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Commit 8e675f7a authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Linus Torvalds
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mm/oom_kill: count global and memory cgroup oom kills 

Show count of oom killer invocations in /proc/vmstat and count of
processes killed in memory cgroup in knob "memory.events" (in
memory.oom_control for v1 cgroup).

Also describe difference between "oom" and "oom_kill" in memory cgroup
documentation.  Currently oom in memory cgroup kills tasks iff shortage
has happened inside page fault.

These counters helps in monitoring oom kills - for now the only way is
grepping for magic words in kernel log.

[akpm@linux-foundation.org: fix for mem_cgroup_count_vm_event() rename]
[akpm@linux-foundation.org: fix comment, per Konstantin]
Link: http://lkml.kernel.org/r/149570810989.203600.9492483715840752937.stgit@buzz


Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Roman Guschin <guroan@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2262185c

Documentation/cgroup-v2.txt

+16 −4
Original line number Diff line number Diff line
@@ -852,13 +852,25 @@ PAGE_SIZE multiple when read back. 


		The number of times the cgroup's memory usage was

		about to go over the max boundary.  If direct reclaim

		fails to bring it down, the OOM killer is invoked.

		fails to bring it down, the cgroup goes to OOM state.



	  oom



		The number of times the OOM killer has been invoked in

		the cgroup.  This may not exactly match the number of

		processes killed but should generally be close.

		The number of time the cgroup's memory usage was

		reached the limit and allocation was about to fail.



		Depending on context result could be invocation of OOM

		killer and retrying allocation or failing alloction.



		Failed allocation in its turn could be returned into

		userspace as -ENOMEM or siletly ignored in cases like

		disk readahead.	 For now OOM in memory cgroup kills

		tasks iff shortage has happened inside page fault.



	  oom_kill



		The number of processes belonging to this cgroup

		killed by any kind of OOM killer.



  memory.stat

include/linux/memcontrol.h

+4 −1
Original line number Diff line number Diff line
@@ -582,8 +582,11 @@ static inline void count_memcg_event_mm(struct mm_struct *mm, 


	rcu_read_lock();

	memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));

	if (likely(memcg))

	if (likely(memcg)) {

		this_cpu_inc(memcg->stat->events[idx]);

		if (idx == OOM_KILL)

			cgroup_file_notify(&memcg->events_file);

	}

	rcu_read_unlock();

}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

include/linux/vm_event_item.h

+1 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, 
		KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,

		PAGEOUTRUN, PGROTATED,

		DROP_PAGECACHE, DROP_SLAB,

		OOM_KILL,

#ifdef CONFIG_NUMA_BALANCING

		NUMA_PTE_UPDATES,

		NUMA_HUGE_PTE_UPDATES,

mm/memcontrol.c

+2 −0
Original line number Diff line number Diff line
@@ -3573,6 +3573,7 @@ static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v) 


	seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable);

	seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom);

	seq_printf(sf, "oom_kill %lu\n", memcg_sum_events(memcg, OOM_KILL));

	return 0;

}
@@ -5164,6 +5165,7 @@ static int memory_events_show(struct seq_file *m, void *v) 
	seq_printf(m, "high %lu\n", memcg_sum_events(memcg, MEMCG_HIGH));

	seq_printf(m, "max %lu\n", memcg_sum_events(memcg, MEMCG_MAX));

	seq_printf(m, "oom %lu\n", memcg_sum_events(memcg, MEMCG_OOM));

	seq_printf(m, "oom_kill %lu\n", memcg_sum_events(memcg, OOM_KILL));



	return 0;

}

mm/oom_kill.c

+5 −0
Original line number Diff line number Diff line
@@ -876,6 +876,11 @@ static void oom_kill_process(struct oom_control *oc, const char *message) 
	/* Get a reference to safely compare mm after task_unlock(victim) */

	mm = victim->mm;

	mmgrab(mm);



	/* Raise event before sending signal: task reaper must see this */

	count_vm_event(OOM_KILL);

	count_memcg_event_mm(mm, OOM_KILL);



	/*

	 * We should send SIGKILL before setting TIF_MEMDIE in order to prevent

	 * the OOM victim from depleting the memory reserves from the user