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: Konstantin 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
index 5ac2fbd..e610197 100644
--- a/Documentation/cgroup-v2.txt
+++ b/Documentation/cgroup-v2.txt
@@ -852,13 +852,25 @@
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
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index b2a5b1c..72d0853 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -582,8 +582,11 @@
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
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index be3ab2d..37e8d31 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -41,6 +41,7 @@
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,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3e2f8cf..4f686fc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3573,6 +3573,7 @@
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 @@
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;
}
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 04c9143..0e2c925 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -876,6 +876,11 @@
/* 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
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 6dae6b2..4628182 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1018,6 +1018,7 @@
"drop_pagecache",
"drop_slab",
+ "oom_kill",
#ifdef CONFIG_NUMA_BALANCING
"numa_pte_updates",