Since exiting tasks require write_lock_irq(&tasklist_lock) several times,
try to reduce the amount of time the readside is held for oom kills. This
makes the interface with the memcg oom handler more consistent since it
now never needs to take tasklist_lock unnecessarily.
The only time the oom killer now takes tasklist_lock is when iterating the
children of the selected task, everything else is protected by
rcu_read_lock().
This requires that a reference to the selected process, p, is grabbed
before calling oom_kill_process(). It may release it and grab a reference
on another one of p's threads if !p->mm, but it also guarantees that it
will release the reference before returning.
[hughd@google.com: fix duplicate put_task_struct()]
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The global oom killer is serialized by the per-zonelist
try_set_zonelist_oom() which is used in the page allocator. Concurrent
oom kills are thus a rare event and only occur in systems using
mempolicies and with a large number of nodes.
Memory controller oom kills, however, can frequently be concurrent since
there is no serialization once the oom killer is called for oom conditions
in several different memcgs in parallel.
This creates a massive contention on tasklist_lock since the oom killer
requires the readside for the tasklist iteration. If several memcgs are
calling the oom killer, this lock can be held for a substantial amount of
time, especially if threads continue to enter it as other threads are
exiting.
Since the exit path grabs the writeside of the lock with irqs disabled in
a few different places, this can cause a soft lockup on cpus as a result
of tasklist_lock starvation.
The kernel lacks unfair writelocks, and successful calls to the oom killer
usually result in at least one thread entering the exit path, so an
alternative solution is needed.
This patch introduces a seperate oom handler for memcgs so that they do
not require tasklist_lock for as much time. Instead, it iterates only
over the threads attached to the oom memcg and grabs a reference to the
selected thread before calling oom_kill_process() to ensure it doesn't
prematurely exit.
This still requires tasklist_lock for the tasklist dump, iterating
children of the selected process, and killing all other threads on the
system sharing the same memory as the selected victim. So while this
isn't a complete solution to tasklist_lock starvation, it significantly
reduces the amount of time that it is held.
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Sha Zhengju <handai.szj@taobao.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch introduces a helper function to process each thread during the
iteration over the tasklist. A new return type, enum oom_scan_t, is
defined to determine the future behavior of the iteration:
- OOM_SCAN_OK: continue scanning the thread and find its badness,
- OOM_SCAN_CONTINUE: do not consider this thread for oom kill, it's
ineligible,
- OOM_SCAN_ABORT: abort the iteration and return, or
- OOM_SCAN_SELECT: always select this thread with the highest badness
possible.
There is no functional change with this patch. This new helper function
will be used in the next patch in the memory controller.
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Sha Zhengju <handai.szj@taobao.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The number of ptes and swap entries are used in the oom killer's badness
heuristic, so they should be shown in the tasklist dump.
This patch adds those fields and replaces cpu and oom_adj values that are
currently emitted. Cpu isn't interesting and oom_adj is deprecated and
will be removed later this year, the same information is already displayed
as oom_score_adj which is used internally.
At the same time, make the documentation a little more clear to state this
information is helpful to determine why the oom killer chose the task it
did to kill.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
/proc/sys/vm/oom_kill_allocating_task will immediately kill current when
the oom killer is called to avoid a potentially expensive tasklist scan
for large systems.
Currently, however, it is not checking current's oom_score_adj value which
may be OOM_SCORE_ADJ_MIN, meaning that it has been disabled from oom
killing.
This patch avoids killing current in such a condition and simply falls
back to the tasklist scan since memory still needs to be freed.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The oom killer currently schedules away from current in an uninterruptible
sleep if it does not have access to memory reserves. It's possible that
current was killed because it shares memory with the oom killed thread or
because it was killed by the user in the interim, however.
This patch only schedules away from current if it does not have a pending
kill, i.e. if it does not share memory with the oom killed thread. It's
possible that it will immediately retry its memory allocation and fail,
but it will immediately be given access to memory reserves if it calls the
oom killer again.
