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SubjectRe: [PATCH] mm/oom_kill: count global and memory cgroup oom kills
[CC Vladimir and Johannes as this involves memcg]

i will get to this early next week but from a quick look it seems
acceptable.

On Fri 19-05-17 17:22:30, Konstantin Khlebnikov wrote:
> Show count of global oom killer invocations in /proc/vmstat and
> count of oom kills inside 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@yandex-team.ru>
> ---
> Documentation/cgroup-v2.txt | 12 +++++++++++-
> include/linux/memcontrol.h | 1 +
> include/linux/vm_event_item.h | 1 +
> mm/memcontrol.c | 2 ++
> mm/oom_kill.c | 6 ++++++
> mm/vmstat.c | 1 +
> 6 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
> index dc5e2dcdbef4..a742008d76aa 100644
> --- a/Documentation/cgroup-v2.txt
> +++ b/Documentation/cgroup-v2.txt
> @@ -830,9 +830,19 @@ PAGE_SIZE multiple when read back.
>
> oom
>
> + The number of time the cgroup's memory usage was
> + reached the limit and allocation was about to fail.
> + Result could be oom kill, -ENOMEM from any syscall or
> + completely 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 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.
> + processes killed but should generally be close: each
> + invocation could kill several processes at once.
>
> memory.stat
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 899949bbb2f9..2cdcebb78b58 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -55,6 +55,7 @@ enum memcg_event_item {
> MEMCG_HIGH,
> MEMCG_MAX,
> MEMCG_OOM,
> + MEMCG_OOM_KILL,
> MEMCG_NR_EVENTS,
> };
>
> 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..416024837b81 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, 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, MEMCG_OOM_KILL));
>
> return 0;
> }
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 04c9143a8625..c50bff3c3409 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -873,6 +873,12 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
> victim = p;
> }
>
> + /* Raise event before sending signal: reaper must see this */
> + if (!is_memcg_oom(oc))
> + count_vm_event(OOM_KILL);
> + else
> + mem_cgroup_event(oc->memcg, MEMCG_OOM_KILL);
> +
> /* Get a reference to safely compare mm after task_unlock(victim) */
> mm = victim->mm;
> mmgrab(mm);
> 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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--
Michal Hocko
SUSE Labs

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