On Thu 25-05-17 13:28:30, Konstantin Khlebnikov wrote:
> 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.
Yes this is less than optimal and the counter sounds like a good step
forward. I have 2 comments to the patch though.
[...]
> 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();
Well, this is ugly. I see how you want to share the global counter and
the memcg event which needs the notification. But I cannot say this
would be really easy to follow. Can we have at least a comment in
memcg_event_item enum definition?
> 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
Why don't you count tasks which share mm with the oom victim?
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 0e2c925e7826..9a95947a60ba 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -924,6 +924,8 @@ static void oom_kill_process(struct oom_control *oc, const
char *message)
*/
if (unlikely(p->flags & PF_KTHREAD))
continue;
+ count_vm_event(OOM_KILL);
+ count_memcg_event_mm(mm, OOM_KILL);
do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
}
rcu_read_unlock();
Other than that looks good to me.
Acked-by: Michal Hocko <[email protected]>
--
Michal Hocko
SUSE Labs
