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 <[email protected]> --- 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",
