:53:04 +04:00
3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
oom: badness heuristic rewrite
This a complete rewrite of the oom killer's badness() heuristic which is
used to determine which task to kill in oom conditions. The goal is to
make it as simple and predictable as possible so the results are better
understood and we end up killing the task which will lead to the most
memory freeing while still respecting the fine-tuning from userspace.
Instead of basing the heuristic on mm->total_vm for each task, the task's
rss and swap space is used instead. This is a better indication of the
amount of memory that will be freeable if the oom killed task is chosen
and subsequently exits. This helps specifically in cases where KDE or
GNOME is chosen for oom kill on desktop systems instead of a memory
hogging task.
The baseline for the heuristic is a proportion of memory that each task is
currently using in memory plus swap compared to the amount of "allowable"
memory. "Allowable," in this sense, means the system-wide resources for
unconstrained oom conditions, the set of mempolicy nodes, the mems
attached to current's cpuset, or a memory controller's limit. The
proportion is given on a scale of 0 (never kill) to 1000 (always kill),
roughly meaning that if a task has a badness() score of 500 that the task
consumes approximately 50% of allowable memory resident in RAM or in swap
space.
The proportion is always relative to the amount of "allowable" memory and
not the total amount of RAM systemwide so that mempolicies and cpusets may
operate in isolation; they shall not need to know the true size of the
machine on which they are running if they are bound to a specific set of
nodes or mems, respectively.
Root tasks are given 3% extra memory just like __vm_enough_memory()
provides in LSMs. In the event of two tasks consuming similar amounts of
memory, it is generally better to save root's task.
Because of the change in the badness() heuristic's baseline, it is also
necessary to introduce a new user interface to tune it. It's not possible
to redefine the meaning of /proc/pid/oom_adj with a new scale since the
ABI cannot be changed for backward compatability. Instead, a new tunable,
/proc/pid/oom_score_adj, is added that ranges from -1000 to +1000. It may
be used to polarize the heuristic such that certain tasks are never
considered for oom kill while others may always be considered. The value
is added directly into the badness() score so a value of -500, for
example, means to discount 50% of its memory consumption in comparison to
other tasks either on the system, bound to the mempolicy, in the cpuset,
or sharing the same memory controller.
/proc/pid/oom_adj is changed so that its meaning is rescaled into the
units used by /proc/pid/oom_score_adj, and vice versa. Changing one of
these per-task tunables will rescale the value of the other to an
equivalent meaning. Although /proc/pid/oom_adj was originally defined as
a bitshift on the badness score, it now shares the same linear growth as
/proc/pid/oom_score_adj but with different granularity. This is required
so the ABI is not broken with userspace applications and allows oom_adj to
be deprecated for future removal.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-10 04:19:46 +04:00
score
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3.2 /proc/<pid>/oom_score - Display current oom-killer score
3.3 /proc/<pid>/io - Display the IO accounting fields
3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
3.5 /proc/<pid>/mountinfo - Information about mounts
2009-12-15 05:00:05 +03:00
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
2012-06-01 03:26:43 +04:00
3.7 /proc/<pid>/task/<tid>/children - Information about task children
2012-12-18 04:05:14 +04:00
3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
2015-02-12 02:28:31 +03:00
3.9 /proc/<pid>/map_files - Information about memory mapped files
2016-03-18 00:20:54 +03:00
3.10 /proc/<pid>/timerslack_ns - Task timerslack value
2017-02-14 04:42:41 +03:00
3.11 /proc/<pid>/patch_state - Livepatch patch operation state
2019-06-06 04:22:36 +03:00
3.12 /proc/<pid>/arch_status - Task architecture specific information
2009-04-03 03:57:20 +04:00
procfs: add hidepid= and gid= mount options
Add support for mount options to restrict access to /proc/PID/
directories. The default backward-compatible "relaxed" behaviour is left
untouched.
The first mount option is called "hidepid" and its value defines how much
info about processes we want to be available for non-owners:
hidepid=0 (default) means the old behavior - anybody may read all
world-readable /proc/PID/* files.
hidepid=1 means users may not access any /proc/<pid>/ directories, but
their own. Sensitive files like cmdline, sched*, status are now protected
against other users. As permission checking done in proc_pid_permission()
and files' permissions are left untouched, programs expecting specific
files' modes are not confused.
hidepid=2 means hidepid=1 plus all /proc/PID/ will be invisible to other
users. It doesn't mean that it hides whether a process exists (it can be
learned by other means, e.g. by kill -0 $PID), but it hides process' euid
and egid. It compicates intruder's task of gathering info about running
processes, whether some daemon runs with elevated privileges, whether
another user runs some sensitive program, whether other users run any
program at all, etc.
gid=XXX defines a group that will be able to gather all processes' info
(as in hidepid=0 mode). This group should be used instead of putting
nonroot user in sudoers file or something. However, untrusted users (like
daemons, etc.) which are not supposed to monitor the tasks in the whole
system should not be added to the group.
hidepid=1 or higher is designed to restrict access to procfs files, which
might reveal some sensitive private information like precise keystrokes
timings:
http://www.openwall.com/lists/oss-security/2011/11/05/3
hidepid=1/2 doesn't break monitoring userspace tools. ps, top, pgrep, and
conky gracefully handle EPERM/ENOENT and behave as if the current user is
the only user running processes. pstree shows the process subtree which
contains "pstree" process.
Note: the patch doesn't deal with setuid/setgid issues of keeping
preopened descriptors of procfs files (like
https://lkml.org/lkml/2011/2/7/368). We rely on that the leaked
information like the scheduling counters of setuid apps doesn't threaten
anybody's privacy - only the user started the setuid program may read the
counters.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg KH <greg@kroah.com>
Cc: Theodore Tso <tytso@MIT.EDU>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: James Morris <jmorris@namei.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-11 03:11:31 +04:00
4 Configuring procfs
4.1 Mount options
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Preface
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=======
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0.1 Introduction/Credits
------------------------
This documentation is part of a soon (or so we hope) to be released book on
the SuSE Linux distribution. As there is no complete documentation for the
/proc file system and we've used many freely available sources to write these
chapters, it seems only fair to give the work back to the Linux community.
This work is based on the 2.2.* kernel version and the upcoming 2.4.* . I'm
afraid it's still far from complete, but we hope it will be useful. As far as
we know, it is the first 'all-in-one' document about the /proc file system. It
is focused on the Intel x86 hardware, so if you are looking for PPC, ARM,
SPARC, AXP, etc., features, you probably won't find what you are looking for.
It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
additions and patches are welcome and will be added to this document if you
mail them to Bodo.
We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of
other people for help compiling this documentation. We'd also like to extend a
special thank you to Andi Kleen for documentation, which we relied on heavily
to create this document, as well as the additional information he provided.
Thanks to everybody else who contributed source or docs to the Linux kernel
and helped create a great piece of software... :)
If you have any comments, corrections or additions, please don't hesitate to
contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this
document.
The latest version of this document is available online at
2010-07-24 07:51:24 +04:00
http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html
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2010-07-24 07:51:24 +04:00
If the above direction does not works for you, you could try the kernel
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mailing list at linux-kernel@vger.kernel.org and/or try to reach me at
comandante@zaralinux.com.
0.2 Legal Stuff
---------------
We don't guarantee the correctness of this document, and if you come to us
complaining about how you screwed up your system because of incorrect
documentation, we won't feel responsible...
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Chapter 1: Collecting System Information
========================================
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In This Chapter
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---------------
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* Investigating the properties of the pseudo file system /proc and its
ability to provide information on the running Linux system
* Examining /proc's structure
* Uncovering various information about the kernel and the processes running
on the system
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------------------------------------------------------------------------------
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The proc file system acts as an interface to internal data structures in the
kernel. It can be used to obtain information about the system and to change
certain kernel parameters at runtime (sysctl).
First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
show you how you can use /proc/sys to change settings.
1.1 Process-Specific Subdirectories
-----------------------------------
The directory /proc contains (among other things) one subdirectory for each
process running on the system, which is named after the process ID (PID).
The link self points to the process reading the file system. Each process
subdirectory has the entries listed in Table 1-1.
2018-11-05 16:22:05 +03:00
Note that an open a file descriptor to /proc/<pid> or to any of its
contained files or subdirectories does not prevent <pid> being reused
for some other process in the event that <pid> exits. Operations on
open /proc/<pid> file descriptors corresponding to dead processes
never act on any new process that the kernel may, through chance, have
also assigned the process ID <pid>. Instead, operations on these FDs
usually fail with ESRCH.
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.. table :: Table 1-1: Process specific entries in /proc
============= ===============================================================
2007-05-07 01:49:24 +04:00
File Content
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============= ===============================================================
2007-05-07 01:49:24 +04:00
clear_refs Clears page referenced bits shown in smaps output
cmdline Command line arguments
cpu Current and last cpu in which it was executed (2.4)(smp)
cwd Link to the current working directory
environ Values of environment variables
exe Link to the executable of this process
fd Directory, which contains all file descriptors
maps Memory maps to executables and library files (2.4)
mem Memory held by this process
root Link to the root directory of this process
stat Process status
statm Process memory status information
status Process status in human readable form
fs/proc, core/debug: Don't expose absolute kernel addresses via wchan
So the /proc/PID/stat 'wchan' field (the 30th field, which contains
the absolute kernel address of the kernel function a task is blocked in)
leaks absolute kernel addresses to unprivileged user-space:
seq_put_decimal_ull(m, ' ', wchan);
The absolute address might also leak via /proc/PID/wchan as well, if
KALLSYMS is turned off or if the symbol lookup fails for some reason:
static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
unsigned long wchan;
char symname[KSYM_NAME_LEN];
wchan = get_wchan(task);
if (lookup_symbol_name(wchan, symname) < 0) {
if (!ptrace_may_access(task, PTRACE_MODE_READ))
return 0;
seq_printf(m, "%lu", wchan);
} else {
seq_printf(m, "%s", symname);
}
return 0;
}
This isn't ideal, because for example it trivially leaks the KASLR offset
to any local attacker:
fomalhaut:~> printf "%016lx\n" $(cat /proc/$$/stat | cut -d' ' -f35)
ffffffff8123b380
Most real-life uses of wchan are symbolic:
ps -eo pid:10,tid:10,wchan:30,comm
and procps uses /proc/PID/wchan, not the absolute address in /proc/PID/stat:
triton:~/tip> strace -f ps -eo pid:10,tid:10,wchan:30,comm 2>&1 | grep wchan | tail -1
open("/proc/30833/wchan", O_RDONLY) = 6
There's one compatibility quirk here: procps relies on whether the
absolute value is non-zero - and we can provide that functionality
by outputing "0" or "1" depending on whether the task is blocked
(whether there's a wchan address).
These days there appears to be very little legitimate reason
user-space would be interested in the absolute address. The
absolute address is mostly historic: from the days when we
didn't have kallsyms and user-space procps had to do the
decoding itself via the System.map.
So this patch sets all numeric output to "0" or "1" and keeps only
symbolic output, in /proc/PID/wchan.
( The absolute sleep address can generally still be profiled via
perf, by tasks with sufficient privileges. )
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: kasan-dev <kasan-dev@googlegroups.com>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20150930135917.GA3285@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-30 16:59:17 +03:00
wchan Present with CONFIG_KALLSYMS=y: it shows the kernel function
symbol the task is blocked in - or "0" if not blocked.
2010-10-28 02:34:11 +04:00
pagemap Page table
2008-11-10 11:26:08 +03:00
stack Report full stack trace, enable via CONFIG_STACKTRACE
2019-07-12 07:00:10 +03:00
smaps An extension based on maps, showing the memory consumption of
2012-12-18 04:03:13 +04:00
each mapping and flags associated with it
2019-07-12 07:00:10 +03:00
smaps_rollup Accumulated smaps stats for all mappings of the process. This
can be derived from smaps, but is faster and more convenient
numa_maps An extension based on maps, showing the memory locality and
2015-02-13 02:01:05 +03:00
binding policy as well as mem usage (in pages) of each mapping.
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============= ===============================================================
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For example, to get the status information of a process, all you have to do is
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read the file /proc/PID/status::
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2009-06-18 03:26:01 +04:00
>cat /proc/self/status
Name: cat
State: R (running)
Tgid: 5452
Pid: 5452
PPid: 743
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TracerPid: 0 (2.4)
2009-06-18 03:26:01 +04:00
Uid: 501 501 501 501
Gid: 100 100 100 100
FDSize: 256
Groups: 100 14 16
VmPeak: 5004 kB
VmSize: 5004 kB
VmLck: 0 kB
VmHWM: 476 kB
VmRSS: 476 kB
mm, procfs: breakdown RSS for anon, shmem and file in /proc/pid/status
There are several shortcomings with the accounting of shared memory
(SysV shm, shared anonymous mapping, mapping of a tmpfs file). The
values in /proc/<pid>/status and <...>/statm don't allow to distinguish
between shmem memory and a shared mapping to a regular file, even though
theirs implication on memory usage are quite different: during reclaim,
file mapping can be dropped or written back on disk, while shmem needs a
place in swap.
Also, to distinguish the memory occupied by anonymous and file mappings,
one has to read the /proc/pid/statm file, which has a field for the file
mappings (again, including shmem) and total memory occupied by these
mappings (i.e. equivalent to VmRSS in the <...>/status file. Getting
the value for anonymous mappings only is thus not exactly user-friendly
(the statm file is intended to be rather efficiently machine-readable).
To address both of these shortcomings, this patch adds a breakdown of
VmRSS in /proc/<pid>/status via new fields RssAnon, RssFile and
RssShmem, making use of the previous preparatory patch. These fields
tell the user the memory occupied by private anonymous pages, mapped
regular files and shmem, respectively. Other existing fields in /status
and /statm files are left without change. The /statm file can be
extended in the future, if there's a need for that.
Example (part of) /proc/pid/status output including the new Rss* fields:
VmPeak: 2001008 kB
VmSize: 2001004 kB
VmLck: 0 kB
VmPin: 0 kB
VmHWM: 5108 kB
VmRSS: 5108 kB
RssAnon: 92 kB
RssFile: 1324 kB
RssShmem: 3692 kB
VmData: 192 kB
VmStk: 136 kB
VmExe: 4 kB
VmLib: 1784 kB
VmPTE: 3928 kB
VmPMD: 20 kB
VmSwap: 0 kB
HugetlbPages: 0 kB
[vbabka@suse.cz: forward-porting, tweak changelog]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 02:19:29 +03:00
RssAnon: 352 kB
RssFile: 120 kB
RssShmem: 4 kB
2009-06-18 03:26:01 +04:00
VmData: 156 kB
VmStk: 88 kB
VmExe: 68 kB
VmLib: 1412 kB
VmPTE: 20 kb
2010-03-06 00:41:42 +03:00
VmSwap: 0 kB
2015-11-06 05:47:14 +03:00
HugetlbPages: 0 kB
2017-11-18 02:26:45 +03:00
CoreDumping: 0
2018-12-28 11:38:25 +03:00
THP_enabled: 1
2009-06-18 03:26:01 +04:00
Threads: 1
SigQ: 0/28578
SigPnd: 0000000000000000
ShdPnd: 0000000000000000
SigBlk: 0000000000000000
SigIgn: 0000000000000000
SigCgt: 0000000000000000
CapInh: 00000000fffffeff
CapPrm: 0000000000000000
CapEff: 0000000000000000
CapBnd: ffffffffffffffff
2018-10-24 00:25:51 +03:00
CapAmb: 0000000000000000
2016-12-13 03:45:05 +03:00
NoNewPrivs: 0
2012-12-18 04:03:14 +04:00
Seccomp: 0
2018-10-24 00:25:51 +03:00
Speculation_Store_Bypass: thread vulnerable
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voluntary_ctxt_switches: 0
nonvoluntary_ctxt_switches: 1
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This shows you nearly the same information you would get if you viewed it with
the ps command. In fact, ps uses the proc file system to obtain its
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information. But you get a more detailed view of the process by reading the
file /proc/PID/status. It fields are described in table 1-2.
The statm file contains more detailed information about the process
memory usage. Its seven fields are explained in Table 1-3. The stat file
contains details information about the process itself. Its fields are
explained in Table 1-4.
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2010-03-06 00:41:40 +03:00
(for SMP CONFIG users)
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For making accounting scalable, RSS related information are handled in an
asynchronous manner and the value may not be very precise. To see a precise
2010-03-06 00:41:40 +03:00
snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
It's slow but very precise.
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.. table :: Table 1-2: Contents of the status files (as of 4.19)
========================== ===================================================
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Field Content
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========================== ===================================================
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Name filename of the executable
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Umask file mode creation mask
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State state (R is running, S is sleeping, D is sleeping
in an uninterruptible wait, Z is zombie,
T is traced or stopped)
Tgid thread group ID
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Ngid NUMA group ID (0 if none)
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Pid process id
PPid process id of the parent process
TracerPid PID of process tracing this process (0 if not)
Uid Real, effective, saved set, and file system UIDs
Gid Real, effective, saved set, and file system GIDs
FDSize number of file descriptor slots currently allocated
Groups supplementary group list
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NStgid descendant namespace thread group ID hierarchy
NSpid descendant namespace process ID hierarchy
NSpgid descendant namespace process group ID hierarchy
NSsid descendant namespace session ID hierarchy
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VmPeak peak virtual memory size
VmSize total program size
VmLck locked memory size
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VmPin pinned memory size
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VmHWM peak resident set size ("high water mark")
mm, procfs: breakdown RSS for anon, shmem and file in /proc/pid/status
There are several shortcomings with the accounting of shared memory
(SysV shm, shared anonymous mapping, mapping of a tmpfs file). The
values in /proc/<pid>/status and <...>/statm don't allow to distinguish
between shmem memory and a shared mapping to a regular file, even though
theirs implication on memory usage are quite different: during reclaim,
file mapping can be dropped or written back on disk, while shmem needs a
place in swap.
Also, to distinguish the memory occupied by anonymous and file mappings,
one has to read the /proc/pid/statm file, which has a field for the file
mappings (again, including shmem) and total memory occupied by these
mappings (i.e. equivalent to VmRSS in the <...>/status file. Getting
the value for anonymous mappings only is thus not exactly user-friendly
(the statm file is intended to be rather efficiently machine-readable).
To address both of these shortcomings, this patch adds a breakdown of
VmRSS in /proc/<pid>/status via new fields RssAnon, RssFile and
RssShmem, making use of the previous preparatory patch. These fields
tell the user the memory occupied by private anonymous pages, mapped
regular files and shmem, respectively. Other existing fields in /status
and /statm files are left without change. The /statm file can be
extended in the future, if there's a need for that.
