Commit Graph

50 Commits

Author SHA1 Message Date
Linus Torvalds
233a806b00 This was a reasonably active cycle for documentation; this pull includes:
- Some kernel-doc cleanups.  That script is still regex onslaught from
    hell, but it has gotten a little better.
 
  - Improvements to the checkpatch docs, which are also used by the tool
    itself.
 
  - A major update to the pathname lookup documentation.
 
  - Elimination of :doc: markup, since our automarkup magic can create
    references from filenames without all the extra noise.
 
  - The flurry of Chinese translation activity continues.
 
 Plus, of course, the usual collection of updates, typo fixes, and warning
 fixes.
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Merge tag 'docs-5.14' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "This was a reasonably active cycle for documentation; this includes:

   - Some kernel-doc cleanups. That script is still regex onslaught from
     hell, but it has gotten a little better.

   - Improvements to the checkpatch docs, which are also used by the
     tool itself.

   - A major update to the pathname lookup documentation.

   - Elimination of :doc: markup, since our automarkup magic can create
     references from filenames without all the extra noise.

   - The flurry of Chinese translation activity continues.

  Plus, of course, the usual collection of updates, typo fixes, and
  warning fixes"

* tag 'docs-5.14' of git://git.lwn.net/linux: (115 commits)
  docs: path-lookup: use bare function() rather than literals
  docs: path-lookup: update symlink description
  docs: path-lookup: update get_link() ->follow_link description
  docs: path-lookup: update WALK_GET, WALK_PUT desc
  docs: path-lookup: no get_link()
  docs: path-lookup: update i_op->put_link and cookie description
  docs: path-lookup: i_op->follow_link replaced with i_op->get_link
  docs: path-lookup: Add macro name to symlink limit description
  docs: path-lookup: remove filename_mountpoint
  docs: path-lookup: update do_last() part
  docs: path-lookup: update path_mountpoint() part
  docs: path-lookup: update path_to_nameidata() part
  docs: path-lookup: update follow_managed() part
  docs: Makefile: Use CONFIG_SHELL not SHELL
  docs: Take a little noise out of the build process
  docs: x86: avoid using ReST :doc:`foo` markup
  docs: virt: kvm: s390-pv-boot.rst: avoid using ReST :doc:`foo` markup
  docs: userspace-api: landlock.rst: avoid using ReST :doc:`foo` markup
  docs: trace: ftrace.rst: avoid using ReST :doc:`foo` markup
  docs: trace: coresight: coresight.rst: avoid using ReST :doc:`foo` markup
  ...
2021-06-28 16:53:05 -07:00
Mauro Carvalho Chehab
2793e19d63 docs: admin-guide: sysctl: avoid using ReST :doc:foo markup
The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/12abd2290c7ebc05c89178d2556bea740bd70fac.1623824363.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-06-17 13:24:36 -06:00
Ingo Molnar
a9e906b71f Merge branch 'sched/urgent' into sched/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2021-06-03 19:00:49 +02:00
Linus Torvalds
d7c5303fbc Networking fixes for 5.13-rc4, including fixes from bpf, netfilter,
can and wireless trees. Notably including fixes for the recently
 announced "FragAttacks" WiFi vulnerabilities. Rather large batch,
 touching some core parts of the stack, too, but nothing hair-raising.
 
 Current release - regressions:
 
  - tipc: make node link identity publish thread safe
 
  - dsa: felix: re-enable TAS guard band mode
 
  - stmmac: correct clocks enabled in stmmac_vlan_rx_kill_vid()
 
  - stmmac: fix system hang if change mac address after interface ifdown
 
 Current release - new code bugs:
 
  - mptcp: avoid OOB access in setsockopt()
 
  - bpf: Fix nested bpf_bprintf_prepare with more per-cpu buffers
 
  - ethtool: stats: fix a copy-paste error - init correct array size
 
 Previous releases - regressions:
 
  - sched: fix packet stuck problem for lockless qdisc
 
  - net: really orphan skbs tied to closing sk
 
  - mlx4: fix EEPROM dump support
 
  - bpf: fix alu32 const subreg bound tracking on bitwise operations
 
  - bpf: fix mask direction swap upon off reg sign change
 
  - bpf, offload: reorder offload callback 'prepare' in verifier
 
  - stmmac: Fix MAC WoL not working if PHY does not support WoL
 
  - packetmmap: fix only tx timestamp on request
 
  - tipc: skb_linearize the head skb when reassembling msgs
 
 Previous releases - always broken:
 
  - mac80211: address recent "FragAttacks" vulnerabilities
 
  - mac80211: do not accept/forward invalid EAPOL frames
 
  - mptcp: avoid potential error message floods
 
  - bpf, ringbuf: deny reserve of buffers larger than ringbuf to prevent
                  out of buffer writes
 
