linux/kernel/power
Michal Hocko 7d2e7a22cf oom, suspend: fix oom_killer_disable vs. pm suspend properly
Commit 7407054209 ("oom, suspend: fix oom_reaper vs.
oom_killer_disable race") has workaround an existing race between
oom_killer_disable and oom_reaper by adding another round of
try_to_freeze_tasks after the oom killer was disabled.  This was the
easiest thing to do for a late 4.7 fix.  Let's fix it properly now.

After "oom: keep mm of the killed task available" we no longer have to
call exit_oom_victim from the oom reaper because we have stable mm
available and hide the oom_reaped mm by MMF_OOM_SKIP flag.  So let's
remove exit_oom_victim and the race described in the above commit
doesn't exist anymore if.

Unfortunately this alone is not sufficient for the oom_killer_disable
usecase because now we do not have any reliable way to reach
exit_oom_victim (the victim might get stuck on a way to exit for an
unbounded amount of time).  OOM killer can cope with that by checking mm
flags and move on to another victim but we cannot do the same for
oom_killer_disable as we would lose the guarantee of no further
interference of the victim with the rest of the system.  What we can do
instead is to cap the maximum time the oom_killer_disable waits for
victims.  The only current user of this function (pm suspend) already
has a concept of timeout for back off so we can reuse the same value
there.

Let's drop set_freezable for the oom_reaper kthread because it is no
longer needed as the reaper doesn't wake or thaw any processes.

Link: http://lkml.kernel.org/r/1472119394-11342-7-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07 18:46:27 -07:00
..
Kconfig PM / sleep: Increase default DPM watchdog timeout to 120 2016-09-13 02:15:58 +02:00
Makefile PM / Hibernate: Don't let kasan instrument snapshot.c 2016-06-14 00:38:56 +02:00
autosleep.c PM / Sleep: avoid 'autosleep' in shutdown progress 2013-07-15 01:31:37 +02:00
console.c PM / sleep: Make pm_prepare_console() return void 2016-06-15 01:26:04 +02:00
hibernate.c PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO 2016-09-13 02:35:27 +02:00
main.c PM / sleep: enable suspend-to-idle even without registered suspend_ops 2016-09-13 02:17:19 +02:00
power.h PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO 2016-09-13 02:35:27 +02:00
poweroff.c power/sysrq: fix inconstistent help message of sysrq key 2013-04-30 17:04:10 -07:00
process.c oom, suspend: fix oom_killer_disable vs. pm suspend properly 2016-10-07 18:46:27 -07:00
qos.c PM / QoS: avoid calling cancel_delayed_work_sync() during early boot 2016-09-05 15:07:53 +02:00
snapshot.c PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO 2016-09-13 02:35:27 +02:00
suspend.c PM / sleep: enable suspend-to-idle even without registered suspend_ops 2016-09-13 02:17:19 +02:00
suspend_test.c PM / sleep: Enhance test_suspend option with repeat capability 2014-09-09 01:48:02 +02:00
swap.c Power management material for v4.8-rc1 2016-07-26 17:29:07 -07:00
user.c PM / sleep: make PM notifiers called symmetrically 2016-06-28 00:38:55 +02:00
wakelock.c PM / autosleep: Use workqueue for user space wakeup sources garbage collector 2015-07-14 21:04:48 +02:00