Example (part of) /proc/pid/status output including the new Rss* fields:
VmPeak: 2001008 kB
VmSize: 2001004 kB
VmLck: 0 kB
VmPin: 0 kB
VmHWM: 5108 kB
VmRSS: 5108 kB
RssAnon: 92 kB
RssFile: 1324 kB
RssShmem: 3692 kB
VmData: 192 kB
VmStk: 136 kB
VmExe: 4 kB
VmLib: 1784 kB
VmPTE: 3928 kB
VmPMD: 20 kB
VmSwap: 0 kB
HugetlbPages: 0 kB
[vbabka@suse.cz: forward-porting, tweak changelog]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 02:19:29 +03:00
VmRSS size of memory portions. It contains the three
2020-02-17 19:12:18 +03:00
following parts
(VmRSS = RssAnon + RssFile + RssShmem)
mm, procfs: breakdown RSS for anon, shmem and file in /proc/pid/status
There are several shortcomings with the accounting of shared memory
(SysV shm, shared anonymous mapping, mapping of a tmpfs file). The
values in /proc/<pid>/status and <...>/statm don't allow to distinguish
between shmem memory and a shared mapping to a regular file, even though
theirs implication on memory usage are quite different: during reclaim,
file mapping can be dropped or written back on disk, while shmem needs a
place in swap.
Also, to distinguish the memory occupied by anonymous and file mappings,
one has to read the /proc/pid/statm file, which has a field for the file
mappings (again, including shmem) and total memory occupied by these
mappings (i.e. equivalent to VmRSS in the <...>/status file. Getting
the value for anonymous mappings only is thus not exactly user-friendly
(the statm file is intended to be rather efficiently machine-readable).
To address both of these shortcomings, this patch adds a breakdown of
VmRSS in /proc/<pid>/status via new fields RssAnon, RssFile and
RssShmem, making use of the previous preparatory patch. These fields
tell the user the memory occupied by private anonymous pages, mapped
regular files and shmem, respectively. Other existing fields in /status
and /statm files are left without change. The /statm file can be
extended in the future, if there's a need for that.
Example (part of) /proc/pid/status output including the new Rss* fields:
VmPeak: 2001008 kB
VmSize: 2001004 kB
VmLck: 0 kB
VmPin: 0 kB
VmHWM: 5108 kB
VmRSS: 5108 kB
RssAnon: 92 kB
RssFile: 1324 kB
RssShmem: 3692 kB
VmData: 192 kB
VmStk: 136 kB
VmExe: 4 kB
VmLib: 1784 kB
VmPTE: 3928 kB
VmPMD: 20 kB
VmSwap: 0 kB
HugetlbPages: 0 kB
[vbabka@suse.cz: forward-porting, tweak changelog]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 02:19:29 +03:00
RssAnon size of resident anonymous memory
RssFile size of resident file mappings
RssShmem size of resident shmem memory (includes SysV shm,
mapping of tmpfs and shared anonymous mappings)
2016-02-03 03:57:46 +03:00
VmData size of private data segments
VmStk size of stack segments
2009-06-18 03:26:01 +04:00
VmExe size of text segment
VmLib size of shared library code
VmPTE size of page table entries
mm, documentation: clarify /proc/pid/status VmSwap limitations for shmem
This series is based on Jerome Marchand's [1] so let me quote the first
paragraph from there:
There are several shortcomings with the accounting of shared memory
(sysV shm, shared anonymous mapping, mapping to a tmpfs file). The
values in /proc/<pid>/status and statm don't allow to distinguish
between shmem memory and a shared mapping to a regular file, even though
their implications on memory usage are quite different: at reclaim, file
mapping can be dropped or written back on disk while shmem needs a place
in swap. As for shmem pages that are swapped-out or in swap cache, they
aren't accounted at all.
The original motivation for myself is that a customer found (IMHO
rightfully) confusing that e.g. top output for process swap usage is
unreliable with respect to swapped out shmem pages, which are not
accounted for.
The fundamental difference between private anonymous and shmem pages is
that the latter has PTE's converted to pte_none, and not swapents. As
such, they are not accounted to the number of swapents visible e.g. in
/proc/pid/status VmSwap row. It might be theoretically possible to use
swapents when swapping out shmem (without extra cost, as one has to
change all mappers anyway), and on swap in only convert the swapent for
the faulting process, leaving swapents in other processes until they
also fault (so again no extra cost). But I don't know how many
assumptions this would break, and it would be too disruptive change for
a relatively small benefit.
Instead, my approach is to document the limitation of VmSwap, and
provide means to determine the swap usage for shmem areas for those who
are interested and willing to pay the price, using /proc/pid/smaps.
Because outside of ipcs, I don't think it's possible to currently to
determine the usage at all. The previous patchset [1] did introduce new
shmem-specific fields into smaps output, and functions to determine the
values. I take a simpler approach, noting that smaps output already has
a "Swap: X kB" line, where currently X == 0 always for shmem areas. I
think we can just consider this a bug and provide the proper value by
consulting the radix tree, as e.g. mincore_page() does. In the patch
changelog I explain why this is also not perfect (and cannot be without
swapents), but still arguably much better than showing a 0.
The last two patches are adapted from Jerome's patchset and provide a
VmRSS breakdown to RssAnon, RssFile and RssShm in /proc/pid/status.
Hugh noted that this is a welcome addition, and I agree that it might
help e.g. debugging process memory usage at albeit non-zero, but still
rather low cost of extra per-mm counter and some page flag checks.
[1] http://lwn.net/Articles/611966/
This patch (of 6):
The documentation for /proc/pid/status does not mention that the value
of VmSwap counts only swapped out anonymous private pages, and not
swapped out pages of the underlying shmem objects (for shmem mappings).
This is not obvious, so document this limitation.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 02:19:14 +03:00
VmSwap amount of swap used by anonymous private data
(shmem swap usage is not included)
2015-11-06 05:47:14 +03:00
HugetlbPages size of hugetlb memory portions
2017-11-18 02:26:45 +03:00
CoreDumping process's memory is currently being dumped
(killing the process may lead to a corrupted core)
2018-12-28 11:38:25 +03:00
THP_enabled process is allowed to use THP (returns 0 when
PR_SET_THP_DISABLE is set on the process
2009-06-18 03:26:01 +04:00
Threads number of threads
SigQ number of signals queued/max. number for queue
SigPnd bitmap of pending signals for the thread
ShdPnd bitmap of shared pending signals for the process
SigBlk bitmap of blocked signals
SigIgn bitmap of ignored signals
2014-04-05 06:31:00 +04:00
SigCgt bitmap of caught signals
2009-06-18 03:26:01 +04:00
CapInh bitmap of inheritable capabilities
CapPrm bitmap of permitted capabilities
CapEff bitmap of effective capabilities
CapBnd bitmap of capabilities bounding set
2018-10-24 00:25:51 +03:00
CapAmb bitmap of ambient capabilities
2016-12-13 03:45:05 +03:00
NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...)
2012-12-18 04:03:14 +04:00
Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...)
2018-10-24 00:25:51 +03:00
Speculation_Store_Bypass speculative store bypass mitigation status
2009-06-18 03:26:01 +04:00
Cpus_allowed mask of CPUs on which this process may run
Cpus_allowed_list Same as previous, but in "list format"
Mems_allowed mask of memory nodes allowed to this process
Mems_allowed_list Same as previous, but in "list format"
voluntary_ctxt_switches number of voluntary context switches
nonvoluntary_ctxt_switches number of non voluntary context switches
2020-02-17 19:12:18 +03:00
========================== ===================================================
2005-04-17 02:20:36 +04:00
2020-02-17 19:12:18 +03:00
.. table :: Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
======== =============================== ==============================
2005-04-17 02:20:36 +04:00
Field Content
2020-02-17 19:12:18 +03:00
======== =============================== ==============================
2005-04-17 02:20:36 +04:00
size total program size (pages) (same as VmSize in status)
resident size of memory portions (pages) (same as VmRSS in status)
mm, procfs: breakdown RSS for anon, shmem and file in /proc/pid/status
There are several shortcomings with the accounting of shared memory
(SysV shm, shared anonymous mapping, mapping of a tmpfs file). The
values in /proc/<pid>/status and <...>/statm don't allow to distinguish
between shmem memory and a shared mapping to a regular file, even though
theirs implication on memory usage are quite different: during reclaim,
file mapping can be dropped or written back on disk, while shmem needs a
place in swap.
Also, to distinguish the memory occupied by anonymous and file mappings,
one has to read the /proc/pid/statm file, which has a field for the file
mappings (again, including shmem) and total memory occupied by these
mappings (i.e. equivalent to VmRSS in the <...>/status file. Getting
the value for anonymous mappings only is thus not exactly user-friendly
(the statm file is intended to be rather efficiently machine-readable).
To address both of these shortcomings, this patch adds a breakdown of
VmRSS in /proc/<pid>/status via new fields RssAnon, RssFile and
RssShmem, making use of the previous preparatory patch. These fields
tell the user the memory occupied by private anonymous pages, mapped
regular files and shmem, respectively. Other existing fields in /status
and /statm files are left without change. The /statm file can be
extended in the future, if there's a need for that.
Example (part of) /proc/pid/status output including the new Rss* fields:
VmPeak: 2001008 kB
VmSize: 2001004 kB
VmLck: 0 kB
VmPin: 0 kB
VmHWM: 5108 kB
VmRSS: 5108 kB
RssAnon: 92 kB
RssFile: 1324 kB
RssShmem: 3692 kB
VmData: 192 kB
VmStk: 136 kB
VmExe: 4 kB
VmLib: 1784 kB
VmPTE: 3928 kB
VmPMD: 20 kB
VmSwap: 0 kB
HugetlbPages: 0 kB
[vbabka@suse.cz: forward-porting, tweak changelog]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 02:19:29 +03:00
shared number of pages that are shared (i.e. backed by a file, same
as RssFile+RssShmem in status)
2005-04-17 02:20:36 +04:00
trs number of pages that are 'code' (not including libs; broken,
2020-02-17 19:12:18 +03:00
includes data segment)
2005-04-17 02:20:36 +04:00
lrs number of pages of library (always 0 on 2.6)
drs number of pages of data/stack (including libs; broken,
2020-02-17 19:12:18 +03:00
includes library text)
2005-04-17 02:20:36 +04:00
dt number of dirty pages (always 0 on 2.6)
2020-02-17 19:12:18 +03:00
======== =============================== ==============================
2005-04-17 02:20:36 +04:00
2020-02-17 19:12:18 +03:00
.. table :: Table 1-4: Contents of the stat files (as of 2.6.30-rc7)
2007-07-16 10:40:38 +04:00
2020-02-17 19:12:18 +03:00
============= ===============================================================
Field Content
============= ===============================================================
2007-07-16 10:40:38 +04:00
pid process id
tcomm filename of the executable
state state (R is running, S is sleeping, D is sleeping in an
uninterruptible wait, Z is zombie, T is traced or stopped)
ppid process id of the parent process
pgrp pgrp of the process
sid session id
tty_nr tty the process uses
tty_pgrp pgrp of the tty
flags task flags
min_flt number of minor faults
cmin_flt number of minor faults with child's
maj_flt number of major faults
cmaj_flt number of major faults with child's
utime user mode jiffies
stime kernel mode jiffies
cutime user mode jiffies with child's
cstime kernel mode jiffies with child's
priority priority level
nice nice level
num_threads number of threads
2008-02-03 17:17:16 +03:00
it_real_value (obsolete, always 0)
2007-07-16 10:40:38 +04:00
start_time time the process started after system boot
vsize virtual memory size
rss resident set memory size
rsslim current limit in bytes on the rss
start_code address above which program text can run
end_code address below which program text can run
procfs: mark thread stack correctly in proc/<pid>/maps
Stack for a new thread is mapped by userspace code and passed via
sys_clone. This memory is currently seen as anonymous in
/proc/<pid>/maps, which makes it difficult to ascertain which mappings
are being used for thread stacks. This patch uses the individual task
stack pointers to determine which vmas are actually thread stacks.
For a multithreaded program like the following:
#include <pthread.h>
void *thread_main(void *foo)
{
while(1);
}
int main()
{
pthread_t t;
pthread_create(&t, NULL, thread_main, NULL);
pthread_join(t, NULL);
}
proc/PID/maps looks like the following:
00400000-00401000 r-xp 00000000 fd:0a 3671804 /home/siddhesh/a.out
00600000-00601000 rw-p 00000000 fd:0a 3671804 /home/siddhesh/a.out
019ef000-01a10000 rw-p 00000000 00:00 0 [heap]
7f8a44491000-7f8a44492000 ---p 00000000 00:00 0
7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0
7f8a44c92000-7f8a44e3d000 r-xp 00000000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a44e3d000-7f8a4503d000 ---p 001ab000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a4503d000-7f8a45041000 r--p 001ab000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a45041000-7f8a45043000 rw-p 001af000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a45043000-7f8a45048000 rw-p 00000000 00:00 0
7f8a45048000-7f8a4505f000 r-xp 00000000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a4505f000-7f8a4525e000 ---p 00017000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a4525e000-7f8a4525f000 r--p 00016000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a4525f000-7f8a45260000 rw-p 00017000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a45260000-7f8a45264000 rw-p 00000000 00:00 0
7f8a45264000-7f8a45286000 r-xp 00000000 fd:00 2097348 /lib64/ld-2.14.90.so
7f8a45457000-7f8a4545a000 rw-p 00000000 00:00 0
7f8a45484000-7f8a45485000 rw-p 00000000 00:00 0
7f8a45485000-7f8a45486000 r--p 00021000 fd:00 2097348 /lib64/ld-2.14.90.so
7f8a45486000-7f8a45487000 rw-p 00022000 fd:00 2097348 /lib64/ld-2.14.90.so
7f8a45487000-7f8a45488000 rw-p 00000000 00:00 0
7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0 [stack]
7fff627ff000-7fff62800000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
Here, one could guess that 7f8a44492000-7f8a44c92000 is a stack since
the earlier vma that has no permissions (7f8a44e3d000-7f8a4503d000) but
that is not always a reliable way to find out which vma is a thread
stack. Also, /proc/PID/maps and /proc/PID/task/TID/maps has the same
content.
With this patch in place, /proc/PID/task/TID/maps are treated as 'maps
as the task would see it' and hence, only the vma that that task uses as
stack is marked as [stack]. All other 'stack' vmas are marked as
anonymous memory. /proc/PID/maps acts as a thread group level view,
where all thread stack vmas are marked as [stack:TID] where TID is the
process ID of the task that uses that vma as stack, while the process
stack is marked as [stack].
So /proc/PID/maps will look like this:
00400000-00401000 r-xp 00000000 fd:0a 3671804 /home/siddhesh/a.out
00600000-00601000 rw-p 00000000 fd:0a 3671804 /home/siddhesh/a.out
019ef000-01a10000 rw-p 00000000 00:00 0 [heap]
7f8a44491000-7f8a44492000 ---p 00000000 00:00 0
7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0 [stack:1442]
7f8a44c92000-7f8a44e3d000 r-xp 00000000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a44e3d000-7f8a4503d000 ---p 001ab000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a4503d000-7f8a45041000 r--p 001ab000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a45041000-7f8a45043000 rw-p 001af000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a45043000-7f8a45048000 rw-p 00000000 00:00 0
7f8a45048000-7f8a4505f000 r-xp 00000000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a4505f000-7f8a4525e000 ---p 00017000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a4525e000-7f8a4525f000 r--p 00016000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a4525f000-7f8a45260000 rw-p 00017000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a45260000-7f8a45264000 rw-p 00000000 00:00 0
7f8a45264000-7f8a45286000 r-xp 00000000 fd:00 2097348 /lib64/ld-2.14.90.so
7f8a45457000-7f8a4545a000 rw-p 00000000 00:00 0
7f8a45484000-7f8a45485000 rw-p 00000000 00:00 0
7f8a45485000-7f8a45486000 r--p 00021000 fd:00 2097348 /lib64/ld-2.14.90.so
7f8a45486000-7f8a45487000 rw-p 00022000 fd:00 2097348 /lib64/ld-2.14.90.so
7f8a45487000-7f8a45488000 rw-p 00000000 00:00 0
7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0 [stack]
7fff627ff000-7fff62800000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
Thus marking all vmas that are used as stacks by the threads in the
thread group along with the process stack. The task level maps will
however like this:
00400000-00401000 r-xp 00000000 fd:0a 3671804 /home/siddhesh/a.out
00600000-00601000 rw-p 00000000 fd:0a 3671804 /home/siddhesh/a.out
019ef000-01a10000 rw-p 00000000 00:00 0 [heap]
7f8a44491000-7f8a44492000 ---p 00000000 00:00 0
7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0 [stack]
7f8a44c92000-7f8a44e3d000 r-xp 00000000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a44e3d000-7f8a4503d000 ---p 001ab000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a4503d000-7f8a45041000 r--p 001ab000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a45041000-7f8a45043000 rw-p 001af000 fd:00 2097482 /lib64/libc-2.14.90.so
7f8a45043000-7f8a45048000 rw-p 00000000 00:00 0
7f8a45048000-7f8a4505f000 r-xp 00000000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a4505f000-7f8a4525e000 ---p 00017000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a4525e000-7f8a4525f000 r--p 00016000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a4525f000-7f8a45260000 rw-p 00017000 fd:00 2099938 /lib64/libpthread-2.14.90.so
7f8a45260000-7f8a45264000 rw-p 00000000 00:00 0
7f8a45264000-7f8a45286000 r-xp 00000000 fd:00 2097348 /lib64/ld-2.14.90.so
7f8a45457000-7f8a4545a000 rw-p 00000000 00:00 0
7f8a45484000-7f8a45485000 rw-p 00000000 00:00 0
7f8a45485000-7f8a45486000 r--p 00021000 fd:00 2097348 /lib64/ld-2.14.90.so
7f8a45486000-7f8a45487000 rw-p 00022000 fd:00 2097348 /lib64/ld-2.14.90.so
7f8a45487000-7f8a45488000 rw-p 00000000 00:00 0
7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0
7fff627ff000-7fff62800000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
where only the vma that is being used as a stack by *that* task is
marked as [stack].