  - bpf: forbid trampoline attach for functions with variable arguments
 
  - bpf: add deny list of functions to prevent inf recursion of tracing
         programs
 
  - tls splice: check SPLICE_F_NONBLOCK instead of MSG_DONTWAIT
 
  - can: isotp: prevent race between isotp_bind() and isotp_setsockopt()
 
  - netfilter: nft_set_pipapo_avx2: Add irq_fpu_usable() check,
               fallback to non-AVX2 version
 
 Misc:
 
  - bpf: add kconfig knob for disabling unpriv bpf by default
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Merge tag 'net-5.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Pull networking fixes from Jakub Kicinski:
 "Networking fixes for 5.13-rc4, including fixes from bpf, netfilter,
  can and wireless trees. Notably including fixes for the recently
  announced "FragAttacks" WiFi vulnerabilities. Rather large batch,
  touching some core parts of the stack, too, but nothing hair-raising.

  Current release - regressions:

   - tipc: make node link identity publish thread safe

   - dsa: felix: re-enable TAS guard band mode

   - stmmac: correct clocks enabled in stmmac_vlan_rx_kill_vid()

   - stmmac: fix system hang if change mac address after interface
     ifdown

  Current release - new code bugs:

   - mptcp: avoid OOB access in setsockopt()

   - bpf: Fix nested bpf_bprintf_prepare with more per-cpu buffers

   - ethtool: stats: fix a copy-paste error - init correct array size

  Previous releases - regressions:

   - sched: fix packet stuck problem for lockless qdisc

   - net: really orphan skbs tied to closing sk

   - mlx4: fix EEPROM dump support

   - bpf: fix alu32 const subreg bound tracking on bitwise operations

   - bpf: fix mask direction swap upon off reg sign change

   - bpf, offload: reorder offload callback 'prepare' in verifier

   - stmmac: Fix MAC WoL not working if PHY does not support WoL

   - packetmmap: fix only tx timestamp on request

   - tipc: skb_linearize the head skb when reassembling msgs

  Previous releases - always broken:

   - mac80211: address recent "FragAttacks" vulnerabilities

   - mac80211: do not accept/forward invalid EAPOL frames

   - mptcp: avoid potential error message floods

   - bpf, ringbuf: deny reserve of buffers larger than ringbuf to
     prevent out of buffer writes

   - bpf: forbid trampoline attach for functions with variable arguments

   - bpf: add deny list of functions to prevent inf recursion of tracing
     programs

   - tls splice: check SPLICE_F_NONBLOCK instead of MSG_DONTWAIT

   - can: isotp: prevent race between isotp_bind() and
     isotp_setsockopt()

   - netfilter: nft_set_pipapo_avx2: Add irq_fpu_usable() check,
     fallback to non-AVX2 version

  Misc:

   - bpf: add kconfig knob for disabling unpriv bpf by default"

* tag 'net-5.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (172 commits)
  net: phy: Document phydev::dev_flags bits allocation
  mptcp: validate 'id' when stopping the ADD_ADDR retransmit timer
  mptcp: avoid error message on infinite mapping
  mptcp: drop unconditional pr_warn on bad opt
  mptcp: avoid OOB access in setsockopt()
  nfp: update maintainer and mailing list addresses
  net: mvpp2: add buffer header handling in RX
  bnx2x: Fix missing error code in bnx2x_iov_init_one()
  net: zero-initialize tc skb extension on allocation
  net: hns: Fix kernel-doc
  sctp: fix the proc_handler for sysctl encap_port
  sctp: add the missing setting for asoc encap_port
  bpf, selftests: Adjust few selftest result_unpriv outcomes
  bpf: No need to simulate speculative domain for immediates
  bpf: Fix mask direction swap upon off reg sign change
  bpf: Wrap aux data inside bpf_sanitize_info container
  bpf: Fix BPF_LSM kconfig symbol dependency
  selftests/bpf: Add test for l3 use of bpf_redirect_peer
  bpftool: Add sock_release help info for cgroup attach/prog load command
  net: dsa: microchip: enable phy errata workaround on 9567
  ...
2021-05-26 17:44:49 -10:00
Mel Gorman
fcb5017045 delayacct: Document task_delayacct sysctl
Update sysctl/kernel.rst.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210512114035.GH3672@suse.de
2021-05-18 12:53:53 +02:00
Rasmus Villemoes
f4d3f25ace docs: admin-guide: update description for kernel.modprobe sysctl
When I added CONFIG_MODPROBE_PATH, I neglected to update Documentation/.
It's still true that this defaults to /sbin/modprobe, but now via a level
of indirection.  So document that the kernel might have been built with
something other than /sbin/modprobe as the initial value.