This prevents the delay of memory freeing when threads that share memory
with the oom killed thread get unnecessarily scheduled.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix kernel-doc warnings such as
Warning(../mm/page_cgroup.c:432): No description found for parameter 'id'
Warning(../mm/page_cgroup.c:432): Excess function parameter 'mem' description in 'swap_cgroup_record'
Signed-off-by: Wanpeng Li <liwp@linux.vnet.ibm.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The divide in p->signal->oom_score_adj * totalpages / 1000 within
oom_badness() was causing an overflow of the signed long data type.
This adds both the root bias and p->signal->oom_score_adj before doing the
normalization which fixes the issue and also cleans up the calculation.
Tested-by: Dave Jones <davej@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If the privileges given to root threads (3% of allowable memory) or a
negative value of /proc/pid/oom_score_adj happen to exceed the amount of
rss of a thread, its badness score overflows as a result of commit
a7f638f999 ("mm, oom: normalize oom scores to oom_score_adj scale only
for userspace").
Fix this by making the type signed and return 1, meaning the thread is
still eligible for kill, if the value is negative.
Reported-by: Dave Jones <davej@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The oom_score_adj scale ranges from -1000 to 1000 and represents the
proportion of memory available to the process at allocation time. This
means an oom_score_adj value of 300, for example, will bias a process as
though it was using an extra 30.0% of available memory and a value of
-350 will discount 35.0% of available memory from its usage.
The oom killer badness heuristic also uses this scale to report the oom
score for each eligible process in determining the "best" process to
kill. Thus, it can only differentiate each process's memory usage by
0.1% of system RAM.
On large systems, this can end up being a large amount of memory: 256MB
on 256GB systems, for example.
This can be fixed by having the badness heuristic to use the actual
memory usage in scoring threads and then normalizing it to the
oom_score_adj scale for userspace. This results in better comparison
between eligible threads for kill and no change from the userspace
perspective.
Suggested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: Dave Jones <davej@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cred.h and a few trivial users of struct cred are changed. The rest of the users
of struct cred are left for other patches as there are too many changes to make
in one go and leave the change reviewable. If the user namespace is disabled and
CONFIG_UIDGID_STRICT_TYPE_CHECKS are disabled the code will contiue to compile
and behave correctly.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Change oom_kill_task() to use do_send_sig_info(SEND_SIG_FORCED) instead
of force_sig(SIGKILL). With the recent changes we do not need force_ to
kill the CLONE_NEWPID tasks.
And this is more correct. force_sig() can race with the exiting thread
even if oom_kill_task() checks p->mm != NULL, while
do_send_sig_info(group => true) kille the whole process.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The oom killer typically displays the allocation order at the time of oom
as a part of its diangostic messages (for global, cpuset, and mempolicy
ooms).
The memory controller may also pass the charge order to the oom killer so
it can emit the same information. This is useful in determining how large
the memory allocation is that triggered the oom killer.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The oom killer chooses not to kill a thread if:
- an eligible thread has already been oom killed and has yet to exit,
and
- an eligible thread is exiting but has yet to free all its memory and
is not the thread attempting to currently allocate memory.
SysRq+F manually invokes the global oom killer to kill a memory-hogging
task. This is normally done as a last resort to free memory when no
progress is being made or to test the oom killer itself.
For both uses, we always want to kill a thread and never defer. This
patch causes SysRq+F to always kill an eligible thread and can be used to
force a kill even if another oom killed thread has failed to exit.
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
printk_ratelimit() uses the global ratelimit state for all printks. The
oom killer should not be subjected to this state just because another
subsystem or driver may be flooding the kernel log.
This patch introduces printk ratelimiting specifically for the oom killer.