Analogous changes have been made to /proc/PID/smaps,
/proc/PID/numa_maps, /proc/PID/task/TID/smaps and
/proc/PID/task/TID/numa_maps. Relevant snippets from smaps and
numa_maps:
[siddhesh@localhost ~ ]$ pgrep a.out
1441
[siddhesh@localhost ~ ]$ cat /proc/1441/smaps | grep "\[stack"
7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0 [stack:1442]
7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0 [stack]
[siddhesh@localhost ~ ]$ cat /proc/1441/task/1442/smaps | grep "\[stack"
7f8a44492000-7f8a44c92000 rw-p 00000000 00:00 0 [stack]
[siddhesh@localhost ~ ]$ cat /proc/1441/task/1441/smaps | grep "\[stack"
7fff6273b000-7fff6275c000 rw-p 00000000 00:00 0 [stack]
[siddhesh@localhost ~ ]$ cat /proc/1441/numa_maps | grep "stack"
7f8a44492000 default stack:1442 anon=2 dirty=2 N0=2
7fff6273a000 default stack anon=3 dirty=3 N0=3
[siddhesh@localhost ~ ]$ cat /proc/1441/task/1442/numa_maps | grep "stack"
7f8a44492000 default stack anon=2 dirty=2 N0=2
[siddhesh@localhost ~ ]$ cat /proc/1441/task/1441/numa_maps | grep "stack"
7fff6273a000 default stack anon=3 dirty=3 N0=3
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix build]
Signed-off-by: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jamie Lokier <jamie@shareable.org>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 03:34:04 +04:00
start_stack address of the start of the main process stack
2007-07-16 10:40:38 +04:00
esp current value of ESP
eip current value of EIP
2009-06-18 03:26:01 +04:00
pending bitmap of pending signals
blocked bitmap of blocked signals
sigign bitmap of ignored signals
2014-04-05 06:31:00 +04:00
sigcatch bitmap of caught signals
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0 (place holder, used to be the wchan address,
use /proc/PID/wchan instead)
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0 (place holder)
0 (place holder)
exit_signal signal to send to parent thread on exit
task_cpu which CPU the task is scheduled on
rt_priority realtime priority
policy scheduling policy (man sched_setscheduler)
blkio_ticks time spent waiting for block IO
2009-06-18 03:26:01 +04:00
gtime guest time of the task in jiffies
cgtime guest time of the task children in jiffies
2012-01-13 05:20:53 +04:00
start_data address above which program data+bss is placed
end_data address below which program data+bss is placed
start_brk address above which program heap can be expanded with brk()
2012-06-01 03:26:44 +04:00
arg_start address above which program command line is placed
arg_end address below which program command line is placed
env_start address above which program environment is placed
env_end address below which program environment is placed
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exit_code the thread's exit_code in the form reported by the waitpid
system call
============= ===============================================================
2007-07-16 10:40:38 +04:00
2019-07-12 07:00:10 +03:00
The /proc/PID/maps file contains the currently mapped memory regions and
2009-06-18 03:26:01 +04:00
their access permissions.
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The format is::
address perms offset dev inode pathname
08048000-08049000 r-xp 00000000 03:00 8312 /opt/test
08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
a7cb1000-a7cb2000 ---p 00000000 00:00 0
a7cb2000-a7eb2000 rw-p 00000000 00:00 0
a7eb2000-a7eb3000 ---p 00000000 00:00 0
a7eb3000-a7ed5000 rw-p 00000000 00:00 0
a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
a800b000-a800e000 rw-p 00000000 00:00 0
a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
a8024000-a8027000 rw-p 00000000 00:00 0
a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
2009-06-18 03:26:01 +04:00
where "address" is the address space in the process that it occupies, "perms"
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is a set of permissions::
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r = read
w = write
x = execute
s = shared
p = private (copy on write)
"offset" is the offset into the mapping, "dev" is the device (major:minor), and
"inode" is the inode on that device. 0 indicates that no inode is associated
with the memory region, as the case would be with BSS (uninitialized data).
The "pathname" shows the name associated file for this mapping. If the mapping
is not associated with a file:
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======= ====================================
[heap] the heap of the program
[stack] the stack of the main process
[vdso] the "virtual dynamic shared object",
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the kernel system call handler
2020-02-17 19:12:18 +03:00
======= ====================================
2009-06-18 03:26:01 +04:00
or if empty, the mapping is anonymous.
The /proc/PID/smaps is an extension based on maps, showing the memory
2019-07-12 07:00:10 +03:00
consumption for each of the process's mappings. For each mapping (aka Virtual
2020-02-17 19:12:18 +03:00
Memory Area, or VMA) there is a series of lines such as the following::
08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
Size: 1084 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
Rss: 892 kB
Pss: 374 kB
Shared_Clean: 892 kB
Shared_Dirty: 0 kB
Private_Clean: 0 kB
Private_Dirty: 0 kB
Referenced: 892 kB
Anonymous: 0 kB
LazyFree: 0 kB
AnonHugePages: 0 kB
ShmemPmdMapped: 0 kB
Shared_Hugetlb: 0 kB
Private_Hugetlb: 0 kB
Swap: 0 kB
SwapPss: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
Locked: 0 kB
THPeligible: 0
VmFlags: rd ex mr mw me dw
2009-06-18 03:26:01 +04:00
2019-07-12 07:00:10 +03:00
The first of these lines shows the same information as is displayed for the
mapping in /proc/PID/maps. Following lines show the size of the mapping
(size); the size of each page allocated when backing a VMA (KernelPageSize),
which is usually the same as the size in the page table entries; the page size
used by the MMU when backing a VMA (in most cases, the same as KernelPageSize);
the amount of the mapping that is currently resident in RAM (RSS); the
process' proportional share of this mapping (PSS); and the number of clean and
dirty shared and private pages in the mapping.
2015-09-09 01:00:24 +03:00
The "proportional set size" (PSS) of a process is the count of pages it has
in memory, where each page is divided by the number of processes sharing it.
So if a process has 1000 pages all to itself, and 1000 shared with one other
process, its PSS will be 1500.
2020-02-17 19:12:18 +03:00
2015-09-09 01:00:24 +03:00
Note that even a page which is part of a MAP_SHARED mapping, but has only
a single pte mapped, i.e. is currently used by only one process, is accounted
as private and not as shared.
2020-02-17 19:12:18 +03:00
2015-09-09 01:00:24 +03:00
"Referenced" indicates the amount of memory currently marked as referenced or
accessed.
2020-02-17 19:12:18 +03:00
2010-10-28 02:34:10 +04:00
"Anonymous" shows the amount of memory that does not belong to any file. Even
a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
and a page is modified, the file page is replaced by a private anonymous copy.
2020-02-17 19:12:18 +03:00
2017-05-04 00:52:42 +03:00
"LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE).
The memory isn't freed immediately with madvise(). It's freed in memory
pressure if the memory is clean. Please note that the printed value might
be lower than the real value due to optimizations used in the current
implementation. If this is not desirable please file a bug report.
2020-02-17 19:12:18 +03:00
2015-11-06 05:47:11 +03:00
"AnonHugePages" shows the ammount of memory backed by transparent hugepage.
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2016-07-27 01:26:40 +03:00
"ShmemPmdMapped" shows the ammount of shared (shmem/tmpfs) memory backed by
huge pages.
2020-02-17 19:12:18 +03:00
2015-11-06 05:47:11 +03:00
"Shared_Hugetlb" and "Private_Hugetlb" show the ammounts of memory backed by
hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical
reasons. And these are not included in {Shared,Private}_{Clean,Dirty} field.
2020-02-17 19:12:18 +03:00
2015-11-06 05:50:37 +03:00
"Swap" shows how much would-be-anonymous memory is also used, but out on swap.
2020-02-17 19:12:18 +03:00
mm, proc: account for shmem swap in /proc/pid/smaps
Currently, /proc/pid/smaps will always show "Swap: 0 kB" for
shmem-backed mappings, even if the mapped portion does contain pages
that were swapped out. This is because unlike private anonymous
mappings, shmem does not change pte to swap entry, but pte_none when
swapping the page out. In the smaps page walk, such page thus looks
like it was never faulted in.
This patch changes smaps_pte_entry() to determine the swap status for
such pte_none entries for shmem mappings, similarly to how
mincore_page() does it. Swapped out shmem pages are thus accounted for.
For private mappings of tmpfs files that COWed some of the pages, swaped
out status of the original shmem pages is naturally ignored. If some of
the private copies was also swapped out, they are accounted via their
page table swap entries, so the resulting reported swap usage is then a
sum of both swapped out private copies, and swapped out shmem pages that
were not COWed. No double accounting can thus happen.
The accounting is arguably still not as precise as for private anonymous
mappings, since now we will count also pages that the process in
question never accessed, but another process populated them and then let
them become swapped out. I believe it is still less confusing and
subtle than not showing any swap usage by shmem mappings at all.
Swapped out counter might of interest of users who would like to prevent
from future swapins during performance critical operation and pre-fault
them at their convenience. Especially for larger swapped out regions
the cost of swapin is much higher than a fresh page allocation. So a
differentiation between pte_none vs. swapped out is important for those
usecases.
One downside of this patch is that it makes /proc/pid/smaps more
expensive for shmem mappings, as we consult the radix tree for each
pte_none entry, so the overal complexity is O(n*log(n)). I have
measured this on a process that creates a 2GB mapping and dirties single
pages with a stride of 2MB, and time how long does it take to cat
/proc/pid/smaps of this process 100 times.
Private anonymous mapping:
real 0m0.949s
user 0m0.116s
sys 0m0.348s
Mapping of a /dev/shm/file:
real 0m3.831s
user 0m0.180s
sys 0m3.212s
The difference is rather substantial, so the next patch will reduce the
cost for shared or read-only mappings.
In a less controlled experiment, I've gathered pids of processes on my
desktop that have either '/dev/shm/*' or 'SYSV*' in smaps. This
included the Chrome browser and some KDE processes. Again, I've run cat
/proc/pid/smaps on each 100 times.
Before this patch:
real 0m9.050s
user 0m0.518s
sys 0m8.066s
After this patch:
real 0m9.221s
user 0m0.541s
sys 0m8.187s
This suggests low impact on average systems.
Note that this patch doesn't attempt to adjust the SwapPss field for
shmem mappings, which would need extra work to determine who else could
have the pages mapped. Thus the value stays zero except for COWed
swapped out pages in a shmem mapping, which are accounted as usual.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 02:19:17 +03:00
For shmem mappings, "Swap" includes also the size of the mapped (and not
replaced by copy-on-write) part of the underlying shmem object out on swap.
"SwapPss" shows proportional swap share of this mapping. Unlike "Swap", this
does not take into account swapped out page of underlying shmem objects.
2015-11-06 05:50:37 +03:00
"Locked" indicates whether the mapping is locked in memory or not.
mm: thp: fix false negative of shmem vma's THP eligibility
Commit 7635d9cbe832 ("mm, thp, proc: report THP eligibility for each
vma") introduced THPeligible bit for processes' smaps. But, when
checking the eligibility for shmem vma, __transparent_hugepage_enabled()
is called to override the result from shmem_huge_enabled(). It may
result in the anonymous vma's THP flag override shmem's. For example,
running a simple test which create THP for shmem, but with anonymous THP
disabled, when reading the process's smaps, it may show:
7fc92ec00000-7fc92f000000 rw-s 00000000 00:14 27764 /dev/shm/test
Size: 4096 kB
...
[snip]
...
ShmemPmdMapped: 4096 kB
...
[snip]
...
THPeligible: 0
And, /proc/meminfo does show THP allocated and PMD mapped too:
ShmemHugePages: 4096 kB
ShmemPmdMapped: 4096 kB
This doesn't make too much sense. The shmem objects should be treated
separately from anonymous THP. Calling shmem_huge_enabled() with
checking MMF_DISABLE_THP sounds good enough. And, we could skip stack
and dax vma check since we already checked if the vma is shmem already.
Also check if vma is suitable for THP by calling
transhuge_vma_suitable().
And minor fix to smaps output format and documentation.
Link: http://lkml.kernel.org/r/1560401041-32207-3-git-send-email-yang.shi@linux.alibaba.com
Fixes: 7635d9cbe832 ("mm, thp, proc: report THP eligibility for each vma")
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-19 01:57:27 +03:00
"THPeligible" indicates whether the mapping is eligible for allocating THP
pages - 1 if true, 0 otherwise. It just shows the current status.
2015-11-06 05:47:11 +03:00
2020-02-17 19:12:18 +03:00
"VmFlags" field deserves a separate description. This member represents the
kernel flags associated with the particular virtual memory area in two letter
encoded manner. The codes are the following:
== =======================================
rd readable
wr writeable
ex executable
sh shared
mr may read
mw may write
me may execute
ms may share
gd stack segment growns down
pf pure PFN range
dw disabled write to the mapped file
lo pages are locked in memory
io memory mapped I/O area
sr sequential read advise provided
rr random read advise provided
dc do not copy area on fork
de do not expand area on remapping
ac area is accountable
nr swap space is not reserved for the area
ht area uses huge tlb pages
ar architecture specific flag
dd do not include area into core dump
sd soft dirty flag
mm mixed map area
hg huge page advise flag
nh no huge page advise flag
mg mergable advise flag
== =======================================
2012-12-18 04:03:13 +04:00
Note that there is no guarantee that every flag and associated mnemonic will
be present in all further kernel releases. Things get changed, the flags may
2018-12-28 11:38:17 +03:00
be vanished or the reverse -- new added. Interpretation of their meaning
might change in future as well. So each consumer of these flags has to
follow each specific kernel version for the exact semantic.
2012-12-18 04:03:13 +04:00
2009-06-18 03:26:01 +04:00
This file is only present if the CONFIG_MMU kernel configuration option is
enabled.
2007-07-16 10:40:38 +04:00
2016-10-08 03:02:39 +03:00
Note: reading /proc/PID/maps or /proc/PID/smaps is inherently racy (consistent
output can be achieved only in the single read call).
2020-02-17 19:12:18 +03:00
2016-10-08 03:02:39 +03:00
This typically manifests when doing partial reads of these files while the
memory map is being modified. Despite the races, we do provide the following
guarantees:
1) The mapped addresses never go backwards, which implies no two
regions will ever overlap.
2) If there is something at a given vaddr during the entirety of the
life of the smaps/maps walk, there will be some output for it.
2019-07-12 07:00:10 +03:00
The /proc/PID/smaps_rollup file includes the same fields as /proc/PID/smaps,
but their values are the sums of the corresponding values for all mappings of
the process. Additionally, it contains these fields:
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- Pss_Anon
- Pss_File
- Pss_Shmem
2019-07-12 07:00:10 +03:00
They represent the proportional shares of anonymous, file, and shmem pages, as
described for smaps above. These fields are omitted in smaps since each
mapping identifies the type (anon, file, or shmem) of all pages it contains.
Thus all information in smaps_rollup can be derived from smaps, but at a
significantly higher cost.
2016-10-08 03:02:39 +03:00
2009-09-22 04:02:29 +04:00
The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
mm: soft-dirty bits for user memory changes tracking
The soft-dirty is a bit on a PTE which helps to track which pages a task
writes to. In order to do this tracking one should
1. Clear soft-dirty bits from PTEs ("echo 4 > /proc/PID/clear_refs)
2. Wait some time.
3. Read soft-dirty bits (55'th in /proc/PID/pagemap2 entries)
To do this tracking, the writable bit is cleared from PTEs when the
soft-dirty bit is. Thus, after this, when the task tries to modify a
page at some virtual address the #PF occurs and the kernel sets the
soft-dirty bit on the respective PTE.
Note, that although all the task's address space is marked as r/o after
the soft-dirty bits clear, the #PF-s that occur after that are processed
fast. This is so, since the pages are still mapped to physical memory,
and thus all the kernel does is finds this fact out and puts back
writable, dirty and soft-dirty bits on the PTE.
Another thing to note, is that when mremap moves PTEs they are marked
with soft-dirty as well, since from the user perspective mremap modifies
the virtual memory at mremap's new address.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-04 02:01:20 +04:00
bits on both physical and virtual pages associated with a process, and the
2018-04-18 11:07:49 +03:00
soft-dirty bit on pte (see Documentation/admin-guide/mm/soft-dirty.rst
for details).
2020-02-17 19:12:18 +03:00
To clear the bits for all the pages associated with the process::
2009-09-22 04:02:29 +04:00
> echo 1 > /proc/PID/clear_refs
2020-02-17 19:12:18 +03:00
To clear the bits for the anonymous pages associated with the process::
2009-09-22 04:02:29 +04:00
> echo 2 > /proc/PID/clear_refs
2020-02-17 19:12:18 +03:00
To clear the bits for the file mapped pages associated with the process::
2009-09-22 04:02:29 +04:00
> echo 3 > /proc/PID/clear_refs
mm: soft-dirty bits for user memory changes tracking
The soft-dirty is a bit on a PTE which helps to track which pages a task
writes to. In order to do this tracking one should
1. Clear soft-dirty bits from PTEs ("echo 4 > /proc/PID/clear_refs)
2. Wait some time.
3. Read soft-dirty bits (55'th in /proc/PID/pagemap2 entries)
To do this tracking, the writable bit is cleared from PTEs when the
soft-dirty bit is. Thus, after this, when the task tries to modify a
page at some virtual address the #PF occurs and the kernel sets the
soft-dirty bit on the respective PTE.
Note, that although all the task's address space is marked as r/o after
the soft-dirty bits clear, the #PF-s that occur after that are processed
fast. This is so, since the pages are still mapped to physical memory,
and thus all the kernel does is finds this fact out and puts back
writable, dirty and soft-dirty bits on the PTE.
Another thing to note, is that when mremap moves PTEs they are marked
with soft-dirty as well, since from the user perspective mremap modifies
the virtual memory at mremap's new address.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-04 02:01:20 +04:00
2020-02-17 19:12:18 +03:00
To clear the soft-dirty bit::
mm: soft-dirty bits for user memory changes tracking
The soft-dirty is a bit on a PTE which helps to track which pages a task
writes to. In order to do this tracking one should
1. Clear soft-dirty bits from PTEs ("echo 4 > /proc/PID/clear_refs)
2. Wait some time.
3. Read soft-dirty bits (55'th in /proc/PID/pagemap2 entries)
To do this tracking, the writable bit is cleared from PTEs when the
soft-dirty bit is. Thus, after this, when the task tries to modify a
page at some virtual address the #PF occurs and the kernel sets the
soft-dirty bit on the respective PTE.
Note, that although all the task's address space is marked as r/o after
the soft-dirty bits clear, the #PF-s that occur after that are processed
fast. This is so, since the pages are still mapped to physical memory,
and thus all the kernel does is finds this fact out and puts back
writable, dirty and soft-dirty bits on the PTE.