Link: https://lkml.kernel.org/r/20210420125324.1246826-1-linux@rasmusvillemoes.dk
Fixes: 17652f4240 ("modules: add CONFIG_MODPROBE_PATH")
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-14 19:41:32 -07:00
Rasmus Villemoes
1e886090ce docs: admin-guide: update description for kernel.hotplug sysctl
It's been a few releases since this defaulted to /sbin/hotplug. Update
the text, and include pointers to the two CONFIG_UEVENT_HELPER{,_PATH}
config knobs whose help text could provide more info, but also hint
that the user probably doesn't need to care at all.

Fixes: 7934779a69 ("Driver-Core: disable /sbin/hotplug by default")
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20210420120638.1104016-1-linux@rasmusvillemoes.dk
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-05-13 10:14:17 -06:00
Daniel Borkmann
08389d8882 bpf: Add kconfig knob for disabling unpriv bpf by default
Add a kconfig knob which allows for unprivileged bpf to be disabled by default.
If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2.

This still allows a transition of 2 -> {0,1} through an admin. Similarly,
this also still keeps 1 -> {1} behavior intact, so that once set to permanently
disabled, it cannot be undone aside from a reboot.

We've also added extra2 with max of 2 for the procfs handler, so that an admin
still has a chance to toggle between 0 <-> 2.

Either way, as an additional alternative, applications can make use of CAP_BPF
that we added a while ago.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net
2021-05-11 13:56:16 -07:00
Mathieu Chouquet-Stringer
547f574fd9 docs: Update documentation to reflect what TAINT_CPU_OUT_OF_SPEC means
Here's a patch updating the meaning of TAINT_CPU_OUT_OF_SPEC after
Borislav introduced changes in a7e1f67ed2 and upcoming patches in tip.

TAINT_CPU_OUT_OF_SPEC now means a bit more what it implies as the
flag isn't set just because of a CPU misconfiguration or mismatch.
Historically it was for SMP kernel oops on an officially SMP incapable
processor but now it also covers CPUs whose MSRs have been incorrectly
poked at from userspace, drivers being used on non supported
architectures, broken firmware, mismatched CPUs, ...

Update documentation and script to reflect that.

Signed-off-by: Mathieu Chouquet-Stringer <me@mathieu.digital>
Link: https://lore.kernel.org/r/20201202153244.709752-1-me@mathieu.digital
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-12-08 10:53:58 -07:00
Andrew Klychkov
751d5b2741 Documentation: fix multiple typos found in the admin-guide subdirectory
Fix thirty five typos in dm-integrity.rst, dm-raid.rst, dm-zoned.rst,
verity.rst, writecache.rst, tsx_async_abort.rst, md.rst, bttv.rst,
dvb_references.rst, frontend-cardlist.rst, gspca-cardlist.rst, ipu3.rst,
remote-controller.rst, mm/index.rst, numaperf.rst, userfaultfd.rst,
module-signing.rst, imx-ddr.rst, intel-speed-select.rst,
intel_pstate.rst, ramoops.rst, abi.rst, kernel.rst, vm.rst

Signed-off-by: Andrew Klychkov <andrew.a.klychkov@gmail.com>
Link: https://lore.kernel.org/r/20201204072848.GA49895@spblnx124.lan
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-12-08 10:27:56 -07:00
Stephen Kitt
d151a23d7b docs: clean up sysctl/kernel: titles, version
This cleans up a few titles with extra colons, and removes the
reference to kernel 2.2. The docs don't yet cover *all* of 5.10 or
5.11, but I think they're close enough. Most entries are documented,
and have been checked against current kernels.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20201208074922.30359-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-12-08 10:22:21 -07:00
Lepton Wu
f38c85f1ba coredump: add %f for executable filename
The document reads "%e" should be "executable filename" while actually it
could be changed by things like pr_ctl PR_SET_NAME.  People who uses "%e"
in core_pattern get surprised when they find out they get thread name
instead of executable filename.

This is either a bug of document or a bug of code.  Since the behavior of
"%e" is there for long time, it could bring another surprise for users if
we "fix" the code.

So we just "fix" the document.  And more, for users who really need the
"executable filename" in core_pattern, we introduce a new "%f" for the
real executable filename.  We already have "%E" for executable path in
kernel, so just reuse most of its code for the new added "%f" format.

