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After the recent cgroup_kn_lock_live() changes, cgroup_mutex is no
longer nested below kernfs active protection. The two don't have any
relationship now.
This patch nests kernfs active protection under cgroup_mutex. All
cftype operations now require both cgroup_tree_mutex and cgroup_mutex,
temporary cgroup_mutex releases over kernfs operations are removed,
and cgroup_add/rm_cftypes() grab both mutexes.
This makes cgroup_tree_mutex redundant, which will be removed by the
next patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Make __cgroup_procs_write() and cgroup_release_agent_write() use
cgroup_kn_lock_live() and cgroup_kn_unlock() instead of
cgroup_lock_live_group(). This puts the operations under both
cgroup_tree_mutex and cgroup_mutex protection without circular
dependency from kernfs active protection. Also, this means that
cgroup_mutex is no longer nested below kernfs active protection.
There is no longer any place where the two locks interact.
This leaves cgroup_lock_live_group() without any user. Removed.
This will help simplifying cgroup locking.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup_mkdir(), cgroup_rmdir() and cgroup_subtree_control_write()
share the logic to break active protection so that they can grab
cgroup_tree_mutex which nests above active protection and/or remove
self. Factor out this logic into cgroup_kn_lock_live() and
cgroup_kn_unlock().
This patch doesn't introduce any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
The ->priv field of a cgroup directory kernfs_node points back to the
cgroup. This field is RCU cleared in cgroup_destroy_locked() for
non-kernfs accesses from css_tryget_from_dir() and
cgroupstats_build().
As these are only applicable to cgroups which finished creation
successfully and fully initialized cgroups are always removed by
cgroup_rmdir(), this can be safely moved to the end of cgroup_rmdir().
This will help simplifying cgroup locking and shouldn't introduce any
behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Move cgroup_lock_live_group() invocation upwards to right below
cgroup_tree_mutex in cgroup_subtree_control_write(). This is to help
the planned locking simplification.
This doesn't make any userland-visible behavioral changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup_mkdir() is the sole user of cgroup_create(). Let's collapse
the latter into the former. This will help simplifying locking.
While at it, remove now stale comment about inode locking.
This patch doesn't introduce any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Reorganize cgroup_create() so that all paths share unlock out path.
* All err_* labels are renamed to out_* as they're now shared by both
success and failure paths.
* @err renamed to @ret for the similar reason as above and so that
it's more consistent with other functions.
* cgroup memory allocation moved after locking so that freeing failed
cgroup happens before unlocking. While this moves more code inside
critical section, memory allocations inside cgroup locking are
already pretty common and this is unlikely to make any noticeable
difference.
* While at it, replace a stray @parent->root dereference with @root.
This reorganization will help simplifying locking.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Now that cgroup_subtree_control_write() has access to the associated
kernfs_open_file and thus the kernfs_node, there's no need to cache it
in cgroup->control_kn on creation. Remove cgroup->control_kn and use
@of->kn directly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup_tasks_write() and cgroup_procs_write() are currently using
cftype->write_u64(). This patch converts them to use cftype->write()
instead. This allows access to the associated kernfs_open_file which
will be necessary to implement the planned kernfs active protection
manipulation for these files.
This shifts buffer parsing to attach_task_by_pid() and makes it return
@nbytes on success. Let's rename it to __cgroup_procs_write() to
clearly indicate that this is a write handler implementation.
This patch doesn't introduce any visible behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cftype->trigger() is pointless. It's trivial to ignore the input
buffer from a regular ->write() operation. Convert all ->trigger()
users to ->write() and remove ->trigger().
This patch doesn't introduce any visible behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Convert all cftype->write_string() users to the new cftype->write()
which maps directly to kernfs write operation and has full access to
kernfs and cgroup contexts. The conversions are mostly mechanical.
* @css and @cft are accessed using of_css() and of_cft() accessors
respectively instead of being specified as arguments.
* Should return @nbytes on success instead of 0.