Another thing to note, is that when mremap moves PTEs they are marked
with soft-dirty as well, since from the user perspective mremap modifies
the virtual memory at mremap's new address.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-04 02:01:20 +04:00
> echo 4 > /proc/PID/clear_refs
2015-02-13 02:01:00 +03:00
To reset the peak resident set size ("high water mark") to the process's
2020-02-17 19:12:18 +03:00
current value::
2015-02-13 02:01:00 +03:00
> echo 5 > /proc/PID/clear_refs
2009-09-22 04:02:29 +04:00
Any other value written to /proc/PID/clear_refs will have no effect.
2010-10-28 02:34:11 +04:00
The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
using /proc/kpageflags and number of times a page is mapped using
2018-04-18 11:07:49 +03:00
/proc/kpagecount. For detailed explanation, see
Documentation/admin-guide/mm/pagemap.rst.
2009-09-22 04:02:29 +04:00
2015-02-13 02:01:05 +03:00
The /proc/pid/numa_maps is an extension based on maps, showing the memory
locality and binding policy, as well as the memory usage (in pages) of
each mapping. The output follows a general format where mapping details get
2020-02-17 19:12:18 +03:00
summarized separated by blank spaces, one mapping per each file line::
address policy mapping details
00400000 default file=/usr/local/bin/app mapped=1 active=0 N3=1 kernelpagesize_kB=4
00600000 default file=/usr/local/bin/app anon=1 dirty=1 N3=1 kernelpagesize_kB=4
3206000000 default file=/lib64/ld-2.12.so mapped=26 mapmax=6 N0=24 N3=2 kernelpagesize_kB=4
320621f000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
3206220000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
3206221000 default anon=1 dirty=1 N3=1 kernelpagesize_kB=4
3206800000 default file=/lib64/libc-2.12.so mapped=59 mapmax=21 active=55 N0=41 N3=18 kernelpagesize_kB=4
320698b000 default file=/lib64/libc-2.12.so
3206b8a000 default file=/lib64/libc-2.12.so anon=2 dirty=2 N3=2 kernelpagesize_kB=4
3206b8e000 default file=/lib64/libc-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
3206b8f000 default anon=3 dirty=3 active=1 N3=3 kernelpagesize_kB=4
7f4dc10a2000 default anon=3 dirty=3 N3=3 kernelpagesize_kB=4
7f4dc10b4000 default anon=2 dirty=2 active=1 N3=2 kernelpagesize_kB=4
7f4dc1200000 default file=/anon_hugepage\040(deleted) huge anon=1 dirty=1 N3=1 kernelpagesize_kB=2048
7fff335f0000 default stack anon=3 dirty=3 N3=3 kernelpagesize_kB=4
7fff3369d000 default mapped=1 mapmax=35 active=0 N3=1 kernelpagesize_kB=4
2015-02-13 02:01:05 +03:00
Where:
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2015-02-13 02:01:05 +03:00
"address" is the starting address for the mapping;
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2018-05-08 10:02:10 +03:00
"policy" reports the NUMA memory policy set for the mapping (see Documentation/admin-guide/mm/numa_memory_policy.rst);
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2015-02-13 02:01:05 +03:00
"mapping details" summarizes mapping data such as mapping type, page usage counters,
node locality page counters (N0 == node0, N1 == node1, ...) and the kernel page
size, in KB, that is backing the mapping up.
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1.2 Kernel data
---------------
Similar to the process entries, the kernel data files give information about
the running kernel. The files used to obtain this information are contained in
2009-06-18 03:26:01 +04:00
/proc and are listed in Table 1-5. Not all of these will be present in your
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system. It depends on the kernel configuration and the loaded modules, which
files are there, and which are missing.
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.. table :: Table 1-5: Kernel info in /proc
============ ===============================================================
File Content
============ ===============================================================
apm Advanced power management info
buddyinfo Kernel memory allocator information (see text) (2.5)
bus Directory containing bus specific information
cmdline Kernel command line
cpuinfo Info about the CPU
devices Available devices (block and character)
dma Used DMS channels
filesystems Supported filesystems
driver Various drivers grouped here, currently rtc (2.4)
execdomains Execdomains, related to security (2.4)
fb Frame Buffer devices (2.4)
fs File system parameters, currently nfs/exports (2.4)
ide Directory containing info about the IDE subsystem
interrupts Interrupt usage
iomem Memory map (2.4)
ioports I/O port usage
irq Masks for irq to cpu affinity (2.4)(smp?)
isapnp ISA PnP (Plug&Play) Info (2.4)
kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
kmsg Kernel messages
ksyms Kernel symbol table
loadavg Load average of last 1, 5 & 15 minutes
locks Kernel locks
meminfo Memory info
misc Miscellaneous
modules List of loaded modules
mounts Mounted filesystems
net Networking info (see text)
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pagetypeinfo Additional page allocator information (see text) (2.5)
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partitions Table of partitions known to the system
pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
decoupled by lspci (2.4)
rtc Real time clock
scsi SCSI info (see text)
slabinfo Slab pool info
softirqs softirq usage
stat Overall statistics
swaps Swap space utilization
sys See chapter 2
sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
tty Info of tty drivers
uptime Wall clock since boot, combined idle time of all cpus
version Kernel version
video bttv info of video resources (2.4)
vmallocinfo Show vmalloced areas
============ ===============================================================
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You can, for example, check which interrupts are currently in use and what
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they are used for by looking in the file /proc/interrupts::
> cat /proc/interrupts
CPU0
0: 8728810 XT-PIC timer
1: 895 XT-PIC keyboard
2: 0 XT-PIC cascade
3: 531695 XT-PIC aha152x
4: 2014133 XT-PIC serial
5: 44401 XT-PIC pcnet_cs
8: 2 XT-PIC rtc
11: 8 XT-PIC i82365
12: 182918 XT-PIC PS/2 Mouse
13: 1 XT-PIC fpu
14: 1232265 XT-PIC ide0
15: 7 XT-PIC ide1
NMI: 0
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In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
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output of a SMP machine)::
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> cat /proc/interrupts
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CPU0 CPU1
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0: 1243498 1214548 IO-APIC-edge timer
1: 8949 8958 IO-APIC-edge keyboard
2: 0 0 XT-PIC cascade
5: 11286 10161 IO-APIC-edge soundblaster
8: 1 0 IO-APIC-edge rtc
9: 27422 27407 IO-APIC-edge 3c503
12: 113645 113873 IO-APIC-edge PS/2 Mouse
13: 0 0 XT-PIC fpu
14: 22491 24012 IO-APIC-edge ide0
15: 2183 2415 IO-APIC-edge ide1
17: 30564 30414 IO-APIC-level eth0
18: 177 164 IO-APIC-level bttv
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NMI: 2457961 2457959
LOC: 2457882 2457881
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ERR: 2155
NMI is incremented in this case because every timer interrupt generates a NMI
(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
LOC is the local interrupt counter of the internal APIC of every CPU.
ERR is incremented in the case of errors in the IO-APIC bus (the bus that
connects the CPUs in a SMP system. This means that an error has been detected,
the IO-APIC automatically retry the transmission, so it should not be a big
problem, but you should read the SMP-FAQ.
2007-10-17 20:04:40 +04:00
In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
/proc/interrupts to display every IRQ vector in use by the system, not
just those considered 'most important'. The new vectors are:
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THR
interrupt raised when a machine check threshold counter
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(typically counting ECC corrected errors of memory or cache) exceeds
a configurable threshold. Only available on some systems.
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TRM
a thermal event interrupt occurs when a temperature threshold
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has been exceeded for the CPU. This interrupt may also be generated
when the temperature drops back to normal.
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SPU
a spurious interrupt is some interrupt that was raised then lowered
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by some IO device before it could be fully processed by the APIC. Hence
the APIC sees the interrupt but does not know what device it came from.
For this case the APIC will generate the interrupt with a IRQ vector
of 0xff. This might also be generated by chipset bugs.
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RES, CAL, TLB]
rescheduling, call and TLB flush interrupts are
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sent from one CPU to another per the needs of the OS. Typically,
their statistics are used by kernel developers and interested users to
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determine the occurrence of interrupts of the given type.
2007-10-17 20:04:40 +04:00
2011-03-31 05:57:33 +04:00
The above IRQ vectors are displayed only when relevant. For example,
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the threshold vector does not exist on x86_64 platforms. Others are
suppressed when the system is a uniprocessor. As of this writing, only
i386 and x86_64 platforms support the new IRQ vector displays.
Of some interest is the introduction of the /proc/irq directory to 2.4.
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It could be used to set IRQ to CPU affinity, this means that you can "hook" an
IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
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irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
prof_cpu_mask.
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For example::
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> ls /proc/irq/
0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
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1 11 13 15 17 19 3 5 7 9 default_smp_affinity
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> ls /proc/irq/0/
smp_affinity
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smp_affinity is a bitmask, in which you can specify which CPUs can handle the
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IRQ, you can set it by doing::
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> echo 1 > /proc/irq/10/smp_affinity
This means that only the first CPU will handle the IRQ, but you can also echo
2016-06-17 16:05:15 +03:00
5 which means that only the first and third CPU can handle the IRQ.
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The contents of each smp_affinity file is the same by default::
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> cat /proc/irq/0/smp_affinity
ffffffff
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bitmap, irq: add smp_affinity_list interface to /proc/irq
Manually adjusting the smp_affinity for IRQ's becomes unwieldy when the
cpu count is large.
Setting smp affinity to cpus 256 to 263 would be:
echo 000000ff,00000000,00000000,00000000,00000000,00000000,00000000,00000000 > smp_affinity
instead of:
echo 256-263 > smp_affinity_list
Think about what it looks like for cpus around say, 4088 to 4095.
We already have many alternate "list" interfaces:
/sys/devices/system/cpu/cpuX/indexY/shared_cpu_list
/sys/devices/system/cpu/cpuX/topology/thread_siblings_list
/sys/devices/system/cpu/cpuX/topology/core_siblings_list
/sys/devices/system/node/nodeX/cpulist
/sys/devices/pci***/***/local_cpulist
Add a companion interface, smp_affinity_list to use cpu lists instead of
cpu maps. This conforms to other companion interfaces where both a map
and a list interface exists.
This required adding a bitmap_parselist_user() function in a manner
similar to the bitmap_parse_user() function.
[akpm@linux-foundation.org: make __bitmap_parselist() static]
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25 04:13:12 +04:00
There is an alternate interface, smp_affinity_list which allows specifying
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a cpu range instead of a bitmask::
bitmap, irq: add smp_affinity_list interface to /proc/irq
Manually adjusting the smp_affinity for IRQ's becomes unwieldy when the
cpu count is large.
Setting smp affinity to cpus 256 to 263 would be:
echo 000000ff,00000000,00000000,00000000,00000000,00000000,00000000,00000000 > smp_affinity
instead of:
echo 256-263 > smp_affinity_list
Think about what it looks like for cpus around say, 4088 to 4095.
We already have many alternate "list" interfaces:
/sys/devices/system/cpu/cpuX/indexY/shared_cpu_list
/sys/devices/system/cpu/cpuX/topology/thread_siblings_list
/sys/devices/system/cpu/cpuX/topology/core_siblings_list
/sys/devices/system/node/nodeX/cpulist
/sys/devices/pci***/***/local_cpulist
Add a companion interface, smp_affinity_list to use cpu lists instead of
cpu maps. This conforms to other companion interfaces where both a map
and a list interface exists.
This required adding a bitmap_parselist_user() function in a manner
similar to the bitmap_parse_user() function.
[akpm@linux-foundation.org: make __bitmap_parselist() static]
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25 04:13:12 +04:00
> cat /proc/irq/0/smp_affinity_list
1024-1031
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The default_smp_affinity mask applies to all non-active IRQs, which are the
IRQs which have not yet been allocated/activated, and hence which lack a
/proc/irq/[0-9]* directory.
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2010-03-12 01:08:56 +03:00
The node file on an SMP system shows the node to which the device using the IRQ
reports itself as being attached. This hardware locality information does not
include information about any possible driver locality preference.
2008-05-29 22:02:52 +04:00
prof_cpu_mask specifies which CPUs are to be profiled by the system wide
bitmap, irq: add smp_affinity_list interface to /proc/irq
Manually adjusting the smp_affinity for IRQ's becomes unwieldy when the
cpu count is large.
Setting smp affinity to cpus 256 to 263 would be:
echo 000000ff,00000000,00000000,00000000,00000000,00000000,00000000,00000000 > smp_affinity
instead of:
echo 256-263 > smp_affinity_list
Think about what it looks like for cpus around say, 4088 to 4095.
We already have many alternate "list" interfaces:
/sys/devices/system/cpu/cpuX/indexY/shared_cpu_list
/sys/devices/system/cpu/cpuX/topology/thread_siblings_list
/sys/devices/system/cpu/cpuX/topology/core_siblings_list
/sys/devices/system/node/nodeX/cpulist
/sys/devices/pci***/***/local_cpulist
Add a companion interface, smp_affinity_list to use cpu lists instead of
cpu maps. This conforms to other companion interfaces where both a map
and a list interface exists.
This required adding a bitmap_parselist_user() function in a manner
similar to the bitmap_parse_user() function.
[akpm@linux-foundation.org: make __bitmap_parselist() static]
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25 04:13:12 +04:00
profiler. Default value is ffffffff (all cpus if there are only 32 of them).
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The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
between all the CPUs which are allowed to handle it. As usual the kernel has
more info than you and does a better job than you, so the defaults are the
bitmap, irq: add smp_affinity_list interface to /proc/irq
Manually adjusting the smp_affinity for IRQ's becomes unwieldy when the
cpu count is large.
Setting smp affinity to cpus 256 to 263 would be:
echo 000000ff,00000000,00000000,00000000,00000000,00000000,00000000,00000000 > smp_affinity
instead of:
echo 256-263 > smp_affinity_list
Think about what it looks like for cpus around say, 4088 to 4095.
We already have many alternate "list" interfaces:
/sys/devices/system/cpu/cpuX/indexY/shared_cpu_list
/sys/devices/system/cpu/cpuX/topology/thread_siblings_list
/sys/devices/system/cpu/cpuX/topology/core_siblings_list
/sys/devices/system/node/nodeX/cpulist
/sys/devices/pci***/***/local_cpulist
Add a companion interface, smp_affinity_list to use cpu lists instead of
cpu maps. This conforms to other companion interfaces where both a map
and a list interface exists.
This required adding a bitmap_parselist_user() function in a manner
similar to the bitmap_parse_user() function.
[akpm@linux-foundation.org: make __bitmap_parselist() static]
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25 04:13:12 +04:00
best choice for almost everyone. [Note this applies only to those IO-APIC's
that support "Round Robin" interrupt distribution.]
2005-04-17 02:20:36 +04:00
There are three more important subdirectories in /proc: net, scsi, and sys.
The general rule is that the contents, or even the existence of these
directories, depend on your kernel configuration. If SCSI is not enabled, the
directory scsi may not exist. The same is true with the net, which is there
only when networking support is present in the running kernel.
The slabinfo file gives information about memory usage at the slab level.
Linux uses slab pools for memory management above page level in version 2.2.
Commonly used objects have their own slab pool (such as network buffers,
directory cache, and so on).
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::
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2020-02-17 19:12:18 +03:00
> cat /proc/buddyinfo
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Node 0, zone DMA 0 4 5 4 4 3 ...
Node 0, zone Normal 1 0 0 1 101 8 ...
Node 0, zone HighMem 2 0 0 1 1 0 ...
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2010-03-06 00:42:15 +03:00
External fragmentation is a problem under some workloads, and buddyinfo is a
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useful tool for helping diagnose these problems. Buddyinfo will give you a
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clue as to how big an area you can safely allocate, or why a previous
allocation failed.
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Each column represents the number of pages of a certain order which are
available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4* PAGE_SIZE
available in ZONE_NORMAL, etc...
2005-04-17 02:20:36 +04:00
2010-03-06 00:42:15 +03:00
More information relevant to external fragmentation can be found in
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pagetypeinfo::
> cat /proc/pagetypeinfo
Page block order: 9
Pages per block: 512
Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
Node 0, zone DMA 2 0 5 1 0
Node 0, zone DMA32 41 6 967 2 0
2010-03-06 00:42:15 +03:00
Fragmentation avoidance in the kernel works by grouping pages of different
migrate types into the same contiguous regions of memory called page blocks.
A page block is typically the size of the default hugepage size e.g. 2MB on
X86-64. By keeping pages grouped based on their ability to move, the kernel
can reclaim pages within a page block to satisfy a high-order allocation.
The pagetypinfo begins with information on the size of a page block. It
then gives the same type of information as buddyinfo except broken down
by migrate-type and finishes with details on how many page blocks of each
type exist.
If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
2016-01-13 10:47:56 +03:00
from libhugetlbfs https://github.com/libhugetlbfs/libhugetlbfs/), one can
2010-03-06 00:42:15 +03:00
make an estimate of the likely number of huge pages that can be allocated
at a given point in time. All the "Movable" blocks should be allocatable
unless memory has been mlock()'d. Some of the Reclaimable blocks should
also be allocatable although a lot of filesystem metadata may have to be
reclaimed to achieve this.
2005-04-17 02:20:36 +04:00
2020-02-17 19:12:18 +03:00
meminfo
~~~~~~~
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Provides information about distribution and utilization of memory. This
varies by architecture and compile options. The following is from a
16GB PIII, which has highmem enabled. You may not have all of these fields.
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::
> cat /proc/meminfo
MemTotal: 16344972 kB
MemFree: 13634064 kB
MemAvailable: 14836172 kB
Buffers: 3656 kB
Cached: 1195708 kB
SwapCached: 0 kB
Active: 891636 kB
Inactive: 1077224 kB
HighTotal: 15597528 kB
HighFree: 13629632 kB
LowTotal: 747444 kB
LowFree: 4432 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 968 kB
Writeback: 0 kB
AnonPages: 861800 kB
Mapped: 280372 kB
Shmem: 644 kB
KReclaimable: 168048 kB
Slab: 284364 kB
SReclaimable: 159856 kB
SUnreclaim: 124508 kB
PageTables: 24448 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 7669796 kB
Committed_AS: 100056 kB
VmallocTotal: 112216 kB
VmallocUsed: 428 kB
VmallocChunk: 111088 kB
Percpu: 62080 kB
HardwareCorrupted: 0 kB
AnonHugePages: 49152 kB
ShmemHugePages: 0 kB
ShmemPmdMapped: 0 kB
MemTotal
Total usable ram (i.e. physical ram minus a few reserved
2005-04-17 02:20:36 +04:00
bits and the kernel binary code)
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MemFree
The sum of LowFree+HighFree
MemAvailable
An estimate of how much memory is available for starting new
/proc/meminfo: provide estimated available memory
Many load balancing and workload placing programs check /proc/meminfo to
estimate how much free memory is available. They generally do this by
adding up "free" and "cached", which was fine ten years ago, but is
pretty much guaranteed to be wrong today.