Signed-off-by: Lepton Wu <ytht.net@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200701031432.2978761-1-ytht.net@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 10:58:01 -07:00
Linus Torvalds
2324d50d05 It's been a busy cycle for documentation - hopefully the busiest for a
while to come.  Changes include:
 
  - Some new Chinese translations
 
  - Progress on the battle against double words words and non-HTTPS URLs
 
  - Some block-mq documentation
 
  - More RST conversions from Mauro.  At this point, that task is
    essentially complete, so we shouldn't see this kind of churn again for a
    while.  Unless we decide to switch to asciidoc or something...:)
 
  - Lots of typo fixes, warning fixes, and more.
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Merge tag 'docs-5.9' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "It's been a busy cycle for documentation - hopefully the busiest for a
  while to come. Changes include:

   - Some new Chinese translations

   - Progress on the battle against double words words and non-HTTPS
     URLs

   - Some block-mq documentation

   - More RST conversions from Mauro. At this point, that task is
     essentially complete, so we shouldn't see this kind of churn again
     for a while. Unless we decide to switch to asciidoc or
     something...:)

   - Lots of typo fixes, warning fixes, and more"

* tag 'docs-5.9' of git://git.lwn.net/linux: (195 commits)
  scripts/kernel-doc: optionally treat warnings as errors
  docs: ia64: correct typo
  mailmap: add entry for <alobakin@marvell.com>
  doc/zh_CN: add cpu-load Chinese version
  Documentation/admin-guide: tainted-kernels: fix spelling mistake
  MAINTAINERS: adjust kprobes.rst entry to new location
  devices.txt: document rfkill allocation
  PCI: correct flag name
  docs: filesystems: vfs: correct flag name
  docs: filesystems: vfs: correct sync_mode flag names
  docs: path-lookup: markup fixes for emphasis
  docs: path-lookup: more markup fixes
  docs: path-lookup: fix HTML entity mojibake
  CREDITS: Replace HTTP links with HTTPS ones
  docs: process: Add an example for creating a fixes tag
  doc/zh_CN: add Chinese translation prefer section
  doc/zh_CN: add clearing-warn-once Chinese version
  doc/zh_CN: add admin-guide index
  doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label
  futex: MAINTAINERS: Re-add selftests directory
  ...
2020-08-04 22:47:54 -07:00
Qais Yousef
1f73d1abe5 Documentation/sysctl: Document uclamp sysctl knobs
Uclamp exposes 3 sysctl knobs:

	* sched_util_clamp_min
	* sched_util_clamp_max
	* sched_util_clamp_min_rt_default

Document them in sysctl/kernel.rst.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200716110347.19553-3-qais.yousef@arm.com
2020-07-29 13:51:48 +02:00
Randy Dunlap
ee74db082a Documentation/admin-guide: sysctl/kernel: drop doubled word
Drop the doubled word "set".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Link: https://lore.kernel.org/r/20200704032020.21923-12-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-05 14:01:49 -06:00
Stephen Kitt
0b227076d5 docs: sysctl/kernel: document random
This documents the random directory, based on the behaviour seen in
drivers/char/random.c.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200623112514.10650-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-06-26 11:25:14 -06:00
Randy Dunlap
e996919b72 Documentation: fix sysctl/kernel.rst heading format warnings
Fix heading format warnings in admin-guide/sysctl/kernel.rst:

Documentation/admin-guide/sysctl/kernel.rst:339: WARNING: Title underline too short.
hung_task_all_cpu_backtrace:
================

Documentation/admin-guide/sysctl/kernel.rst:650: WARNING: Title underline too short.
oops_all_cpu_backtrace:
================

Fixes: 0ec9dc9bcb ("kernel/hung_task.c: introduce sysctl to print all traces when a hung task is detected")
Fixes: 60c958d8df ("panic: add sysctl to dump all CPUs backtraces on oops event")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/8af1cb77-4b5a-64b9-da5d-f6a95e537f99@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-06-19 13:24:57 -06:00
Guilherme G. Piccoli
60c958d8df panic: add sysctl to dump all CPUs backtraces on oops event
Usually when the kernel reaches an oops condition, it's a point of no
return; in case not enough debug information is available in the kernel
splat, one of the last resorts would be to collect a kernel crash dump
and analyze it.  The problem with this approach is that in order to
collect the dump, a panic is required (to kexec-load the crash kernel).
When in an environment of multiple virtual machines, users may prefer to
try living with the oops, at least until being able to properly shutdown
their VMs / finish their important tasks.

This patch implements a way to collect a bit more debug details when an
oops event is reached, by printing all the CPUs backtraces through the
usage of NMIs (on architectures that support that).  The sysctl added
(and documented) here was called "oops_all_cpu_backtrace", and when set
will (as the name suggests) dump all CPUs backtraces.