* @buf is not trimmed automatically. Trim if necessary. Note that
blkcg and netprio don't need this as the parsers already handle
whitespaces.
cftype->write_string() has no user left after the conversions and
removed.
While at it, remove unnecessary local variable @p in
cgroup_subtree_control_write() and stale comment about
CGROUP_LOCAL_BUFFER_SIZE in cgroup_freezer.c.
This patch doesn't introduce any visible behavior changes.
v2: netprio was missing from conversion. Converted.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: "David S. Miller" <davem@davemloft.net>
During the recent conversion to kernfs, cftype's seq_file operations
are updated so that they are directly mapped to kernfs operations and
thus can fully access the associated kernfs and cgroup contexts;
however, write path hasn't seen similar updates and none of the
existing write operations has access to, for example, the associated
kernfs_open_file.
Let's introduce a new operation cftype->write() which maps directly to
the kernfs write operation and has access to all the arguments and
contexts. This will replace ->write_string() and ->trigger() and ease
manipulation of kernfs active protection from cgroup file operations.
Two accessors - of_cft() and of_css() - are introduced to enable
accessing the associated cgroup context from cftype->write() which
only takes kernfs_open_file for the context information. The
accessors for seq_file operations - seq_cft() and seq_css() - are
rewritten to wrap the of_ accessors.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Unlike the more usual refcnting, what css_tryget() provides is the
distinction between online and offline csses instead of protection
against upping a refcnt which already reached zero. cgroup is
planning to provide actual tryget which fails if the refcnt already
reached zero. Let's rename the existing trygets so that they clearly
indicate that they're onliness.
I thought about keeping the existing names as-are and introducing new
names for the planned actual tryget; however, given that each
controller participates in the synchronization of the online state, it
seems worthwhile to make it explicit that these functions are about
on/offline state.
Rename css_tryget() to css_tryget_online() and css_tryget_from_dir()
to css_tryget_online_from_dir(). This is pure rename.
v2: cgroup_freezer grew new usages of css_tryget(). Update
accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
release_path is now protected by release_agent_path_lock to allow
accessing it without grabbing cgroup_mutex; however,
cgroup_release_agent_show() was still grabbing cgroup_mutex. Let's
convert it to release_agent_path_lock so that we don't have to worry
about this one for the planned locking updates.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
After waiting for a child to finish offline,
cgroup_subtree_control_write() jumps up to retry from after the input
parsing and active protection breaking. This retry makes the
scheduled locking update - removal of cgroup_tree_mutex - more
difficult. Let's simplify it by returning with restart_syscall() for
retries.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
I was confused that strsep() was equivalent to strtok_r() in skipping
over consecutive delimiters. strsep() just splits at the first
occurrence of one of the delimiters which makes the parsing very
inflexible, which makes allowing multiple whitespace chars as
delimters kinda moot. Let's just be consistently strict and require
list of tokens separated by spaces. This is what
Documentation/cgroups/unified-hierarchy.txt describes too.
Also, parsing may access beyond the end of the string if the string
ends with spaces or is zero-length. Make sure it skips zero-length
tokens. Note that this also ensures that the parser doesn't puke on
multiple consecutive spaces.
v2: Add zero-length token skipping.
v3: Added missing space after "==". Spotted by Li.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
c1a71504e971 ("cgroup: don't recycle cgroup id until all csses' have
been destroyed") made cgroup ID persist until a cgroup is released and
add cgroup->subsys[] clearing to css_release() so that css_from_id()
doesn't return a css which has already been released which happens
before cgroup release; however, the right change here was updating
offline_css() to clear cgroup->subsys[] which was done by e32978031016
("cgroup: cgroup->subsys[] should be cleared after the css is
offlined") instead of clearing it from css_release().
We're now clearing cgroup->subsys[] twice. This is okay for
traditional hierarchies as a css's lifetime is the same as its
cgroup's; however, this confuses unified hierarchy and turning on and
off a controller repeatedly using "cgroup.subtree_control" can lead to
an oops like the following which happens because cgroup->subsys[] is
incorrectly cleared asynchronously by css_release().
