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Date: Thu, 25 May 2017 13:28:30 +0300
From: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Michal Hocko <mhocko@...nel.org>
Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
Andrew Morton <akpm@...ux-foundation.org>,
Roman Guschin <guroan@...il.com>,
David Rientjes <rientjes@...gle.com>
Subject: [PATCH v2] 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.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
---
v1: https://lkml.kernel.org/r/149520375057.74196.2843113275800730971.stgit@buzz
v2:
* count all oom kills in /proc/vmstat
* update counter for cgroup which tasks belongs to
---
Documentation/cgroup-v2.txt | 20 ++++++++++++++++----
include/linux/memcontrol.h | 5 ++++-
include/linux/vm_event_item.h | 1 +
mm/memcontrol.c | 2 ++
mm/oom_kill.c | 5 +++++
mm/vmstat.c | 1 +
6 files changed, 29 insertions(+), 5 deletions(-)
diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
index dc5e2dcdbef4..738b1c7023ad 100644
--- a/Documentation/cgroup-v2.txt
+++ b/Documentation/cgroup-v2.txt
@@ -826,13 +826,25 @@ 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
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 899949bbb2f9..42296f7001da 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -556,8 +556,11 @@ static inline void mem_cgroup_count_vm_event(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
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index d84ae90ccd5c..1707e0a7d943 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -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,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 94172089f52f..7011ebf2b90e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3574,6 +3574,7 @@ 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;
}
@@ -5165,6 +5166,7 @@ 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;
}
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 04c9143a8625..dd30a045ef5b 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -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: reaper must see this */
+ count_vm_event(OOM_KILL);
+ mem_cgroup_count_vm_event(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 76f73670200a..fe80b81a86e0 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1018,6 +1018,7 @@ const char * const vmstat_text[] = {
"drop_pagecache",
"drop_slab",
+ "oom_kill",
#ifdef CONFIG_NUMA_BALANCING
"numa_pte_updates",
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