Far from ideal, this may be the last option though for users that for
some reason cannot panic on oops.  Most of times oopses are clear enough
to indicate the kernel portion that must be investigated, but in virtual
environments it's possible to observe hypervisor/KVM issues that could
lead to oopses shown in other guests CPUs (like virtual APIC crashes).
This patch hence aims to help debug such complex issues without
resorting to kdump.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Link: http://lkml.kernel.org/r/20200327224116.21030-1-gpiccoli@canonical.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-08 11:05:56 -07:00
Guilherme G. Piccoli
0ec9dc9bcb kernel/hung_task.c: introduce sysctl to print all traces when a hung task is detected
Commit 401c636a0e ("kernel/hung_task.c: show all hung tasks before
panic") introduced a change in that we started to show all CPUs
backtraces when a hung task is detected _and_ the sysctl/kernel
parameter "hung_task_panic" is set.  The idea is good, because usually
when observing deadlocks (that may lead to hung tasks), the culprit is
another task holding a lock and not necessarily the task detected as
hung.

The problem with this approach is that dumping backtraces is a slightly
expensive task, specially printing that on console (and specially in
many CPU machines, as servers commonly found nowadays).  So, users that
plan to collect a kdump to investigate the hung tasks and narrow down
the deadlock definitely don't need the CPUs backtrace on dmesg/console,
which will delay the panic and pollute the log (crash tool would easily
grab all CPUs traces with 'bt -a' command).

Also, there's the reciprocal scenario: some users may be interested in
seeing the CPUs backtraces but not have the system panic when a hung
task is detected.  The current approach hence is almost as embedding a
policy in the kernel, by forcing the CPUs backtraces' dump (only) on
hung_task_panic.

This patch decouples the panic event on hung task from the CPUs
backtraces dump, by creating (and documenting) a new sysctl called
"hung_task_all_cpu_backtrace", analog to the approach taken on soft/hard
lockups, that have both a panic and an "all_cpu_backtrace" sysctl to
allow individual control.  The new mechanism for dumping the CPUs
backtraces on hung task detection respects "hung_task_warnings" by not
dumping the traces in case there's no warnings left.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: http://lkml.kernel.org/r/20200327223646.20779-1-gpiccoli@canonical.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-08 11:05:56 -07:00
Rafael Aquini
db38d5c106 kernel: add panic_on_taint
Analogously to the introduction of panic_on_warn, this patch introduces
a kernel option named panic_on_taint in order to provide a simple and
generic way to stop execution and catch a coredump when the kernel gets
tainted by any given flag.

This is useful for debugging sessions as it avoids having to rebuild the
kernel to explicitly add calls to panic() into the code sites that
introduce the taint flags of interest.

For instance, if one is interested in proceeding with a post-mortem
analysis at the point a given code path is hitting a bad page (i.e.
unaccount_page_cache_page(), or slab_bug()), a coredump can be collected
by rebooting the kernel with 'panic_on_taint=0x20' amended to the
command line.

Another, perhaps less frequent, use for this option would be as a means
for assuring a security policy case where only a subset of taints, or no
single taint (in paranoid mode), is allowed for the running system.  The
optional switch 'nousertaint' is handy in this particular scenario, as
it will avoid userspace induced crashes by writes to sysctl interface
/proc/sys/kernel/tainted causing false positive hits for such policies.

[akpm@linux-foundation.org: tweak kernel-parameters.txt wording]

Suggested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Takashi Iwai <tiwai@suse.de>
Link: http://lkml.kernel.org/r/20200515175502.146720-1-aquini@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-08 11:05:56 -07:00
Linus Torvalds
b23c4771ff A fair amount of stuff this time around, dominated by yet another massive
set from Mauro toward the completion of the RST conversion.  I *really*
 hope we are getting close to the end of this.  Meanwhile, those patches
 reach pretty far afield to update document references around the tree;
 there should be no actual code changes there.  There will be, alas, more of
 the usual trivial merge conflicts.
 
 Beyond that we have more translations, improvements to the sphinx
 scripting, a number of additions to the sysctl documentation, and lots of
 fixes.
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Merge tag 'docs-5.8' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "A fair amount of stuff this time around, dominated by yet another
  massive set from Mauro toward the completion of the RST conversion. I
  *really* hope we are getting close to the end of this. Meanwhile,
  those patches reach pretty far afield to update document references
  around the tree; there should be no actual code changes there. There
  will be, alas, more of the usual trivial merge conflicts.