BUG: unable to handle kernel NULL pointer dereference at 00000000000000 08
IP: [<ffffffff81130c11>] kill_css+0x21/0x1c0
PGD 1170d067 PUD f0ab067 PMD 0
Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Modules linked in:
CPU: 2 PID: 459 Comm: bash Not tainted 3.15.0-rc2-work+ #5
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
task: ffff880009296710 ti: ffff88000e198000 task.ti: ffff88000e198000
RIP: 0010:[<ffffffff81130c11>] [<ffffffff81130c11>] kill_css+0x21/0x1c0
RSP: 0018:ffff88000e199dc8 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000001 RSI: ffffffff8238a968 RDI: ffff880009296f98
RBP: ffff88000e199de0 R08: 0000000000000001 R09: 02b0000000000000
R10: 0000000000000000 R11: ffff880009296fc0 R12: 0000000000000001
R13: ffff88000db6fc58 R14: 0000000000000001 R15: ffff8800139dcc00
FS: 00007ff9160c5740(0000) GS:ffff88001fb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000013947000 CR4: 00000000000006e0
Stack:
ffff88000e199de0 ffffffff82389160 0000000000000001 ffff88000e199e80
ffffffff8113537f 0000000000000007 ffff88000e74af00 ffff88000e199e48
ffff880009296710 ffff88000db6fc00 ffffffff8239c100 0000000000000002
Call Trace:
[<ffffffff8113537f>] cgroup_subtree_control_write+0x85f/0xa00
[<ffffffff8112fd18>] cgroup_file_write+0x38/0x1d0
[<ffffffff8126fc97>] kernfs_fop_write+0xe7/0x170
[<ffffffff811f2ae6>] vfs_write+0xb6/0x1c0
[<ffffffff811f35ad>] SyS_write+0x4d/0xc0
[<ffffffff81d0acd2>] system_call_fastpath+0x16/0x1b
Code: 5c 41 5d 41 5e 41 5f 5d c3 90 0f 1f 44 00 00 55 48 89 e5 41 54 53 48 89 fb 48 83 ec 08 8b 05 37 ad 29 01 85 c0 0f 85 df 00 00 00 <48> 8b 43 08 48 8b 3b be 01 00 00 00 8b 48 5c d3 e6 e8 49 ff ff
RIP [<ffffffff81130c11>] kill_css+0x21/0x1c0
RSP <ffff88000e199dc8>
CR2: 0000000000000008
---[ end trace e7aae1f877c4e1b4 ]---
Remove the unnecessary cgroup->subsys[] clearing from css_release().
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup_idr_remove() can be invoked from bh leading to lockdep
detecting possible AA deadlock (IN_BH/ON_BH). Make the lock bh-safe.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroup_subtree_control_write() waits for offline to complete
child-by-child before enabling a controller; however, it has a couple
bugs.
* It doesn't initialize the wait_queue_t. This can lead to infinite
hang on the following schedule() among other things.
* It forgets to pin the child before releasing cgroup_tree_mutex and
performing schedule(). The child may already be gone by the time it
wakes up and invokes finish_wait(). Pin the child being waited on.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Pull to receive e37a06f10994 ("cgroup: fix the retry path of
cgroup_mount()") to avoid unnecessary conflicts with planned
cgroup_tree_mutex removal and also to be able to remove the temp fix
added by 36c38fb7144a ("blkcg: use trylock on blkcg_pol_mutex in
blkcg_reset_stats()") afterwards.
Signed-off-by: Tejun Heo <tj@kernel.org>
While updating cgroup_freezer locking, 68fafb77d827 ("cgroup_freezer:
replace freezer->lock with freezer_mutex") introduced a bug in
update_if_frozen() where it returns with rcu_read_lock() held. Fix it
by adding rcu_read_unlock() before returning.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
After 96d365e0b86e ("cgroup: make css_set_lock a rwsem and rename it
to css_set_rwsem"), css task iterators requires sleepable context as
it may block on css_set_rwsem. I missed that cgroup_freezer was
iterating tasks under IRQ-safe spinlock freezer->lock. This leads to
errors like the following on freezer state reads and transitions.