It is wrong because Cached includes memory that is not freeable as page
cache, for example shared memory segments, tmpfs, and ramfs, and it does
not include reclaimable slab memory, which can take up a large fraction
of system memory on mostly idle systems with lots of files.
Currently, the amount of memory that is available for a new workload,
without pushing the system into swap, can be estimated from MemFree,
Active(file), Inactive(file), and SReclaimable, as well as the "low"
watermarks from /proc/zoneinfo.
However, this may change in the future, and user space really should not
be expected to know kernel internals to come up with an estimate for the
amount of free memory.
It is more convenient to provide such an estimate in /proc/meminfo. If
things change in the future, we only have to change it in one place.
Signed-off-by: Rik van Riel <riel@redhat.com>
Reported-by: Erik Mouw <erik.mouw_2@nxp.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-22 03:49:05 +04:00
applications, without swapping. Calculated from MemFree,
SReclaimable, the size of the file LRU lists, and the low
watermarks in each zone.
The estimate takes into account that the system needs some
page cache to function well, and that not all reclaimable
slab will be reclaimable, due to items being in use. The
impact of those factors will vary from system to system.
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Buffers
Relatively temporary storage for raw disk blocks
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shouldn't get tremendously large (20MB or so)
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Cached
in-memory cache for files read from the disk (the
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pagecache). Doesn't include SwapCached
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SwapCached
Memory that once was swapped out, is swapped back in but
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still also is in the swapfile (if memory is needed it
doesn't need to be swapped out AGAIN because it is already
in the swapfile. This saves I/O)
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Active
Memory that has been used more recently and usually not
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reclaimed unless absolutely necessary.
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Inactive
Memory which has been less recently used. It is more
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eligible to be reclaimed for other purposes
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HighTotal, HighFree
Highmem is all memory above ~860MB of physical memory
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Highmem areas are for use by userspace programs, or
for the pagecache. The kernel must use tricks to access
this memory, making it slower to access than lowmem.
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LowTotal, LowFree
Lowmem is memory which can be used for everything that
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highmem can be used for, but it is also available for the
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kernel's use for its own data structures. Among many
other things, it is where everything from the Slab is
allocated. Bad things happen when you're out of lowmem.
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SwapTotal
total amount of swap space available
SwapFree
Memory which has been evicted from RAM, and is temporarily
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on the disk
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Dirty
Memory which is waiting to get written back to the disk
Writeback
Memory which is actively being written back to the disk
AnonPages
Non-file backed pages mapped into userspace page tables
HardwareCorrupted
The amount of RAM/memory in KB, the kernel identifies as
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corrupted.
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AnonHugePages
Non-file backed huge pages mapped into userspace page tables
Mapped
files which have been mmaped, such as libraries
Shmem
Total memory used by shared memory (shmem) and tmpfs
ShmemHugePages
Memory used by shared memory (shmem) and tmpfs allocated
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with huge pages
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ShmemPmdMapped
Shared memory mapped into userspace with huge pages
KReclaimable
Kernel allocations that the kernel will attempt to reclaim
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under memory pressure. Includes SReclaimable (below), and other
direct allocations with a shrinker.
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Slab
in-kernel data structures cache
SReclaimable
Part of Slab, that might be reclaimed, such as caches
SUnreclaim
Part of Slab, that cannot be reclaimed on memory pressure
PageTables
amount of memory dedicated to the lowest level of page
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tables.
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NFS_Unstable
NFS pages sent to the server, but not yet committed to stable
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storage
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Bounce
Memory used for block device "bounce buffers"
WritebackTmp
Memory used by FUSE for temporary writeback buffers
CommitLimit
Based on the overcommit ratio ('vm.overcommit_ratio'),
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this is the total amount of memory currently available to
be allocated on the system. This limit is only adhered to
if strict overcommit accounting is enabled (mode 2 in
'vm.overcommit_memory').
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The CommitLimit is calculated with the following formula::
CommitLimit = ([total RAM pages] - [total huge TLB pages]) *
overcommit_ratio / 100 + [total swap pages]
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For example, on a system with 1G of physical RAM and 7G
of swap with a `vm.overcommit_ratio`
yield a CommitLimit of 7.3G.
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For more details, see the memory overcommit documentation
in vm/overcommit-accounting.
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Committed_AS
The amount of memory presently allocated on the system.
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The committed memory is a sum of all of the memory which
has been allocated by processes, even if it has not been
"used" by them as of yet. A process which malloc()'s 1G
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of memory, but only touches 300M of it will show up as
using 1G. This 1G is memory which has been "committed" to
by the VM and can be used at any time by the allocating
application. With strict overcommit enabled on the system
(mode 2 in 'vm.overcommit_memory'),allocations which would
exceed the CommitLimit (detailed above) will not be permitted.
This is useful if one needs to guarantee that processes will
not fail due to lack of memory once that memory has been
successfully allocated.
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VmallocTotal
total size of vmalloc memory area
VmallocUsed
amount of vmalloc area which is used
VmallocChunk
largest contiguous block of vmalloc area which is free
Percpu
Memory allocated to the percpu allocator used to back percpu
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allocations. This stat excludes the cost of metadata.
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vmallocinfo
~~~~~~~~~~~
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Provides information about vmalloced/vmaped areas. One line per area,
containing the virtual address range of the area, size in bytes,
caller information of the creator, and optional information depending
on the kind of area :
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========== ===================================================
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pages=nr number of pages
phys=addr if a physical address was specified
ioremap I/O mapping (ioremap() and friends)
vmalloc vmalloc() area
vmap vmap()ed pages
user VM_USERMAP area
vpages buffer for pages pointers was vmalloced (huge area)
N<node>=nr (Only on NUMA kernels)
Number of pages allocated on memory node <node>
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========== ===================================================
::
> cat /proc/vmallocinfo
0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
/0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
/0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
phys=7fee8000 ioremap
0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
phys=7fee7000 ioremap
0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
/0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
pages=2 vmalloc N1=2
0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
/0x130 [x_tables] pages=4 vmalloc N0=4
0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
pages=14 vmalloc N2=14
0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
pages=4 vmalloc N1=4
0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
pages=2 vmalloc N1=2
0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
pages=10 vmalloc N0=10
softirqs
~~~~~~~~
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Provides counts of softirq handlers serviced since boot time, for each cpu.
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::
> cat /proc/softirqs
CPU0 CPU1 CPU2 CPU3
HI: 0 0 0 0
TIMER: 27166 27120 27097 27034
NET_TX: 0 0 0 17
NET_RX: 42 0 0 39
BLOCK: 0 0 107 1121
TASKLET: 0 0 0 290
SCHED: 27035 26983 26971 26746
HRTIMER: 0 0 0 0
RCU: 1678 1769 2178 2250
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1.3 IDE devices in /proc/ide
----------------------------
The subdirectory /proc/ide contains information about all IDE devices of which
the kernel is aware. There is one subdirectory for each IDE controller, the
file drivers and a link for each IDE device, pointing to the device directory
in the controller specific subtree.
The file drivers contains general information about the drivers used for the
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IDE devices::
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> cat /proc/ide/drivers
ide-cdrom version 4.53
ide-disk version 1.08
More detailed information can be found in the controller specific
subdirectories. These are named ide0, ide1 and so on. Each of these
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directories contains the files shown in table 1-6.
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.. table :: Table 1-6: IDE controller info in /proc/ide/ide?
======= =======================================
File Content
======= =======================================
channel IDE channel (0 or 1)
config Configuration (only for PCI/IDE bridge)
mate Mate name
model Type/Chipset of IDE controller
======= =======================================
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Each device connected to a controller has a separate subdirectory in the
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controllers directory. The files listed in table 1-7 are contained in these
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directories.
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.. table :: Table 1-7: IDE device information
================ ==========================================
File Content
================ ==========================================
cache The cache
capacity Capacity of the medium (in 512Byte blocks)
driver driver and version
geometry physical and logical geometry
identify device identify block
media media type
model device identifier
settings device setup
smart_thresholds IDE disk management thresholds
smart_values IDE disk management values
================ ==========================================
The most interesting file is `` settings `` . This file contains a nice
overview of the drive parameters::
# cat /proc/ide/ide0/hda/settings
name value min max mode
---- ----- --- --- ----
bios_cyl 526 0 65535 rw
bios_head 255 0 255 rw
bios_sect 63 0 63 rw
breada_readahead 4 0 127 rw
bswap 0 0 1 r
file_readahead 72 0 2097151 rw
io_32bit 0 0 3 rw
keepsettings 0 0 1 rw
max_kb_per_request 122 1 127 rw
multcount 0 0 8 rw
nice1 1 0 1 rw
nowerr 0 0 1 rw
pio_mode write-only 0 255 w
slow 0 0 1 rw
unmaskirq 0 0 1 rw
using_dma 0 0 1 rw
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1.4 Networking info in /proc/net
--------------------------------
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The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
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additional values you get for IP version 6 if you configure the kernel to
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support this. Table 1-9 lists the files and their meaning.
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.. table :: Table 1-8: IPv6 info in /proc/net
========== =====================================================
File Content
========== =====================================================
udp6 UDP sockets (IPv6)
tcp6 TCP sockets (IPv6)
raw6 Raw device statistics (IPv6)
igmp6 IP multicast addresses, which this host joined (IPv6)
if_inet6 List of IPv6 interface addresses
ipv6_route Kernel routing table for IPv6
rt6_stats Global IPv6 routing tables statistics
sockstat6 Socket statistics (IPv6)
snmp6 Snmp data (IPv6)
========== =====================================================
.. table :: Table 1-9: Network info in /proc/net
============= ================================================================
File Content
============= ================================================================
arp Kernel ARP table
dev network devices with statistics
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dev_mcast the Layer2 multicast groups a device is listening too
(interface index, label, number of references, number of bound
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addresses).
dev_stat network device status
ip_fwchains Firewall chain linkage
ip_fwnames Firewall chain names
ip_masq Directory containing the masquerading tables
ip_masquerade Major masquerading table
netstat Network statistics
raw raw device statistics
route Kernel routing table
rpc Directory containing rpc info
rt_cache Routing cache
snmp SNMP data
sockstat Socket statistics
tcp TCP sockets
udp UDP sockets
unix UNIX domain sockets
wireless Wireless interface data (Wavelan etc)
igmp IP multicast addresses, which this host joined
psched Global packet scheduler parameters.
netlink List of PF_NETLINK sockets
ip_mr_vifs List of multicast virtual interfaces
ip_mr_cache List of multicast routing cache
============= ================================================================
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You can use this information to see which network devices are available in
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your system and how much traffic was routed over those devices::
> cat /proc/net/dev
Inter-|Receive |[...
face |bytes packets errs drop fifo frame compressed multicast|[...
lo: 908188 5596 0 0 0 0 0 0 [...
ppp0:15475140 20721 410 0 0 410 0 0 [...
eth0: 614530 7085 0 0 0 0 0 1 [...
...] Transmit
...] bytes packets errs drop fifo colls carrier compressed
...] 908188 5596 0 0 0 0 0 0
...] 1375103 17405 0 0 0 0 0 0
...] 1703981 5535 0 0 0 3 0 0
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2010-04-23 02:08:02 +04:00
In addition, each Channel Bond interface has its own directory. For
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example, the bond0 device will have a directory called /proc/net/bond0/.
It will contain information that is specific to that bond, such as the
current slaves of the bond, the link status of the slaves, and how
many times the slaves link has failed.
1.5 SCSI info
-------------
If you have a SCSI host adapter in your system, you'll find a subdirectory
named after the driver for this adapter in /proc/scsi. You'll also see a list
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of all recognized SCSI devices in /proc/scsi::
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>cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: IBM Model: DGHS09U Rev: 03E0
Type: Direct-Access ANSI SCSI revision: 03
Host: scsi0 Channel: 00 Id: 06 Lun: 00
Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
Type: CD-ROM ANSI SCSI revision: 02
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The directory named after the driver has one file for each adapter found in
the system. These files contain information about the controller, including
the used IRQ and the IO address range. The amount of information shown is
dependent on the adapter you use. The example shows the output for an Adaptec
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AHA-2940 SCSI adapter::
> cat /proc/scsi/aic7xxx/0
Adaptec AIC7xxx driver version: 5.1.19/3.2.4
Compile Options:
TCQ Enabled By Default : Disabled
AIC7XXX_PROC_STATS : Disabled
AIC7XXX_RESET_DELAY : 5
Adapter Configuration:
SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
Ultra Wide Controller
PCI MMAPed I/O Base: 0xeb001000
Adapter SEEPROM Config: SEEPROM found and used.
Adaptec SCSI BIOS: Enabled
IRQ: 10
SCBs: Active 0, Max Active 2,
Allocated 15, HW 16, Page 255
Interrupts: 160328
BIOS Control Word: 0x18b6
Adapter Control Word: 0x005b
Extended Translation: Enabled
Disconnect Enable Flags: 0xffff
Ultra Enable Flags: 0x0001
Tag Queue Enable Flags: 0x0000
Ordered Queue Tag Flags: 0x0000
Default Tag Queue Depth: 8
Tagged Queue By Device array for aic7xxx host instance 0:
{255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
Actual queue depth per device for aic7xxx host instance 0:
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
Statistics:
(scsi0:0:0:0)
Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
Total transfers 160151 (74577 reads and 85574 writes)
(scsi0:0:6:0)
Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
Total transfers 0 (0 reads and 0 writes)
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1.6 Parallel port info in /proc/parport
---------------------------------------
The directory /proc/parport contains information about the parallel ports of
your system. It has one subdirectory for each port, named after the port
number (0,1,2,...).
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These directories contain the four files shown in Table 1-10.
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.. table :: Table 1-10: Files in /proc/parport
========= ====================================================================
File Content
========= ====================================================================
autoprobe Any IEEE-1284 device ID information that has been acquired.
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devices list of the device drivers using that port. A + will appear by the
name of the device currently using the port (it might not appear
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against any).
hardware Parallel port's base address, IRQ line and DMA channel.
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irq IRQ that parport is using for that port. This is in a separate
file to allow you to alter it by writing a new value in (IRQ
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number or none).
========= ====================================================================
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1.7 TTY info in /proc/tty
-------------------------
Information about the available and actually used tty's can be found in the
directory /proc/tty.You'll find entries for drivers and line disciplines in
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this directory, as shown in Table 1-11.
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.. table :: Table 1-11: Files in /proc/tty
============= ==============================================
File Content
============= ==============================================
drivers list of drivers and their usage
ldiscs registered line disciplines
driver/serial usage statistic and status of single tty lines
============= ==============================================
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To see which tty's are currently in use, you can simply look into the file
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/proc/tty/drivers::
> cat /proc/tty/drivers
pty_slave /dev/pts 136 0-255 pty:slave
pty_master /dev/ptm 128 0-255 pty:master
pty_slave /dev/ttyp 3 0-255 pty:slave
pty_master /dev/pty 2 0-255 pty:master
serial /dev/cua 5 64-67 serial:callout
serial /dev/ttyS 4 64-67 serial
/dev/tty0 /dev/tty0 4 0 system:vtmaster
/dev/ptmx /dev/ptmx 5 2 system
/dev/console /dev/console 5 1 system:console
/dev/tty /dev/tty 5 0 system:/dev/tty
unknown /dev/tty 4 1-63 console
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1.8 Miscellaneous kernel statistics in /proc/stat
-------------------------------------------------
Various pieces of information about kernel activity are available in the
/proc/stat file. All of the numbers reported in this file are aggregates
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since the system first booted. For a quick look, simply cat the file::
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> cat /proc/stat
2015-03-30 16:49:26 +03:00
cpu 2255 34 2290 22625563 6290 127 456 0 0 0
cpu0 1132 34 1441 11311718 3675 127 438 0 0 0
cpu1 1123 0 849 11313845 2614 0 18 0 0 0
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intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...]
ctxt 1990473
btime 1062191376
processes 2915
procs_running 1
procs_blocked 0
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softirq 183433 0 21755 12 39 1137 231 21459 2263
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The very first "cpu" line aggregates the numbers in all of the other "cpuN"
lines. These numbers identify the amount of time the CPU has spent performing
different kinds of work. Time units are in USER_HZ (typically hundredths of a
second). The meanings of the columns are as follows, from left to right:
- user: normal processes executing in user mode
- nice: niced processes executing in user mode
- system: processes executing in kernel mode
- idle: twiddling thumbs
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- iowait: In a word, iowait stands for waiting for I/O to complete. But there
are several problems:
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2016-10-26 05:41:28 +03:00
1. Cpu will not wait for I/O to complete, iowait is the time that a task is
waiting for I/O to complete. When cpu goes into idle state for
outstanding task io, another task will be scheduled on this CPU.
2. In a multi-core CPU, the task waiting for I/O to complete is not running
on any CPU, so the iowait of each CPU is difficult to calculate.
3. The value of iowait field in /proc/stat will decrease in certain
conditions.
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2016-10-26 05:41:28 +03:00
So, the iowait is not reliable by reading from /proc/stat.
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- irq: servicing interrupts
- softirq: servicing softirqs
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- steal: involuntary wait
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- guest: running a normal guest
- guest_nice: running a niced guest
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The "intr" line gives counts of interrupts serviced since boot time, for each
of the possible system interrupts. The first column is the total of all
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interrupts serviced including unnumbered architecture specific interrupts;
each subsequent column is the total for that particular numbered interrupt.
Unnumbered interrupts are not shown, only summed into the total.
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The "ctxt" line gives the total number of context switches across all CPUs.
The "btime" line gives the time at which the system booted, in seconds since
the Unix epoch.
The "processes" line gives the number of processes and threads created, which
includes (but is not limited to) those created by calls to the fork() and
clone() system calls.
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The "procs_running" line gives the total number of threads that are
running or ready to run (i.e., the total number of runnable threads).
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The "procs_blocked" line gives the number of processes currently blocked,
waiting for I/O to complete.
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The "softirq" line gives counts of softirqs serviced since boot time, for each
of the possible system softirqs. The first column is the total of all
softirqs serviced; each subsequent column is the total for that particular
softirq.