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If a thread is chosen for oom kill and is already PF_EXITING, then the oom
killer simply sets TIF_MEMDIE and returns. This allows the thread to have
access to memory reserves so that it may quickly exit. This logic is
preceeded with a comment saying there's no need to alarm the sysadmin.
This patch adds truth to that statement.
There's no need to emit any warning about the oom condition if the thread
is already exiting since it will not be killed. In this condition, just
silently return the oom killer since its only giving access to memory
reserves and is otherwise a no-op.
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
oom_kill_task() returns non-zero iff the chosen process does not have any
threads with an attached ->mm.
In such a case, it's better to just return to the page allocator and retry
the allocation because memory could have been freed in the interim and the
oom condition may no longer exist. It's unnecessary to loop in the oom
killer and find another thread to kill.
This allows both oom_kill_task() and oom_kill_process() to be converted to
void functions. If the oom condition persists, the oom killer will be
recalled.
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
oom_score_adj is used for guarding processes from OOM-Killer. One of
problem is that it's inherited at fork(). When a daemon set oom_score_adj
and make children, it's hard to know where the value is set.
This patch adds some tracepoints useful for debugging. This patch adds
3 trace points.
- creating new task
- renaming a task (exec)
- set oom_score_adj
To debug, users need to enable some trace pointer. Maybe filtering is useful as
# EVENT=/sys/kernel/debug/tracing/events/task/
# echo "oom_score_adj != 0" > $EVENT/task_newtask/filter
# echo "oom_score_adj != 0" > $EVENT/task_rename/filter
# echo 1 > $EVENT/enable
# EVENT=/sys/kernel/debug/tracing/events/oom/
# echo 1 > $EVENT/enable
output will be like this.
# grep oom /sys/kernel/debug/tracing/trace
bash-7699 [007] d..3 5140.744510: oom_score_adj_update: pid=7699 comm=bash oom_score_adj=-1000
bash-7699 [007] ...1 5151.818022: task_newtask: pid=7729 comm=bash clone_flags=1200011 oom_score_adj=-1000
ls-7729 [003] ...2 5151.818504: task_rename: pid=7729 oldcomm=bash newcomm=ls oom_score_adj=-1000
bash-7699 [002] ...1 5175.701468: task_newtask: pid=7730 comm=bash clone_flags=1200011 oom_score_adj=-1000
grep-7730 [007] ...2 5175.701993: task_rename: pid=7730 oldcomm=bash newcomm=grep oom_score_adj=-1000
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* master: (848 commits)
SELinux: Fix RCU deref check warning in sel_netport_insert()
binary_sysctl(): fix memory leak
mm/vmalloc.c: remove static declaration of va from __get_vm_area_node
ipmi_watchdog: restore settings when BMC reset
oom: fix integer overflow of points in oom_badness
memcg: keep root group unchanged if creation fails
nilfs2: potential integer overflow in nilfs_ioctl_clean_segments()
nilfs2: unbreak compat ioctl
cpusets: stall when updating mems_allowed for mempolicy or disjoint nodemask
evm: prevent racing during tfm allocation
evm: key must be set once during initialization
mmc: vub300: fix type of firmware_rom_wait_states module parameter
Revert "mmc: enable runtime PM by default"
mmc: sdhci: remove "state" argument from sdhci_suspend_host
x86, dumpstack: Fix code bytes breakage due to missing KERN_CONT
IB/qib: Correct sense on freectxts increment and decrement
RDMA/cma: Verify private data length
cgroups: fix a css_set not found bug in cgroup_attach_proc
oprofile: Fix uninitialized memory access when writing to writing to oprofilefs
Revert "xen/pv-on-hvm kexec: add xs_reset_watches to shutdown watches from old kernel"
...
Conflicts:
kernel/cgroup_freezer.c
Davidlohr Bueso
David Rientjes
Andrew Morton
Wanpeng Li
Eric W. Biederman
Oleg Nesterov
Johannes Weiner
KAMEZAWA Hiroyuki
Rafael J. Wysocki