BUG: sleeping function called from invalid context at /work
/os/work/kernel/locking/rwsem.c:20
in_atomic(): 0, irqs_disabled(): 0, pid: 462, name: bash
5 locks held by bash/462:
#0: (sb_writers#7){.+.+.+}, at: [<ffffffff811f0843>] vfs_write+0x1a3/0x1c0
#1: (&of->mutex){+.+.+.}, at: [<ffffffff8126d78b>] kernfs_fop_write+0xbb/0x170
#2: (s_active#70){.+.+.+}, at: [<ffffffff8126d793>] kernfs_fop_write+0xc3/0x170
#3: (freezer_mutex){+.+...}, at: [<ffffffff81135981>] freezer_write+0x61/0x1e0
#4: (rcu_read_lock){......}, at: [<ffffffff81135973>] freezer_write+0x53/0x1e0
Preemption disabled at:[<ffffffff81104404>] console_unlock+0x1e4/0x460
CPU: 3 PID: 462 Comm: bash Not tainted 3.15.0-rc1-work+ #10
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
ffff88000916a6d0 ffff88000e0a3da0 ffffffff81cf8c96 0000000000000000
ffff88000e0a3dc8 ffffffff810cf4f2 ffffffff82388040 ffff880013aaf740
0000000000000002 ffff88000e0a3de8 ffffffff81d05974 0000000000000246
Call Trace:
[<ffffffff81cf8c96>] dump_stack+0x4e/0x7a
[<ffffffff810cf4f2>] __might_sleep+0x162/0x260
[<ffffffff81d05974>] down_read+0x24/0x60
[<ffffffff81133e87>] css_task_iter_start+0x27/0x70
[<ffffffff8113584d>] freezer_apply_state+0x5d/0x130
[<ffffffff81135a16>] freezer_write+0xf6/0x1e0
[<ffffffff8112eb88>] cgroup_file_write+0xd8/0x230
[<ffffffff8126d7b7>] kernfs_fop_write+0xe7/0x170
[<ffffffff811f0756>] vfs_write+0xb6/0x1c0
[<ffffffff811f121d>] SyS_write+0x4d/0xc0
[<ffffffff81d08292>] system_call_fastpath+0x16/0x1b
freezer->lock used to be used in hot paths but that time is long gone
and there's no reason for the lock to be IRQ-safe spinlock or even
per-cgroup. In fact, given the fact that a cgroup may contain large
number of tasks, it's not a good idea to iterate over them while
holding IRQ-safe spinlock.
Let's simplify locking by replacing per-cgroup freezer->lock with
global freezer_mutex. This also makes the comments explaining the
intricacies of policy inheritance and the locking around it as the
states are protected by a common mutex.
The conversion is mostly straight-forward. The followings are worth
mentioning.
* freezer_css_online() no longer needs double locking.
* freezer_attach() now performs propagation simply while holding
freezer_mutex. update_if_frozen() race no longer exists and the
comment is removed.
* freezer_fork() now tests whether the task is in root cgroup using
the new task_css_is_root() without doing rcu_read_lock/unlock(). If
not, it grabs freezer_mutex and performs the operation.
* freezer_read() and freezer_change_state() grab freezer_mutex across
the whole operation and pin the css while iterating so that each
descendant processing happens in sleepable context.
Fixes: 96d365e0b86e ("cgroup: make css_set_lock a rwsem and rename it to css_set_rwsem")
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Determining the css of a task usually requires RCU read lock as that's
the only thing which keeps the returned css accessible till its
reference is acquired; however, testing whether a task belongs to the
root can be performed without dereferencing the returned css by
comparing the returned pointer against the root one in init_css_set[]
which never changes.