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2008-01-29 08:19:52 +03:00
1.9 Ext4 file system parameters
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-------------------------------
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Information about mounted ext4 file systems can be found in
/proc/fs/ext4. Each mounted filesystem will have a directory in
/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
/proc/fs/ext4/dm-0). The files in each per-device directory are shown
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in Table 1-12, below.
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.. table :: Table 1-12: Files in /proc/fs/ext4/<devname>
============== ==========================================================
File Content
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mb_groups details of multiblock allocator buddy cache of free blocks
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============== ==========================================================
2008-10-10 07:21:54 +04:00
2010-11-04 18:20:24 +03:00
2.0 /proc/consoles
------------------
Shows registered system console lines.
To see which character device lines are currently used for the system console
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/dev/console, you may simply look into the file /proc/consoles::
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> cat /proc/consoles
tty0 -WU (ECp) 4:7
ttyS0 -W- (Ep) 4:64
The columns are:
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+--------------------+-------------------------------------------------------+
| device | name of the device |
+====================+=======================================================+
| operations | * R = can do read operations |
| | * W = can do write operations |
| | * U = can do unblank |
+--------------------+-------------------------------------------------------+
| flags | * E = it is enabled |
| | * C = it is preferred console |
| | * B = it is primary boot console |
| | * p = it is used for printk buffer |
| | * b = it is not a TTY but a Braille device |
| | * a = it is safe to use when cpu is offline |
+--------------------+-------------------------------------------------------+
| major:minor | major and minor number of the device separated by a |
| | colon |
+--------------------+-------------------------------------------------------+
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Summary
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-------
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The /proc file system serves information about the running system. It not only
allows access to process data but also allows you to request the kernel status
by reading files in the hierarchy.
The directory structure of /proc reflects the types of information and makes
it easy, if not obvious, where to look for specific data.
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Chapter 2: Modifying System Parameters
======================================
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In This Chapter
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---------------
2005-04-17 02:20:36 +04:00
* Modifying kernel parameters by writing into files found in /proc/sys
* Exploring the files which modify certain parameters
* Review of the /proc/sys file tree
2020-02-17 19:12:18 +03:00
------------------------------------------------------------------------------
2005-04-17 02:20:36 +04:00
A very interesting part of /proc is the directory /proc/sys. This is not only
a source of information, it also allows you to change parameters within the
kernel. Be very careful when attempting this. You can optimize your system,
but you can also cause it to crash. Never alter kernel parameters on a
production system. Set up a development machine and test to make sure that
everything works the way you want it to. You may have no alternative but to
reboot the machine once an error has been made.
To change a value, simply echo the new value into the file. An example is
given below in the section on the file system data. You need to be root to do
this. You can create your own boot script to perform this every time your
system boots.
The files in /proc/sys can be used to fine tune and monitor miscellaneous and
general things in the operation of the Linux kernel. Since some of the files
can inadvertently disrupt your system, it is advisable to read both
documentation and source before actually making adjustments. In any case, be
very careful when writing to any of these files. The entries in /proc may
change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
review the kernel documentation in the directory /usr/src/linux/Documentation.
This chapter is heavily based on the documentation included in the pre 2.2
kernels, and became part of it in version 2.2.1 of the Linux kernel.
2019-04-22 22:48:00 +03:00
Please see: Documentation/admin-guide/sysctl/ directory for descriptions of these
2009-01-16 00:50:42 +03:00
entries.
2006-01-08 12:00:39 +03:00
2009-04-03 03:57:20 +04:00
Summary
2020-02-17 19:12:18 +03:00
-------
2009-04-03 03:57:20 +04:00
Certain aspects of kernel behavior can be modified at runtime, without the
need to recompile the kernel, or even to reboot the system. The files in the
/proc/sys tree can not only be read, but also modified. You can use the echo
command to write value into these files, thereby changing the default settings
of the kernel.
2006-01-08 12:00:39 +03:00
2020-02-17 19:12:18 +03:00
Chapter 3: Per-process Parameters
=================================
2005-04-17 02:20:36 +04:00
2012-11-13 05:53:04 +04:00
3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
oom: badness heuristic rewrite
This a complete rewrite of the oom killer's badness() heuristic which is
used to determine which task to kill in oom conditions. The goal is to
make it as simple and predictable as possible so the results are better
understood and we end up killing the task which will lead to the most
memory freeing while still respecting the fine-tuning from userspace.
Instead of basing the heuristic on mm->total_vm for each task, the task's
rss and swap space is used instead. This is a better indication of the
amount of memory that will be freeable if the oom killed task is chosen
and subsequently exits. This helps specifically in cases where KDE or
GNOME is chosen for oom kill on desktop systems instead of a memory
hogging task.
The baseline for the heuristic is a proportion of memory that each task is
currently using in memory plus swap compared to the amount of "allowable"
memory. "Allowable," in this sense, means the system-wide resources for
unconstrained oom conditions, the set of mempolicy nodes, the mems
attached to current's cpuset, or a memory controller's limit. The
proportion is given on a scale of 0 (never kill) to 1000 (always kill),
roughly meaning that if a task has a badness() score of 500 that the task
consumes approximately 50% of allowable memory resident in RAM or in swap
space.
The proportion is always relative to the amount of "allowable" memory and
not the total amount of RAM systemwide so that mempolicies and cpusets may
operate in isolation; they shall not need to know the true size of the
machine on which they are running if they are bound to a specific set of
nodes or mems, respectively.
Root tasks are given 3% extra memory just like __vm_enough_memory()
provides in LSMs. In the event of two tasks consuming similar amounts of
memory, it is generally better to save root's task.
Because of the change in the badness() heuristic's baseline, it is also
necessary to introduce a new user interface to tune it. It's not possible
to redefine the meaning of /proc/pid/oom_adj with a new scale since the
ABI cannot be changed for backward compatability. Instead, a new tunable,
/proc/pid/oom_score_adj, is added that ranges from -1000 to +1000. It may
be used to polarize the heuristic such that certain tasks are never
considered for oom kill while others may always be considered. The value
is added directly into the badness() score so a value of -500, for
example, means to discount 50% of its memory consumption in comparison to
other tasks either on the system, bound to the mempolicy, in the cpuset,
or sharing the same memory controller.
/proc/pid/oom_adj is changed so that its meaning is rescaled into the
units used by /proc/pid/oom_score_adj, and vice versa. Changing one of
these per-task tunables will rescale the value of the other to an
equivalent meaning. Although /proc/pid/oom_adj was originally defined as
a bitshift on the badness score, it now shares the same linear growth as
/proc/pid/oom_score_adj but with different granularity. This is required
so the ABI is not broken with userspace applications and allows oom_adj to
be deprecated for future removal.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-10 04:19:46 +04:00
--------------------------------------------------------------------------------
2012-11-13 05:53:04 +04:00
These file can be used to adjust the badness heuristic used to select which
oom: badness heuristic rewrite
This a complete rewrite of the oom killer's badness() heuristic which is
used to determine which task to kill in oom conditions. The goal is to
make it as simple and predictable as possible so the results are better
understood and we end up killing the task which will lead to the most
memory freeing while still respecting the fine-tuning from userspace.
Instead of basing the heuristic on mm->total_vm for each task, the task's
rss and swap space is used instead. This is a better indication of the
amount of memory that will be freeable if the oom killed task is chosen
and subsequently exits. This helps specifically in cases where KDE or
GNOME is chosen for oom kill on desktop systems instead of a memory
hogging task.
The baseline for the heuristic is a proportion of memory that each task is
currently using in memory plus swap compared to the amount of "allowable"
memory. "Allowable," in this sense, means the system-wide resources for
unconstrained oom conditions, the set of mempolicy nodes, the mems
attached to current's cpuset, or a memory controller's limit. The
proportion is given on a scale of 0 (never kill) to 1000 (always kill),
roughly meaning that if a task has a badness() score of 500 that the task
consumes approximately 50% of allowable memory resident in RAM or in swap
space.
The proportion is always relative to the amount of "allowable" memory and
not the total amount of RAM systemwide so that mempolicies and cpusets may
operate in isolation; they shall not need to know the true size of the
machine on which they are running if they are bound to a specific set of
nodes or mems, respectively.
Root tasks are given 3% extra memory just like __vm_enough_memory()
provides in LSMs. In the event of two tasks consuming similar amounts of
memory, it is generally better to save root's task.
Because of the change in the badness() heuristic's baseline, it is also
necessary to introduce a new user interface to tune it. It's not possible
to redefine the meaning of /proc/pid/oom_adj with a new scale since the
ABI cannot be changed for backward compatability. Instead, a new tunable,
/proc/pid/oom_score_adj, is added that ranges from -1000 to +1000. It may
be used to polarize the heuristic such that certain tasks are never
considered for oom kill while others may always be considered. The value
is added directly into the badness() score so a value of -500, for
example, means to discount 50% of its memory consumption in comparison to
other tasks either on the system, bound to the mempolicy, in the cpuset,
or sharing the same memory controller.
/proc/pid/oom_adj is changed so that its meaning is rescaled into the
units used by /proc/pid/oom_score_adj, and vice versa. Changing one of
these per-task tunables will rescale the value of the other to an
equivalent meaning. Although /proc/pid/oom_adj was originally defined as
a bitshift on the badness score, it now shares the same linear growth as
/proc/pid/oom_score_adj but with different granularity. This is required
so the ABI is not broken with userspace applications and allows oom_adj to
be deprecated for future removal.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-10 04:19:46 +04:00
process gets killed in out of memory conditions.
The badness heuristic assigns a value to each candidate task ranging from 0
(never kill) to 1000 (always kill) to determine which process is targeted. The
units are roughly a proportion along that range of allowed memory the process
may allocate from based on an estimation of its current memory and swap use.
For example, if a task is using all allowed memory, its badness score will be
1000. If it is using half of its allowed memory, its score will be 500.
mm, oom: base root bonus on current usage
A 3% of system memory bonus is sometimes too excessive in comparison to
other processes.
With commit a63d83f427fb ("oom: badness heuristic rewrite"), the OOM
killer tries to avoid killing privileged tasks by subtracting 3% of
overall memory (system or cgroup) from their per-task consumption. But
as a result, all root tasks that consume less than 3% of overall memory
are considered equal, and so it only takes 33+ privileged tasks pushing
the system out of memory for the OOM killer to do something stupid and
kill dhclient or other root-owned processes. For example, on a 32G
machine it can't tell the difference between the 1M agetty and the 10G
fork bomb member.
The changelog describes this 3% boost as the equivalent to the global
overcommit limit being 3% higher for privileged tasks, but this is not
the same as discounting 3% of overall memory from _every privileged task
individually_ during OOM selection.
Replace the 3% of system memory bonus with a 3% of current memory usage
bonus.
By giving root tasks a bonus that is proportional to their actual size,
they remain comparable even when relatively small. In the example
above, the OOM killer will discount the 1M agetty's 256 badness points
down to 179, and the 10G fork bomb's 262144 points down to 183500 points
and make the right choice, instead of discounting both to 0 and killing
agetty because it's first in the task list.
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-31 03:46:11 +04:00
There is an additional factor included in the badness score: the current memory
and swap usage is discounted by 3% for root processes.
oom: badness heuristic rewrite
This a complete rewrite of the oom killer's badness() heuristic which is
used to determine which task to kill in oom conditions. The goal is to
make it as simple and predictable as possible so the results are better
understood and we end up killing the task which will lead to the most
memory freeing while still respecting the fine-tuning from userspace.
Instead of basing the heuristic on mm->total_vm for each task, the task's
rss and swap space is used instead. This is a better indication of the
amount of memory that will be freeable if the oom killed task is chosen
and subsequently exits. This helps specifically in cases where KDE or
GNOME is chosen for oom kill on desktop systems instead of a memory
hogging task.
The baseline for the heuristic is a proportion of memory that each task is
currently using in memory plus swap compared to the amount of "allowable"
memory. "Allowable," in this sense, means the system-wide resources for
unconstrained oom conditions, the set of mempolicy nodes, the mems
attached to current's cpuset, or a memory controller's limit. The
proportion is given on a scale of 0 (never kill) to 1000 (always kill),
roughly meaning that if a task has a badness() score of 500 that the task
consumes approximately 50% of allowable memory resident in RAM or in swap
space.
The proportion is always relative to the amount of "allowable" memory and
not the total amount of RAM systemwide so that mempolicies and cpusets may
operate in isolation; they shall not need to know the true size of the
machine on which they are running if they are bound to a specific set of
nodes or mems, respectively.
Root tasks are given 3% extra memory just like __vm_enough_memory()
provides in LSMs. In the event of two tasks consuming similar amounts of
memory, it is generally better to save root's task.
Because of the change in the badness() heuristic's baseline, it is also
necessary to introduce a new user interface to tune it. It's not possible
to redefine the meaning of /proc/pid/oom_adj with a new scale since the
ABI cannot be changed for backward compatability. Instead, a new tunable,
/proc/pid/oom_score_adj, is added that ranges from -1000 to +1000. It may
be used to polarize the heuristic such that certain tasks are never
considered for oom kill while others may always be considered. The value
is added directly into the badness() score so a value of -500, for
example, means to discount 50% of its memory consumption in comparison to
other tasks either on the system, bound to the mempolicy, in the cpuset,
or sharing the same memory controller.
/proc/pid/oom_adj is changed so that its meaning is rescaled into the
units used by /proc/pid/oom_score_adj, and vice versa. Changing one of
these per-task tunables will rescale the value of the other to an
equivalent meaning. Although /proc/pid/oom_adj was originally defined as
a bitshift on the badness score, it now shares the same linear growth as
/proc/pid/oom_score_adj but with different granularity. This is required
so the ABI is not broken with userspace applications and allows oom_adj to
be deprecated for future removal.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-10 04:19:46 +04:00
The amount of "allowed" memory depends on the context in which the oom killer
was called. If it is due to the memory assigned to the allocating task's cpuset
being exhausted, the allowed memory represents the set of mems assigned to that
cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed
memory represents the set of mempolicy nodes. If it is due to a memory
limit (or swap limit) being reached, the allowed memory is that configured
limit. Finally, if it is due to the entire system being out of memory, the
allowed memory represents all allocatable resources.
The value of /proc/<pid>/oom_score_adj is added to the badness score before it
is used to determine which task to kill. Acceptable values range from -1000
(OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to
polarize the preference for oom killing either by always preferring a certain
task or completely disabling it. The lowest possible value, -1000, is
equivalent to disabling oom killing entirely for that task since it will always
report a badness score of 0.
Consequently, it is very simple for userspace to define the amount of memory to
consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for
example, is roughly equivalent to allowing the remainder of tasks sharing the
same system, cpuset, mempolicy, or memory controller resources to use at least
50% more memory. A value of -500, on the other hand, would be roughly
equivalent to discounting 50% of the task's allowed memory from being considered
as scoring against the task.
2012-11-13 05:53:04 +04:00
For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
be used to tune the badness score. Its acceptable values range from -16
(OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
(OOM_DISABLE) to disable oom killing entirely for that task. Its value is
scaled linearly with /proc/<pid>/oom_score_adj.
2011-01-14 02:46:05 +03:00
The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
requires CAP_SYS_RESOURCE.
oom: badness heuristic rewrite
This a complete rewrite of the oom killer's badness() heuristic which is
used to determine which task to kill in oom conditions. The goal is to
make it as simple and predictable as possible so the results are better
understood and we end up killing the task which will lead to the most
memory freeing while still respecting the fine-tuning from userspace.
Instead of basing the heuristic on mm->total_vm for each task, the task's
rss and swap space is used instead. This is a better indication of the
amount of memory that will be freeable if the oom killed task is chosen
and subsequently exits. This helps specifically in cases where KDE or
GNOME is chosen for oom kill on desktop systems instead of a memory
hogging task.
The baseline for the heuristic is a proportion of memory that each task is
currently using in memory plus swap compared to the amount of "allowable"
memory. "Allowable," in this sense, means the system-wide resources for
unconstrained oom conditions, the set of mempolicy nodes, the mems
attached to current's cpuset, or a memory controller's limit. The
proportion is given on a scale of 0 (never kill) to 1000 (always kill),
roughly meaning that if a task has a badness() score of 500 that the task
consumes approximately 50% of allowable memory resident in RAM or in swap
space.
The proportion is always relative to the amount of "allowable" memory and
not the total amount of RAM systemwide so that mempolicies and cpusets may
operate in isolation; they shall not need to know the true size of the
machine on which they are running if they are bound to a specific set of
nodes or mems, respectively.
Root tasks are given 3% extra memory just like __vm_enough_memory()
provides in LSMs. In the event of two tasks consuming similar amounts of
memory, it is generally better to save root's task.
Because of the change in the badness() heuristic's baseline, it is also
necessary to introduce a new user interface to tune it. It's not possible
to redefine the meaning of /proc/pid/oom_adj with a new scale since the
ABI cannot be changed for backward compatability. Instead, a new tunable,
/proc/pid/oom_score_adj, is added that ranges from -1000 to +1000. It may
be used to polarize the heuristic such that certain tasks are never
considered for oom kill while others may always be considered. The value
is added directly into the badness() score so a value of -500, for
example, means to discount 50% of its memory consumption in comparison to
other tasks either on the system, bound to the mempolicy, in the cpuset,
or sharing the same memory controller.
/proc/pid/oom_adj is changed so that its meaning is rescaled into the
units used by /proc/pid/oom_score_adj, and vice versa. Changing one of
these per-task tunables will rescale the value of the other to an
equivalent meaning. Although /proc/pid/oom_adj was originally defined as
a bitshift on the badness score, it now shares the same linear growth as
/proc/pid/oom_score_adj but with different granularity. This is required
so the ABI is not broken with userspace applications and allows oom_adj to
be deprecated for future removal.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-10 04:19:46 +04:00
Caveat: when a parent task is selected, the oom killer will sacrifice any first
2011-03-31 05:57:33 +04:00
generation children with separate address spaces instead, if possible. This
oom: badness heuristic rewrite
This a complete rewrite of the oom killer's badness() heuristic which is
used to determine which task to kill in oom conditions. The goal is to
make it as simple and predictable as possible so the results are better
understood and we end up killing the task which will lead to the most
memory freeing while still respecting the fine-tuning from userspace.
Instead of basing the heuristic on mm->total_vm for each task, the task's
rss and swap space is used instead. This is a better indication of the
amount of memory that will be freeable if the oom killed task is chosen
and subsequently exits. This helps specifically in cases where KDE or
GNOME is chosen for oom kill on desktop systems instead of a memory
hogging task.