  Beyond that we have more translations, improvements to the sphinx
  scripting, a number of additions to the sysctl documentation, and lots
  of fixes"

* tag 'docs-5.8' of git://git.lwn.net/linux: (130 commits)
  Documentation: fixes to the maintainer-entry-profile template
  zswap: docs/vm: Fix typo accept_threshold_percent in zswap.rst
  tracing: Fix events.rst section numbering
  docs: acpi: fix old http link and improve document format
  docs: filesystems: add info about efivars content
  Documentation: LSM: Correct the basic LSM description
  mailmap: change email for Ricardo Ribalda
  docs: sysctl/kernel: document unaligned controls
  Documentation: admin-guide: update bug-hunting.rst
  docs: sysctl/kernel: document ngroups_max
  nvdimm: fixes to maintainter-entry-profile
  Documentation/features: Correct RISC-V kprobes support entry
  Documentation/features: Refresh the arch support status files
  Revert "docs: sysctl/kernel: document ngroups_max"
  docs: move locking-specific documents to locking/
  docs: move digsig docs to the security book
  docs: move the kref doc into the core-api book
  docs: add IRQ documentation at the core-api book
  docs: debugging-via-ohci1394.txt: add it to the core-api book
  docs: fix references for ipmi.rst file
  ...
2020-06-01 15:45:27 -07:00
Stephen Kitt
997c798e14 docs: sysctl/kernel: document unaligned controls
This documents ignore-unaligned-usertrap, unaligned-dump-stack, and
unaligned-trap, based on arch/arc/kernel/unaligned.c,
arch/ia64/kernel/unaligned.c, and arch/parisc/kernel/unaligned.c.

While we're at it, integrate unaligned-memory-access.txt into the docs
tree.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200515212443.5012-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-25 18:59:59 -06:00
Stephen Kitt
17444d9b0b docs: sysctl/kernel: document ngroups_max
This is a read-only export of NGROUPS_MAX.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200518145836.15816-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-25 18:59:58 -06:00
Jonathan Corbet
fdb1b5e089 Revert "docs: sysctl/kernel: document ngroups_max"
This reverts commit 2f4c33063a.

The changes here were fine, but there's a non-documentation change to
sysctl.c that makes messes elsewhere; those changes should have been done
independently.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-18 06:19:25 -06:00
Stephen Kitt
2f4c33063a docs: sysctl/kernel: document ngroups_max
This is a read-only export of NGROUPS_MAX, so this patch also changes
the declarations in kernel/sysctl.c to const.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200515160222.7994-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-15 11:24:25 -06:00
Stephen Kitt
d75829c182 docs: sysctl/kernel: document firmware_config
Based on the firmware fallback mechanisms documentation and the
implementation in drivers/base/firmware_loader/fallback.c.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200429205757.8677-2-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-05 09:53:45 -06:00
Stephen Kitt
50cdae76b8 docs: sysctl/kernel: document ftrace entries
Based on the ftrace documentation, the tp_printk boot parameter
documentation, and the implementation in kernel/trace/trace.c.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20200429205757.8677-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-05 09:53:45 -06:00
Mauro Carvalho Chehab
01478b8331 docs: filesystems: convert devpts.txt to ReST
- Add a SPDX header;
- Add a document title;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/4ac8f3a7edd4d817acf0d173ead7ef74fe010c6c.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-05 09:22:21 -06:00
Stephen Kitt
6bc47621cb docs: sysctl/kernel: document cad_pid
Based on the implementation in kernel/sysctl.c (the proc_do_cad_pid()
function), kernel/reboot.c, and include/linux/sched/signal.h.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200423183651.15365-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-28 12:39:33 -06:00
Ingo Molnar
87cfeb1920 perf/core fixes and improvements:
kernel + tools/perf:
 
   Alexey Budankov:
 
   - Introduce CAP_PERFMON to kernel and user space.
 
 callchains:
 
   Adrian Hunter:
 
   - Allow using Intel PT to synthesize callchains for regular events.
 
   Kan Liang:
 
   - Stitch LBR records from multiple samples to get deeper backtraces,
     there are caveats, see the csets for details.
 
 perf script:
 
   Andreas Gerstmayr:
 
   - Add flamegraph.py script
 
 BPF:
 
   Jiri Olsa:
 
   - Synthesize bpf_trampoline/dispatcher ksymbol events.
 
 perf stat:
 
   Arnaldo Carvalho de Melo:
 
   - Honour --timeout for forked workloads.
 
   Stephane Eranian:
 
   - Force error in fallback on :k events, to avoid counting nothing when
     the user asks for kernel events but is not allowed to.
 
 perf bench:
 
   Ian Rogers:
 
   - Add event synthesis benchmark.
 
 tools api fs:
 
   Stephane Eranian:
 
  - Make xxx__mountpoint() more scalable
 
 libtraceevent:
 
   He Zhe:
 
   - Handle return value of asprintf.
 