Implement task_css_is_root() which can be invoked in any context.
This will be used by the scheduled cgroup_freezer change.
v2: cgroup no longer supports modular controllers. No need to export
init_css_set. Pointed out by Li.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Pull workqueue fixes from Tejun Heo:
"Fixes for two bugs in workqueue.
One is exiting with internal mutex held in a failure path of
wq_update_unbound_numa(). The other is a subtle and unlikely
use-after-possible-last-put in the rescuer logic. Both have been
around for quite some time now and are unlikely to have triggered
noticeably often. All patches are marked for -stable backport"
* 'for-3.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: fix a possible race condition between rescuer and pwq-release
workqueue: make rescuer_thread() empty wq->maydays list before exiting
workqueue: fix bugs in wq_update_unbound_numa() failure path
Pull cgroup fixes from Tejun Heo:
"During recent restructuring, device_cgroup unified config input check
and enforcement logic; unfortunately, it turned out to share too much.
Aristeu's patches fix the breakage and marked for -stable backport.
The other two patches are fallouts from kernfs conversion. The blkcg
change is temporary and will go away once kernfs internal locking gets
simplified (patches pending)"
* 'for-3.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
blkcg: use trylock on blkcg_pol_mutex in blkcg_reset_stats()
device_cgroup: check if exception removal is allowed
device_cgroup: fix the comment format for recently added functions
device_cgroup: rework device access check and exception checking
cgroup: fix the retry path of cgroup_mount()
is_error_status() is an inline function always called with the
global time_status as an argument, so there's zero functional
difference with this change, but the non-CONFIG_NTP_PPS version
uses the passed-in argument, while the CONFIG_NTP_PPS one ignores
its argument and uses the global.
Looks like is_error_status was refactored out, but someone forgot
to change the logic to check the local argument value.
Thus this patch makes it use the argument always; shorter variable
names are good.
Signed-off-by: George Spelvin <linux@horizon.com>
[jstultz: Tweaked commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
tj: Refreshed on top of wq/for-3.16.
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Tejun Heo <tj@kernel.org>
Conflicts:
drivers/net/ethernet/altera/altera_sgdma.c
net/netlink/af_netlink.c
net/sched/cls_api.c
net/sched/sch_api.c
The netlink conflict dealt with moving to netlink_capable() and
netlink_ns_capable() in the 'net' tree vs. supporting 'tc' operations
in non-init namespaces. These were simple transformations from
netlink_capable to netlink_ns_capable.
The Altera driver conflict was simply code removal overlapping some
void pointer cast cleanups in net-next.
Signed-off-by: David S. Miller <davem@davemloft.net>
Replace obsolete function simple_strtol w/ kstrtol
Inspired-By: Andrew Morton <akpm@linux-foundation.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
[jstultz: Tweak commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Replace obsolete function.
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Pull x86 fixes from Peter Anvin:
"A somewhat unpleasantly large collection of small fixes. The big ones
are the __visible tree sweep and a fix for 'earlyprintk=efi,keep'. It
was using __init functions with predictably suboptimal results.
Another key fix is a build fix which would produce output that simply
would not decompress correctly in some configuration, due to the
existing Makefiles picking up an unfortunate local label and mistaking
it for the global symbol _end.
Additional fixes include the handling of 64-bit numbers when setting
the vdso data page (a latent bug which became manifest when i386
started exporting a vdso with time functions), a fix to the new MSR
manipulation accessors which would cause features to not get properly
unblocked, a build fix for 32-bit userland, and a few new platform
quirks"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, vdso, time: Cast tv_nsec to u64 for proper shifting in update_vsyscall()
x86: Fix typo in MSR_IA32_MISC_ENABLE_LIMIT_CPUID macro
x86: Fix typo preventing msr_set/clear_bit from having an effect
x86/intel: Add quirk to disable HPET for the Baytrail platform
x86/hpet: Make boot_hpet_disable extern
x86-64, build: Fix stack protector Makefile breakage with 32-bit userland
x86/reboot: Add reboot quirk for Certec BPC600
asmlinkage: Add explicit __visible to drivers/*, lib/*, kernel/*
asmlinkage, x86: Add explicit __visible to arch/x86/*
asmlinkage: Revert "lto: Make asmlinkage __visible"
x86, build: Don't get confused by local symbols
x86/efi: earlyprintk=efi,keep fix
The first is a long standing bug that causes bogus data to show up
in the refcnt field of the module_refcnt tracepoint. It was
introduced by a merge conflict resolution back in 2.6.35-rc days.