The baseline for the heuristic is a proportion of memory that each task is
currently using in memory plus swap compared to the amount of "allowable"
memory. "Allowable," in this sense, means the system-wide resources for
unconstrained oom conditions, the set of mempolicy nodes, the mems
attached to current's cpuset, or a memory controller's limit. The
proportion is given on a scale of 0 (never kill) to 1000 (always kill),
roughly meaning that if a task has a badness() score of 500 that the task
consumes approximately 50% of allowable memory resident in RAM or in swap
space.
The proportion is always relative to the amount of "allowable" memory and
not the total amount of RAM systemwide so that mempolicies and cpusets may
operate in isolation; they shall not need to know the true size of the
machine on which they are running if they are bound to a specific set of
nodes or mems, respectively.
Root tasks are given 3% extra memory just like __vm_enough_memory()
provides in LSMs. In the event of two tasks consuming similar amounts of
memory, it is generally better to save root's task.
Because of the change in the badness() heuristic's baseline, it is also
necessary to introduce a new user interface to tune it. It's not possible
to redefine the meaning of /proc/pid/oom_adj with a new scale since the
ABI cannot be changed for backward compatability. Instead, a new tunable,
/proc/pid/oom_score_adj, is added that ranges from -1000 to +1000. It may
be used to polarize the heuristic such that certain tasks are never
considered for oom kill while others may always be considered. The value
is added directly into the badness() score so a value of -500, for
example, means to discount 50% of its memory consumption in comparison to
other tasks either on the system, bound to the mempolicy, in the cpuset,
or sharing the same memory controller.
/proc/pid/oom_adj is changed so that its meaning is rescaled into the
units used by /proc/pid/oom_score_adj, and vice versa. Changing one of
these per-task tunables will rescale the value of the other to an
equivalent meaning. Although /proc/pid/oom_adj was originally defined as
a bitshift on the badness score, it now shares the same linear growth as
/proc/pid/oom_score_adj but with different granularity. This is required
so the ABI is not broken with userspace applications and allows oom_adj to
be deprecated for future removal.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-10 04:19:46 +04:00
avoids servers and important system daemons from being killed and loses the
minimal amount of work.
2009-01-30 01:25:09 +03:00
2009-04-03 03:57:20 +04:00
3.2 /proc/<pid>/oom_score - Display current oom-killer score
2006-09-29 12:59:45 +04:00
-------------------------------------------------------------
This file can be used to check the current score used by the oom-killer is for
2012-11-13 05:53:04 +04:00
any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which
process should be killed in an out-of-memory situation.
2007-03-05 11:30:54 +03:00
2009-04-03 03:57:20 +04:00
3.3 /proc/<pid>/io - Display the IO accounting fields
2007-03-05 11:30:54 +03:00
-------------------------------------------------------
This file contains IO statistics for each running process
Example
2020-02-17 19:12:18 +03:00
~~~~~~~
::
2007-03-05 11:30:54 +03:00
2020-02-17 19:12:18 +03:00
test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
[1] 3828
2007-03-05 11:30:54 +03:00
2020-02-17 19:12:18 +03:00
test:/tmp # cat /proc/3828/io
rchar: 323934931
wchar: 323929600
syscr: 632687
syscw: 632675
read_bytes: 0
write_bytes: 323932160
cancelled_write_bytes: 0
2007-03-05 11:30:54 +03:00
Description
2020-02-17 19:12:18 +03:00
~~~~~~~~~~~
2007-03-05 11:30:54 +03:00
rchar
2020-02-17 19:12:18 +03:00
^^^^^
2007-03-05 11:30:54 +03:00
I/O counter: chars read
The number of bytes which this task has caused to be read from storage. This
is simply the sum of bytes which this process passed to read() and pread().
It includes things like tty IO and it is unaffected by whether or not actual
physical disk IO was required (the read might have been satisfied from
pagecache)
wchar
2020-02-17 19:12:18 +03:00
^^^^^
2007-03-05 11:30:54 +03:00
I/O counter: chars written
The number of bytes which this task has caused, or shall cause to be written
to disk. Similar caveats apply here as with rchar.
syscr
2020-02-17 19:12:18 +03:00
^^^^^
2007-03-05 11:30:54 +03:00
I/O counter: read syscalls
Attempt to count the number of read I/O operations, i.e. syscalls like read()
and pread().
syscw
2020-02-17 19:12:18 +03:00
^^^^^
2007-03-05 11:30:54 +03:00
I/O counter: write syscalls
Attempt to count the number of write I/O operations, i.e. syscalls like
write() and pwrite().
read_bytes
2020-02-17 19:12:18 +03:00
^^^^^^^^^^
2007-03-05 11:30:54 +03:00
I/O counter: bytes read
Attempt to count the number of bytes which this process really did cause to
be fetched from the storage layer. Done at the submit_bio() level, so it is
accurate for block-backed filesystems. <please add status regarding NFS and
CIFS at a later time>
write_bytes
2020-02-17 19:12:18 +03:00
^^^^^^^^^^^
2007-03-05 11:30:54 +03:00
I/O counter: bytes written
Attempt to count the number of bytes which this process caused to be sent to
the storage layer. This is done at page-dirtying time.
cancelled_write_bytes
2020-02-17 19:12:18 +03:00
^^^^^^^^^^^^^^^^^^^^^
2007-03-05 11:30:54 +03:00
The big inaccuracy here is truncate. If a process writes 1MB to a file and
then deletes the file, it will in fact perform no writeout. But it will have
been accounted as having caused 1MB of write.
In other words: The number of bytes which this process caused to not happen,
by truncating pagecache. A task can cause "negative" IO too. If this task
truncates some dirty pagecache, some IO which another task has been accounted
2010-04-23 02:08:02 +04:00
for (in its write_bytes) will not be happening. We _could_ just subtract that
2007-03-05 11:30:54 +03:00
from the truncating task's write_bytes, but there is information loss in doing
that.
2020-02-17 19:12:18 +03:00
.. Note ::
2007-03-05 11:30:54 +03:00
2020-02-17 19:12:18 +03:00
At its current implementation state, this is a bit racy on 32-bit machines:
if process A reads process B's /proc/pid/io while process B is updating one
of those 64-bit counters, process A could see an intermediate result.
2007-03-05 11:30:54 +03:00
More information about this can be found within the taskstats documentation in
Documentation/accounting.
2009-04-03 03:57:20 +04:00
3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
2007-07-19 12:48:31 +04:00
---------------------------------------------------------------
When a process is dumped, all anonymous memory is written to a core file as
long as the size of the core file isn't limited. But sometimes we don't want
2015-10-06 01:33:36 +03:00
to dump some memory segments, for example, huge shared memory or DAX.
Conversely, sometimes we want to save file-backed memory segments into a core
file, not only the individual files.
2007-07-19 12:48:31 +04:00
/proc/<pid>/coredump_filter allows you to customize which memory segments
will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
of memory types. If a bit of the bitmask is set, memory segments of the
corresponding memory type are dumped, otherwise they are not dumped.
2015-10-06 01:33:36 +03:00
The following 9 memory types are supported:
2020-02-17 19:12:18 +03:00
2007-07-19 12:48:31 +04:00
- (bit 0) anonymous private memory
- (bit 1) anonymous shared memory
- (bit 2) file-backed private memory
- (bit 3) file-backed shared memory
2008-09-13 13:33:10 +04:00
- (bit 4) ELF header pages in file-backed private memory areas (it is
2020-02-17 19:12:18 +03:00
effective only if the bit 2 is cleared)
coredump_filter: add hugepage dumping
Presently hugepage's vma has a VM_RESERVED flag in order not to be
swapped. But a VM_RESERVED vma isn't core dumped because this flag is
often used for some kernel vmas (e.g. vmalloc, sound related).
Thus hugepages are never dumped and it can't be debugged easily. Many
developers want hugepages to be included into core-dump.
However, We can't read generic VM_RESERVED area because this area is often
IO mapping area. then these area reading may change device state. it is
definitly undesiable side-effect.
So adding a hugepage specific bit to the coredump filter is better. It
will be able to hugepage core dumping and doesn't cause any side-effect to
any i/o devices.
In additional, libhugetlb use hugetlb private mapping pages as anonymous
page. Then, hugepage private mapping pages should be core dumped by
default.
Then, /proc/[pid]/core_dump_filter has two new bits.
- bit 5 mean hugetlb private mapping pages are dumped or not. (default: yes)
- bit 6 mean hugetlb shared mapping pages are dumped or not. (default: no)
I tested by following method.
% ulimit -c unlimited
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
%
% echo 0x43 > /proc/self/coredump_filter
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>
#include "hugetlbfs.h"
int main(int argc, char** argv){
char* p;
int ch;
int mmap_flags = MAP_SHARED;
int fd;
int nr_pages;
while((ch = getopt(argc, argv, "p")) != -1) {
switch (ch) {
case 'p':
mmap_flags &= ~MAP_SHARED;
mmap_flags |= MAP_PRIVATE;
break;
default:
/* nothing*/
break;
}
}
argc -= optind;
argv += optind;
if (argc == 0){
printf("need # of pages\n");
exit(1);
}
nr_pages = atoi(argv[0]);
if (nr_pages < 2) {
printf("nr_pages must >2\n");
exit(1);
}
fd = hugetlbfs_unlinked_fd();
p = mmap(NULL, nr_pages * gethugepagesize(),
PROT_READ|PROT_WRITE, mmap_flags, fd, 0);
sleep(2);
*(p + gethugepagesize()) = 1; /* COW */
sleep(2);
/* crash! */
*(int*)0 = 1;
return 0;
}
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Kawai Hidehiro <hidehiro.kawai.ez@hitachi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: William Irwin <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-19 07:27:08 +04:00
- (bit 5) hugetlb private memory
- (bit 6) hugetlb shared memory
2015-10-06 01:33:36 +03:00
- (bit 7) DAX private memory
- (bit 8) DAX shared memory
2007-07-19 12:48:31 +04:00
Note that MMIO pages such as frame buffer are never dumped and vDSO pages
are always dumped regardless of the bitmask status.
2015-10-06 01:33:36 +03:00
Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is
only affected by bit 5-6, and DAX is only affected by bits 7-8.
coredump_filter: add hugepage dumping
Presently hugepage's vma has a VM_RESERVED flag in order not to be
swapped. But a VM_RESERVED vma isn't core dumped because this flag is
often used for some kernel vmas (e.g. vmalloc, sound related).
Thus hugepages are never dumped and it can't be debugged easily. Many
developers want hugepages to be included into core-dump.
However, We can't read generic VM_RESERVED area because this area is often
IO mapping area. then these area reading may change device state. it is
definitly undesiable side-effect.
So adding a hugepage specific bit to the coredump filter is better. It
will be able to hugepage core dumping and doesn't cause any side-effect to
any i/o devices.
In additional, libhugetlb use hugetlb private mapping pages as anonymous
page. Then, hugepage private mapping pages should be core dumped by
default.
Then, /proc/[pid]/core_dump_filter has two new bits.
- bit 5 mean hugetlb private mapping pages are dumped or not. (default: yes)
- bit 6 mean hugetlb shared mapping pages are dumped or not. (default: no)
I tested by following method.
% ulimit -c unlimited
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
%
% echo 0x43 > /proc/self/coredump_filter
% ./crash_hugepage 50
% ./crash_hugepage 50 -p
% ls -lh
% gdb ./crash_hugepage core
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>
#include "hugetlbfs.h"
int main(int argc, char** argv){
char* p;
int ch;
int mmap_flags = MAP_SHARED;
int fd;
int nr_pages;
while((ch = getopt(argc, argv, "p")) != -1) {
switch (ch) {
case 'p':
mmap_flags &= ~MAP_SHARED;
mmap_flags |= MAP_PRIVATE;
break;
default:
/* nothing*/
break;
}
}
argc -= optind;
argv += optind;
if (argc == 0){
printf("need # of pages\n");
exit(1);
}
nr_pages = atoi(argv[0]);
if (nr_pages < 2) {
printf("nr_pages must >2\n");
exit(1);
}
fd = hugetlbfs_unlinked_fd();
p = mmap(NULL, nr_pages * gethugepagesize(),
PROT_READ|PROT_WRITE, mmap_flags, fd, 0);
sleep(2);
*(p + gethugepagesize()) = 1; /* COW */
sleep(2);
/* crash! */
*(int*)0 = 1;
return 0;
}
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Kawai Hidehiro <hidehiro.kawai.ez@hitachi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: William Irwin <wli@holomorphy.com>
Cc: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-19 07:27:08 +04:00
2015-10-06 01:33:36 +03:00
The default value of coredump_filter is 0x33; this means all anonymous memory
segments, ELF header pages and hugetlb private memory are dumped.
2007-07-19 12:48:31 +04:00
If you don't want to dump all shared memory segments attached to pid 1234,
2020-02-17 19:12:18 +03:00
write 0x31 to the process's proc file::
2007-07-19 12:48:31 +04:00
2015-10-06 01:33:36 +03:00
$ echo 0x31 > /proc/1234/coredump_filter
2007-07-19 12:48:31 +04:00
When a new process is created, the process inherits the bitmask status from its
parent. It is useful to set up coredump_filter before the program runs.
2020-02-17 19:12:18 +03:00
For example::
2007-07-19 12:48:31 +04:00
$ echo 0x7 > /proc/self/coredump_filter
$ ./some_program
2009-04-03 03:57:20 +04:00
3.5 /proc/<pid>/mountinfo - Information about mounts
2008-03-27 15:06:25 +03:00
--------------------------------------------------------
2020-02-17 19:12:18 +03:00
This file contains lines of the form::
2008-03-27 15:06:25 +03:00
2020-02-17 19:12:18 +03:00
36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
2008-03-27 15:06:25 +03:00
2020-02-17 19:12:18 +03:00
(1) mount ID: unique identifier of the mount (may be reused after umount)
(2) parent ID: ID of parent (or of self for the top of the mount tree)
(3) major:minor: value of st_dev for files on filesystem
(4) root: root of the mount within the filesystem
(5) mount point: mount point relative to the process's root
(6) mount options: per mount options
(7) optional fields: zero or more fields of the form "tag[:value]"
(8) separator: marks the end of the optional fields
(9) filesystem type: name of filesystem of the form "type[.subtype]"
(10) mount source: filesystem specific information or "none"
(11) super options: per super block options
2008-03-27 15:06:25 +03:00
Parsers should ignore all unrecognised optional fields. Currently the
possible optional fields are:
2020-02-17 19:12:18 +03:00
================ ==============================================================
shared:X mount is shared in peer group X
master:X mount is slave to peer group X
propagate_from:X mount is slave and receives propagation from peer group X [#]_
unbindable mount is unbindable
================ ==============================================================
2008-03-27 15:06:25 +03:00
2020-02-17 19:12:18 +03:00
.. [#] X is the closest dominant peer group under the process's root. If
X is the immediate master of the mount, or if there's no dominant peer
group under the same root, then only the "master:X" field is present
and not the "propagate_from:X" field.
2008-03-27 15:06:26 +03:00
2008-03-27 15:06:25 +03:00
For more information on mount propagation see:
Documentation/filesystems/sharedsubtree.txt
2009-12-15 05:00:05 +03:00
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
--------------------------------------------------------
These files provide a method to access a tasks comm value. It also allows for
a task to set its own or one of its thread siblings comm value. The comm value
is limited in size compared to the cmdline value, so writing anything longer
then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
comm value.
procfs: add hidepid= and gid= mount options
Add support for mount options to restrict access to /proc/PID/
directories. The default backward-compatible "relaxed" behaviour is left
untouched.
The first mount option is called "hidepid" and its value defines how much
info about processes we want to be available for non-owners:
hidepid=0 (default) means the old behavior - anybody may read all
world-readable /proc/PID/* files.
hidepid=1 means users may not access any /proc/<pid>/ directories, but
their own. Sensitive files like cmdline, sched*, status are now protected
against other users. As permission checking done in proc_pid_permission()
and files' permissions are left untouched, programs expecting specific
files' modes are not confused.
hidepid=2 means hidepid=1 plus all /proc/PID/ will be invisible to other
users. It doesn't mean that it hides whether a process exists (it can be
learned by other means, e.g. by kill -0 $PID), but it hides process' euid
and egid. It compicates intruder's task of gathering info about running
processes, whether some daemon runs with elevated privileges, whether
another user runs some sensitive program, whether other users run any
program at all, etc.
gid=XXX defines a group that will be able to gather all processes' info
(as in hidepid=0 mode). This group should be used instead of putting
nonroot user in sudoers file or something. However, untrusted users (like
daemons, etc.) which are not supposed to monitor the tasks in the whole
system should not be added to the group.
hidepid=1 or higher is designed to restrict access to procfs files, which
might reveal some sensitive private information like precise keystrokes
timings:
http://www.openwall.com/lists/oss-security/2011/11/05/3
hidepid=1/2 doesn't break monitoring userspace tools. ps, top, pgrep, and
conky gracefully handle EPERM/ENOENT and behave as if the current user is
the only user running processes. pstree shows the process subtree which
contains "pstree" process.
Note: the patch doesn't deal with setuid/setgid issues of keeping
preopened descriptors of procfs files (like
https://lkml.org/lkml/2011/2/7/368). We rely on that the leaked
information like the scheduling counters of setuid apps doesn't threaten
anybody's privacy - only the user started the setuid program may read the
counters.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg KH <greg@kroah.com>
Cc: Theodore Tso <tytso@MIT.EDU>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: James Morris <jmorris@namei.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-11 03:11:31 +04:00
2012-06-01 03:26:43 +04:00
3.7 /proc/<pid>/task/<tid>/children - Information about task children
-------------------------------------------------------------------------
This file provides a fast way to retrieve first level children pids
of a task pointed by <pid>/<tid> pair. The format is a space separated
stream of pids.
Note the "first level" here -- if a child has own children they will
not be listed here, one needs to read /proc/<children-pid>/task/<tid>/children
to obtain the descendants.
Since this interface is intended to be fast and cheap it doesn't
guarantee to provide precise results and some children might be
skipped, especially if they've exited right after we printed their
pids, so one need to either stop or freeze processes being inspected
if precise results are needed.
2014-04-08 02:38:34 +04:00
3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
2012-12-18 04:05:14 +04:00
---------------------------------------------------------------
This file provides information associated with an opened file. The regular
2014-04-08 02:38:34 +04:00
files have at least three fields -- 'pos', 'flags' and mnt_id. The 'pos'
represents the current offset of the opened file in decimal form [see lseek(2)
for details], 'flags' denotes the octal O_xxx mask the file has been
created with [see open(2) for details] and 'mnt_id' represents mount ID of
the file system containing the opened file [see 3.5 /proc/<pid>/mountinfo
for details].