 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Merge tag 'perf-core-for-mingo-5.8-20200420' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core fixes and improvements from Arnaldo Carvalho de Melo:

kernel + tools/perf:

  Alexey Budankov:

  - Introduce CAP_PERFMON to kernel and user space.

callchains:

  Adrian Hunter:

  - Allow using Intel PT to synthesize callchains for regular events.

  Kan Liang:

  - Stitch LBR records from multiple samples to get deeper backtraces,
    there are caveats, see the csets for details.

perf script:

  Andreas Gerstmayr:

  - Add flamegraph.py script

BPF:

  Jiri Olsa:

  - Synthesize bpf_trampoline/dispatcher ksymbol events.

perf stat:

  Arnaldo Carvalho de Melo:

  - Honour --timeout for forked workloads.

  Stephane Eranian:

  - Force error in fallback on :k events, to avoid counting nothing when
    the user asks for kernel events but is not allowed to.

perf bench:

  Ian Rogers:

  - Add event synthesis benchmark.

tools api fs:

  Stephane Eranian:

 - Make xxx__mountpoint() more scalable

libtraceevent:

  He Zhe:

  - Handle return value of asprintf.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 14:08:28 +02:00
Stephen Kitt
5d8e5aee0e docs: sysctl/kernel: document BPF entries
Based on the implementation in kernel/bpf/syscall.c,
kernel/bpf/trampoline.c, include/linux/filter.h, and the documentation
in bpftool-prog.rst.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200315122648.20558-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-20 16:59:23 -06:00
Alexey Budankov
025b16f81d doc/admin-guide: update kernel.rst with CAP_PERFMON information
Update the kernel.rst documentation file with the information related to
usage of CAP_PERFMON capability to secure performance monitoring and
observability operations in system.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/84c32383-14a2-fa35-16b6-f9e59bd37240@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-04-16 12:19:12 -03:00
Eric Biggers
52338dfb3c docs: admin-guide: merge sections for the kernel.modprobe sysctl
Documentation for the kernel.modprobe sysctl was added both by
commit 0317c5371e ("docs: merge debugging-modules.txt into
sysctl/kernel.rst") and by commit 6e71582506 ("docs: admin-guide:
document the kernel.modprobe sysctl"), resulting in the same sysctl
being documented in two places.  Merge these into one place.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200414172430.230293-1-ebiggers@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-15 14:50:09 -06:00
Eric Biggers
6e71582506 docs: admin-guide: document the kernel.modprobe sysctl
Document the kernel.modprobe sysctl in the same place that all the other
kernel.* sysctls are documented.  Make sure to mention how to use this
sysctl to completely disable module autoloading, and how this sysctl
relates to CONFIG_STATIC_USERMODEHELPER.

[ebiggers@google.com: v5]
  Link: http://lkml.kernel.org/r/20200318230515.171692-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: NeilBrown <neilb@suse.com>
Link: http://lkml.kernel.org/r/20200312202552.241885-4-ebiggers@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-10 15:36:22 -07:00
Guilherme G. Piccoli
0a07bef6e5 Documentation: Better document the softlockup_panic sysctl
Commit 9c44bc03ff ("softlockup: allow panic on lockup") added the
softlockup_panic sysctl, but didn't add information about it to the file
Documentation/admin-guide/sysctl/kernel.rst (which in that time certainly
wasn't rst and had other name!).

This patch just adds the respective documentation and references it from
the corresponding entry in Documentation/admin-guide/kernel-parameters.txt.

This patch was strongly based on Scott Wood's commit d22881dc13
("Documentation: Better document the hardlockup_panic sysctl").

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Link: https://lore.kernel.org/r/20200310183649.23163-1-gpiccoli@canonical.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-03-10 13:55:55 -06:00
Stephen Kitt
021622df55 docs: add a script to check sysctl docs
This script allows sysctl documentation to be checked against the
kernel source code, to identify missing or obsolete entries. Running
it against 5.5 shows for example that sysctl/kernel.rst has two
obsolete entries and is missing 52 entries.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-25 03:35:16 -07:00
Stephen Kitt
2bd49cb581 docs: sysctl/kernel: document acpi_video_flags
Based on the implementation in arch/x86/kernel/acpi/sleep.c, in
particular the acpi_sleep_setup() function.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-25 03:27:23 -07:00
Stephen Kitt
8f21f54b8a docs: sysctl/kernel: remove rtsig entries
These have no corresponding code in the kernel.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19 03:34:42 -07:00
Stephen Kitt
404347e68a docs: document panic fully in sysctl/kernel.rst
The description of panic doesn’t cover all the supported scenarios;
this patch fixes that, describing the three possibilities (no reboot,
immediate reboot, reboot after a delay).