The result should be refcnt = incs - decs, but instead it did
refcnt = incs + decs.
The second fix is to a bug that was introduced in this merge window
that allowed for a tracepoint funcs pointer to be used after it
was freed. Moving the location of where the probes are released
solved the problem.
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Merge tag 'trace-fixes-v3.15-rc4-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
"This contains two fixes.
The first is a long standing bug that causes bogus data to show up in
the refcnt field of the module_refcnt tracepoint. It was introduced
by a merge conflict resolution back in 2.6.35-rc days.
The result should be 'refcnt = incs - decs', but instead it did
'refcnt = incs + decs'.
The second fix is to a bug that was introduced in this merge window
that allowed for a tracepoint funcs pointer to be used after it was
freed. Moving the location of where the probes are released solved
the problem"
* tag 'trace-fixes-v3.15-rc4-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracepoint: Fix use of tracepoint funcs after rcu free
trace: module: Maintain a valid user count
Commit de7b2973903c "tracepoint: Use struct pointer instead of name hash
for reg/unreg tracepoints" introduces a use after free by calling
release_probes on the old struct tracepoint array before the newly
allocated array is published with rcu_assign_pointer. There is a race
window where tracepoints (RCU readers) can perform a
"use-after-grace-period-after-free", which shows up as a GPF in
stress-tests.
Link: http://lkml.kernel.org/r/53698021.5020108@oracle.com
Link: http://lkml.kernel.org/p/1399549669-25465-1-git-send-email-mathieu.desnoyers@efficios.com
Reported-by: Sasha Levin <sasha.levin@oracle.com>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Dave Jones <davej@redhat.com>
Fixes: de7b2973903c "tracepoint: Use struct pointer instead of name hash for reg/unreg tracepoints"
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The only value ever returned by cpuidle_idle_call() is 0 and its
only caller ignores that value anyway, so make it void.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/4717784.WmVEpDoliM@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With the generic idle functions assuming !polling we should only clear
the polling bit at the very last opportunity in order to avoid
spurious IPIs.
Ideally we'd flip the default to polling, but that means auditing all
arch idle functions.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-vq7719foqzf6z5h4j7eh7f9e@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Because mwait_idle_with_hints() gets called from !idle context it must
call current_clr_polling(). This however means that resched_task() is
very likely to send an IPI even when we were polling:
CPU0 CPU1
if (current_set_polling_and_test())
goto out;
__monitor(&ti->flags);
if (!need_resched())
__mwait(eax, ecx);
set_tsk_need_resched(p);
smp_mb();
out:
current_clr_polling();
if (!tsk_is_polling(p))
smp_send_reschedule(cpu);
So while it is correct (extra IPIs aren't a problem, whereas a missed
IPI would be) it is a performance problem (for some).
Avoid this issue by using fetch_or() to atomically set NEED_RESCHED
and test if POLLING_NRFLAG is set.
Since a CPU stuck in mwait is unlikely to modify the flags word,
contention on the cmpxchg is unlikely and thus we should mostly
succeed in a single go.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-kf5suce6njh5xf5d3od13rr0@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of jumping through hoops to make sure to find (and exit) each
event, do it the simple straight fwd way.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-tij931199thfkys8vbnokdpf@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Primarily make perf_event_release_kernel() into put_event(), this will
allow kernel space to create per-task inherited events, and is safer
in general.