2012-12-18 04:05:14 +04:00
2020-02-17 19:12:18 +03:00
A typical output is::
2012-12-18 04:05:14 +04:00
pos: 0
flags: 0100002
2014-04-08 02:38:34 +04:00
mnt_id: 19
2012-12-18 04:05:14 +04:00
2020-02-17 19:12:18 +03:00
All locks associated with a file descriptor are shown in its fdinfo too::
2015-04-16 22:49:38 +03:00
2020-02-17 19:12:18 +03:00
lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF
2015-04-16 22:49:38 +03:00
2012-12-18 04:05:14 +04:00
The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags
pair provide additional information particular to the objects they represent.
2020-02-17 19:12:18 +03:00
Eventfd files
~~~~~~~~~~~~~
::
2012-12-18 04:05:14 +04:00
pos: 0
flags: 04002
2014-04-08 02:38:34 +04:00
mnt_id: 9
2012-12-18 04:05:14 +04:00
eventfd-count: 5a
2020-02-17 19:12:18 +03:00
where 'eventfd-count' is hex value of a counter.
Signalfd files
~~~~~~~~~~~~~~
::
2012-12-18 04:05:14 +04:00
pos: 0
flags: 04002
2014-04-08 02:38:34 +04:00
mnt_id: 9
2012-12-18 04:05:14 +04:00
sigmask: 0000000000000200
2020-02-17 19:12:18 +03:00
where 'sigmask' is hex value of the signal mask associated
with a file.
Epoll files
~~~~~~~~~~~
::
2012-12-18 04:05:14 +04:00
pos: 0
flags: 02
2014-04-08 02:38:34 +04:00
mnt_id: 9
2017-07-13 00:34:25 +03:00
tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7
2012-12-18 04:05:14 +04:00
2020-02-17 19:12:18 +03:00
where 'tfd' is a target file descriptor number in decimal form,
'events' is events mask being watched and the 'data' is data
associated with a target [see epoll(7) for more details].
2012-12-18 04:05:14 +04:00
2020-02-17 19:12:18 +03:00
The 'pos' is current offset of the target file in decimal form
[see lseek(2)], 'ino' and 'sdev' are inode and device numbers
where target file resides, all in hex format.
2017-07-13 00:34:25 +03:00
2020-02-17 19:12:18 +03:00
Fsnotify files
~~~~~~~~~~~~~~
For inotify files the format is the following::
2012-12-18 04:05:14 +04:00
pos: 0
flags: 02000000
inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d
2020-02-17 19:12:18 +03:00
where 'wd' is a watch descriptor in decimal form, ie a target file
descriptor number, 'ino' and 'sdev' are inode and device where the
target file resides and the 'mask' is the mask of events, all in hex
form [see inotify(7) for more details].
2012-12-18 04:05:14 +04:00
2020-02-17 19:12:18 +03:00
If the kernel was built with exportfs support, the path to the target
file is encoded as a file handle. The file handle is provided by three
fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex
format.
2012-12-18 04:05:14 +04:00
2020-02-17 19:12:18 +03:00
If the kernel is built without exportfs support the file handle won't be
printed out.
2012-12-18 04:05:14 +04:00
2020-02-17 19:12:18 +03:00
If there is no inotify mark attached yet the 'inotify' line will be omitted.
2012-12-18 04:05:14 +04:00
2020-02-17 19:12:18 +03:00
For fanotify files the format is::
2012-12-18 04:05:14 +04:00
pos: 0
flags: 02
2014-04-08 02:38:34 +04:00
mnt_id: 9
2012-12-18 04:05:18 +04:00
fanotify flags:10 event-flags:0
fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003
fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4
2020-02-17 19:12:18 +03:00
where fanotify 'flags' and 'event-flags' are values used in fanotify_init
call, 'mnt_id' is the mount point identifier, 'mflags' is the value of
flags associated with mark which are tracked separately from events
mask. 'ino', 'sdev' are target inode and device, 'mask' is the events
mask and 'ignored_mask' is the mask of events which are to be ignored.
All in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask'
does provide information about flags and mask used in fanotify_mark
call [see fsnotify manpage for details].
While the first three lines are mandatory and always printed, the rest is
optional and may be omitted if no marks created yet.
2012-12-18 04:05:18 +04:00
2020-02-17 19:12:18 +03:00
Timerfd files
~~~~~~~~~~~~~
2012-12-18 04:05:14 +04:00
2020-02-17 19:12:18 +03:00
::
2014-07-16 01:54:53 +04:00
pos: 0
flags: 02
mnt_id: 9
clockid: 0
ticks: 0
settime flags: 01
it_value: (0, 49406829)
it_interval: (1, 0)
2020-02-17 19:12:18 +03:00
where 'clockid' is the clock type and 'ticks' is the number of the timer expirations
that have occurred [see timerfd_create(2) for details]. 'settime flags' are
flags in octal form been used to setup the timer [see timerfd_settime(2) for
details]. 'it_value' is remaining time until the timer exiration.
'it_interval' is the interval for the timer. Note the timer might be set up
with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value'
still exhibits timer's remaining time.
2012-12-18 04:05:14 +04:00
2015-02-12 02:28:31 +03:00
3.9 /proc/<pid>/map_files - Information about memory mapped files
---------------------------------------------------------------------
This directory contains symbolic links which represent memory mapped files
2020-02-17 19:12:18 +03:00
the process is maintaining. Example output::
2015-02-12 02:28:31 +03:00
| lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so
| lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so
| lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so
| ...
| lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1
| lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls
The name of a link represents the virtual memory bounds of a mapping, i.e.
vm_area_struct::vm_start-vm_area_struct::vm_end.
The main purpose of the map_files is to retrieve a set of memory mapped
files in a fast way instead of parsing /proc/<pid>/maps or
/proc/<pid>/smaps, both of which contain many more records. At the same
time one can open(2) mappings from the listings of two processes and
comparing their inode numbers to figure out which anonymous memory areas
are actually shared.
2016-03-18 00:20:54 +03:00
3.10 /proc/<pid>/timerslack_ns - Task timerslack value
---------------------------------------------------------
This file provides the value of the task's timerslack value in nanoseconds.
This value specifies a amount of time that normal timers may be deferred
in order to coalesce timers and avoid unnecessary wakeups.
This allows a task's interactivity vs power consumption trade off to be
adjusted.
Writing 0 to the file will set the tasks timerslack to the default value.
Valid values are from 0 - ULLONG_MAX
An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS level
permissions on the task specified to change its timerslack_ns value.
2017-02-14 04:42:41 +03:00
3.11 /proc/<pid>/patch_state - Livepatch patch operation state
-----------------------------------------------------------------
When CONFIG_LIVEPATCH is enabled, this file displays the value of the
patch state for the task.
A value of '-1' indicates that no patch is in transition.
A value of '0' indicates that a patch is in transition and the task is
unpatched. If the patch is being enabled, then the task hasn't been
patched yet. If the patch is being disabled, then the task has already
been unpatched.
A value of '1' indicates that a patch is in transition and the task is
patched. If the patch is being enabled, then the task has already been
patched. If the patch is being disabled, then the task hasn't been
unpatched yet.
2019-06-06 04:22:36 +03:00
3.12 /proc/<pid>/arch_status - task architecture specific status
-------------------------------------------------------------------
When CONFIG_PROC_PID_ARCH_STATUS is enabled, this file displays the
architecture specific status of the task.
Example
2020-02-17 19:12:18 +03:00
~~~~~~~
::
2019-06-06 04:22:36 +03:00
$ cat /proc/6753/arch_status
AVX512_elapsed_ms: 8
Description
2020-02-17 19:12:18 +03:00
~~~~~~~~~~~
2019-06-06 04:22:36 +03:00
x86 specific entries:
2020-02-17 19:12:18 +03:00
~~~~~~~~~~~~~~~~~~~~~
AVX512_elapsed_ms:
^^^^^^^^^^^^^^^^^^
2019-06-06 04:22:36 +03:00
If AVX512 is supported on the machine, this entry shows the milliseconds
elapsed since the last time AVX512 usage was recorded. The recording
happens on a best effort basis when a task is scheduled out. This means
that the value depends on two factors:
1) The time which the task spent on the CPU without being scheduled
out. With CPU isolation and a single runnable task this can take
several seconds.
2) The time since the task was scheduled out last. Depending on the
reason for being scheduled out (time slice exhausted, syscall ...)
this can be arbitrary long time.
As a consequence the value cannot be considered precise and authoritative
information. The application which uses this information has to be aware
of the overall scenario on the system in order to determine whether a
task is a real AVX512 user or not. Precise information can be obtained
with performance counters.
A special value of '-1' indicates that no AVX512 usage was recorded, thus
the task is unlikely an AVX512 user, but depends on the workload and the
scheduling scenario, it also could be a false negative mentioned above.
2016-03-18 00:20:54 +03:00
procfs: add hidepid= and gid= mount options
Add support for mount options to restrict access to /proc/PID/
directories. The default backward-compatible "relaxed" behaviour is left
untouched.
The first mount option is called "hidepid" and its value defines how much
info about processes we want to be available for non-owners:
hidepid=0 (default) means the old behavior - anybody may read all
world-readable /proc/PID/* files.
hidepid=1 means users may not access any /proc/<pid>/ directories, but
their own. Sensitive files like cmdline, sched*, status are now protected
against other users. As permission checking done in proc_pid_permission()
and files' permissions are left untouched, programs expecting specific
files' modes are not confused.
hidepid=2 means hidepid=1 plus all /proc/PID/ will be invisible to other
users. It doesn't mean that it hides whether a process exists (it can be
learned by other means, e.g. by kill -0 $PID), but it hides process' euid
and egid. It compicates intruder's task of gathering info about running
processes, whether some daemon runs with elevated privileges, whether
another user runs some sensitive program, whether other users run any
program at all, etc.
gid=XXX defines a group that will be able to gather all processes' info
(as in hidepid=0 mode). This group should be used instead of putting
nonroot user in sudoers file or something. However, untrusted users (like
daemons, etc.) which are not supposed to monitor the tasks in the whole
system should not be added to the group.
hidepid=1 or higher is designed to restrict access to procfs files, which
might reveal some sensitive private information like precise keystrokes
timings:
http://www.openwall.com/lists/oss-security/2011/11/05/3
hidepid=1/2 doesn't break monitoring userspace tools. ps, top, pgrep, and
conky gracefully handle EPERM/ENOENT and behave as if the current user is
the only user running processes. pstree shows the process subtree which
contains "pstree" process.
Note: the patch doesn't deal with setuid/setgid issues of keeping
preopened descriptors of procfs files (like
https://lkml.org/lkml/2011/2/7/368). We rely on that the leaked
information like the scheduling counters of setuid apps doesn't threaten
anybody's privacy - only the user started the setuid program may read the
counters.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg KH <greg@kroah.com>
Cc: Theodore Tso <tytso@MIT.EDU>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: James Morris <jmorris@namei.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-11 03:11:31 +04:00
Configuring procfs
2020-02-17 19:12:18 +03:00
------------------
procfs: add hidepid= and gid= mount options
Add support for mount options to restrict access to /proc/PID/
directories. The default backward-compatible "relaxed" behaviour is left
untouched.
The first mount option is called "hidepid" and its value defines how much
info about processes we want to be available for non-owners:
hidepid=0 (default) means the old behavior - anybody may read all
world-readable /proc/PID/* files.
hidepid=1 means users may not access any /proc/<pid>/ directories, but
their own. Sensitive files like cmdline, sched*, status are now protected
against other users. As permission checking done in proc_pid_permission()
and files' permissions are left untouched, programs expecting specific
files' modes are not confused.
hidepid=2 means hidepid=1 plus all /proc/PID/ will be invisible to other
users. It doesn't mean that it hides whether a process exists (it can be
learned by other means, e.g. by kill -0 $PID), but it hides process' euid
and egid. It compicates intruder's task of gathering info about running
processes, whether some daemon runs with elevated privileges, whether
another user runs some sensitive program, whether other users run any
program at all, etc.
gid=XXX defines a group that will be able to gather all processes' info
(as in hidepid=0 mode). This group should be used instead of putting
nonroot user in sudoers file or something. However, untrusted users (like
daemons, etc.) which are not supposed to monitor the tasks in the whole
system should not be added to the group.
hidepid=1 or higher is designed to restrict access to procfs files, which
might reveal some sensitive private information like precise keystrokes
timings:
http://www.openwall.com/lists/oss-security/2011/11/05/3
hidepid=1/2 doesn't break monitoring userspace tools. ps, top, pgrep, and
conky gracefully handle EPERM/ENOENT and behave as if the current user is
the only user running processes. pstree shows the process subtree which
contains "pstree" process.
Note: the patch doesn't deal with setuid/setgid issues of keeping
preopened descriptors of procfs files (like
https://lkml.org/lkml/2011/2/7/368). We rely on that the leaked
information like the scheduling counters of setuid apps doesn't threaten
anybody's privacy - only the user started the setuid program may read the
counters.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg KH <greg@kroah.com>
Cc: Theodore Tso <tytso@MIT.EDU>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: James Morris <jmorris@namei.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-11 03:11:31 +04:00
4.1 Mount options
---------------------
The following mount options are supported:
2020-02-17 19:12:18 +03:00
========= ========================================================
procfs: add hidepid= and gid= mount options
Add support for mount options to restrict access to /proc/PID/
directories. The default backward-compatible "relaxed" behaviour is left
untouched.
The first mount option is called "hidepid" and its value defines how much
info about processes we want to be available for non-owners:
hidepid=0 (default) means the old behavior - anybody may read all
world-readable /proc/PID/* files.
hidepid=1 means users may not access any /proc/<pid>/ directories, but
their own. Sensitive files like cmdline, sched*, status are now protected
against other users. As permission checking done in proc_pid_permission()
and files' permissions are left untouched, programs expecting specific
files' modes are not confused.
hidepid=2 means hidepid=1 plus all /proc/PID/ will be invisible to other
users. It doesn't mean that it hides whether a process exists (it can be
learned by other means, e.g. by kill -0 $PID), but it hides process' euid
and egid. It compicates intruder's task of gathering info about running
processes, whether some daemon runs with elevated privileges, whether
another user runs some sensitive program, whether other users run any
program at all, etc.
gid=XXX defines a group that will be able to gather all processes' info
(as in hidepid=0 mode). This group should be used instead of putting
nonroot user in sudoers file or something. However, untrusted users (like
daemons, etc.) which are not supposed to monitor the tasks in the whole
system should not be added to the group.
hidepid=1 or higher is designed to restrict access to procfs files, which
might reveal some sensitive private information like precise keystrokes
timings:
http://www.openwall.com/lists/oss-security/2011/11/05/3
hidepid=1/2 doesn't break monitoring userspace tools. ps, top, pgrep, and
conky gracefully handle EPERM/ENOENT and behave as if the current user is
the only user running processes. pstree shows the process subtree which
contains "pstree" process.
Note: the patch doesn't deal with setuid/setgid issues of keeping
preopened descriptors of procfs files (like
https://lkml.org/lkml/2011/2/7/368). We rely on that the leaked
information like the scheduling counters of setuid apps doesn't threaten
anybody's privacy - only the user started the setuid program may read the
counters.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg KH <greg@kroah.com>
Cc: Theodore Tso <tytso@MIT.EDU>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: James Morris <jmorris@namei.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-11 03:11:31 +04:00
hidepid= Set /proc/<pid>/ access mode.
gid= Set the group authorized to learn processes information.
2020-02-17 19:12:18 +03:00
========= ========================================================
procfs: add hidepid= and gid= mount options
Add support for mount options to restrict access to /proc/PID/
directories. The default backward-compatible "relaxed" behaviour is left
untouched.
The first mount option is called "hidepid" and its value defines how much
info about processes we want to be available for non-owners:
hidepid=0 (default) means the old behavior - anybody may read all
world-readable /proc/PID/* files.
hidepid=1 means users may not access any /proc/<pid>/ directories, but
their own. Sensitive files like cmdline, sched*, status are now protected
against other users. As permission checking done in proc_pid_permission()
and files' permissions are left untouched, programs expecting specific
files' modes are not confused.
hidepid=2 means hidepid=1 plus all /proc/PID/ will be invisible to other
users. It doesn't mean that it hides whether a process exists (it can be
learned by other means, e.g. by kill -0 $PID), but it hides process' euid
and egid. It compicates intruder's task of gathering info about running
processes, whether some daemon runs with elevated privileges, whether
another user runs some sensitive program, whether other users run any
program at all, etc.
gid=XXX defines a group that will be able to gather all processes' info
(as in hidepid=0 mode). This group should be used instead of putting
nonroot user in sudoers file or something. However, untrusted users (like
daemons, etc.) which are not supposed to monitor the tasks in the whole
system should not be added to the group.
hidepid=1 or higher is designed to restrict access to procfs files, which
might reveal some sensitive private information like precise keystrokes
timings:
http://www.openwall.com/lists/oss-security/2011/11/05/3
hidepid=1/2 doesn't break monitoring userspace tools. ps, top, pgrep, and
conky gracefully handle EPERM/ENOENT and behave as if the current user is
the only user running processes. pstree shows the process subtree which
contains "pstree" process.
Note: the patch doesn't deal with setuid/setgid issues of keeping
preopened descriptors of procfs files (like
https://lkml.org/lkml/2011/2/7/368). We rely on that the leaked
information like the scheduling counters of setuid apps doesn't threaten
anybody's privacy - only the user started the setuid program may read the
counters.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg KH <greg@kroah.com>
Cc: Theodore Tso <tytso@MIT.EDU>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: James Morris <jmorris@namei.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-11 03:11:31 +04:00
hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories
(default).
hidepid=1 means users may not access any /proc/<pid>/ directories but their
own. Sensitive files like cmdline, sched*, status are now protected against
other users. This makes it impossible to learn whether any user runs
specific program (given the program doesn't reveal itself by its behaviour).
As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users,
poorly written programs passing sensitive information via program arguments are
now protected against local eavesdroppers.
hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other
users. It doesn't mean that it hides a fact whether a process with a specific
pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"),
but it hides process' uid and gid, which may be learned by stat()'ing
/proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering
information about running processes, whether some daemon runs with elevated
privileges, whether other user runs some sensitive program, whether other users
run any program at all, etc.
gid= defines a group authorized to learn processes information otherwise
prohibited by hidepid=. If you use some daemon like identd which needs to learn
information about processes information, just add identd to this group.