Based on the implementation in kernel/panic.c.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19 03:34:37 -07:00
Stephen Kitt
a1ad4f1505 docs: document stop-a in sysctl/kernel.rst
This describes the SPARC-specific stop-a sysctl entry, which was
previously listed in kernel.rst but not documented.

Base on the implementation in arch/sparc/kernel/setup_{32,64}.c and
kernel/panic.c.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19 03:34:32 -07:00
Stephen Kitt
fa5b526411 docs: add missing IPC documentation in sysctl/kernel.rst
This adds short descriptions of msgmax, msgmnb, msgmni, and shmmni,
which were previously listed in kernel.rst but not described.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19 03:34:25 -07:00
Stephen Kitt
a474105bb6 docs: drop l2cr from sysctl/kernel.rst
The l2cr sysctl entry was removed in commit c2f3dabefa ("sysctl:
kill binary sysctl KERN_PPC_L2CR"), this removes the corresponding
documentation.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19 03:34:20 -07:00
Stephen Kitt
0317c5371e docs: merge debugging-modules.txt into sysctl/kernel.rst
This fits nicely in sysctl/kernel.rst, merge it (and rephrase it)
instead of linking to it.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19 03:34:13 -07:00
Stephen Kitt
a3cb66a508 docs: pretty up sysctl/kernel.rst
This updates sysctl/kernel.rst to use ReStructured Text more fully:
* the list of files is now the table of contents (old entries with no
  corresponding sections are added as empty sections for now);
* code references and commands are formatted as code, except for
  function names which end up linked to the appropriate documentation;
* links are used to point to other documentation and other sections;
* tables are used to make lists of values more readable (as already
  done for some sections);
* in heavily-reworked paragraphs, sentences are wrapped individually,
  to make future diffs easier to read.

The first mention of the kernel version is dropped. The second
mention, saying that the document is accurate for 2.2, is preserved
for now; I will update that once the document really is accurate for a
current kernel release.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19 03:33:59 -07:00
d.hatayama@fujitsu.com
895f2c20a8 docs: admin-guide: Add description of %c corename format
There is somehow no description of %c corename format specifier for
/proc/sys/kernel/core_pattern. The %c corename format specifier is
used by user-space application such as systemd-coredump, so it should
be documented.

To find where %c is handled in the kernel source code, look at
function format_corename() in fs/coredump.c.

Signed-off-by: HATAYAMA Daisuke <d.hatayama@fujitsu.com>
Link: https://lore.kernel.org/r/TYAPR01MB4014714BB2ACE425BB6EC6B7951A0@TYAPR01MB4014.jpnprd01.prod.outlook.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-13 11:37:00 -07:00
Masanari Iida
e80d89380c docs: admin-guide: Remove threads-max auto-tuning
Since following path was merged in 5.4-rc3,
auto-tuning feature in threads-max does not exist any more.
Fix the admin-guide document as is.

kernel/sysctl.c: do not override max_threads provided by userspace
b0f53dbc4b

Fixes: b0f53dbc4b ("kernel/sysctl.c: do not override max_threads provided by userspace")
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-11-07 13:17:25 -07:00
Masanari Iida
73eb802ad9 docs: admin-guide: Fix min value of threads-max in kernel.rst
Since following patch was merged 5.4-rc3, minimum value for
threads-max changed to 1.

kernel/sysctl.c: do not override max_threads provided by userspace
b0f53dbc4b

Fixes: b0f53dbc4b ("kernel/sysctl.c: do not override max_threads provided by userspace")
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-11-07 13:17:24 -07:00
Oleksandr Natalenko
ca30ad857d docs: admin-guide: fix printk_ratelimit explanation
The printk_ratelimit value accepts seconds, not jiffies (though it is
converted into jiffies internally). Update documentation to reflect
this.

Also, remove the statement about allowing 1 message in 5 seconds since
bursts up to 10 messages are allowed by default.

Finally, while we are here, mention default value for
printk_ratelimit_burst too.

Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-10-10 11:34:47 -06:00
Mauro Carvalho Chehab
4f4cfa6c56 docs: admin-guide: add a series of orphaned documents
There are lots of documents that belong to the admin-guide but
are on random places (most under Documentation root dir).

Move them to the admin guide.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
2019-07-15 11:03:02 -03:00
Mauro Carvalho Chehab
5704324702 docs: admin-guide: move sysctl directory to it
The stuff under sysctl describes /sys interface from userspace
point of view. So, add it to the admin-guide and remove the
:orphan: from its index file.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-07-15 11:03:01 -03:00