Also, document the free_event() assumptions.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-rk9pvr6e1d0559lxstltbztc@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 38b435b16c36 ("perf: Fix tear-down of inherited group events")
states that we need to destroy groups for inherited events, but it
doesn't make any sense to not also destroy groups for normal events.
And while it usually makes no difference (the normal events won't
leak, and its very likely all the group events will die in quick
succession) it does make the code more consistent and closes a
potential hole for trouble.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-426egt8zmsm12d2q8k2xz4tt@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Make sure all events in a group have the same inherit state. It was
possible for group leaders to have inherit set while sibling events
would not have inherit set.
In this case we'd still inherit the siblings, leading to some
non-fatal weirdness.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-r32tt8yldvic3jlcghd3g35u@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It was found that when running some workloads (such as AIM7) on large
systems with many cores, CPUs do not remain idle for long. Thus, tasks
can wake/get enqueued while doing idle balancing.
In this patch, while traversing the domains in idle balance, in
addition to checking for pulled_task, we add an extra check for
this_rq->nr_running for determining if we should stop searching for
tasks to pull. If there are runnable tasks on this rq, then we will
stop traversing the domains. This reduces the chance that idle balance
delays a task from running.
This patch resulted in approximately a 6% performance improvement when
running a Java Server workload on an 8 socket machine.
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: daniel.lezcano@linaro.org
Cc: alex.shi@linaro.org
Cc: preeti@linux.vnet.ibm.com
Cc: efault@gmx.de
Cc: vincent.guittot@linaro.org
Cc: morten.rasmussen@arm.com
Cc: aswin@hp.com
Cc: chegu_vinod@hp.com
Link: http://lkml.kernel.org/r/1398303035-18255-4-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A new flag SD_SHARE_POWERDOMAIN is created to reflect whether groups of CPUs
in a sched_domain level can or not reach different power state. As an example,
the flag should be cleared at CPU level if groups of cores can be power gated
independently. This information can be used in the load balance decision or to
add load balancing level between group of CPUs that can power gate
independantly.
This flag is part of the topology flags that can be set by arch.
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: schwidefsky@de.ibm.com
Cc: cmetcalf@tilera.com
Cc: benh@kernel.crashing.org
Cc: preeti@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1397209481-28542-5-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We replace the old way to configure the scheduler topology with a new method
which enables a platform to declare additionnal level (if needed).
We still have a default topology table definition that can be used by platform
that don't want more level than the SMT, MC, CPU and NUMA ones. This table can
be overwritten by an arch which either wants to add new level where a load
balance make sense like BOOK or powergating level or wants to change the flags
configuration of some levels.
For each level, we need a function pointer that returns cpumask for each cpu,
a function pointer that returns the flags for the level and a name. Only flags
that describe topology, can be set by an architecture. The current topology
flags are:
SD_SHARE_CPUPOWER
SD_SHARE_PKG_RESOURCES
SD_NUMA
SD_ASYM_PACKING
Then, each level must be a subset on the next one. The build sequence of the
sched_domain will take care of removing useless levels like those with 1 CPU
and those with the same CPU span and no more relevant information for
load balancing than its children.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux390@de.ibm.com
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Link: http://lkml.kernel.org/r/1397209481-28542-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Setting the numa_preferred_node for a task in task_numa_migrate
does nothing on a 2-node system. Either we migrate to the node
that already was our preferred node, or we stay where we were.
On a 4-node system, it can slightly decrease overhead, by not
calling the NUMA code as much. Since every node tends to be
directly connected to every other node, running on the wrong
node for a while does not do much damage.
However, on an 8 node system, there are far more bad nodes
than there are good ones, and pretending that a second choice
is actually the preferred node can greatly delay, or even
prevent, a workload from converging.
The only time we can safely pretend that a second choice
node is the preferred node is when the task is part of a
workload that spans multiple NUMA nodes.
Signed-off-by: Rik van Riel <riel@redhat.com>
Tested-by: Vinod Chegu <chegu_vinod@hp.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1397235629-16328-4-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
