On Wed 16-03-16 19:35:27, Tetsuo Handa wrote:
> "oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task" tried
> to protect oom_reaper_list using MMF_OOM_KILLED flag. But we can do it
> by simply checking tsk->oom_reaper_list != NULL.
I thought you would go with a replacement of the original patch but an
incremental one is also OK. Thanks this looks much more simpler
One could wonder why we do not have to check for oom_reaper_list under
the spinlock but this is not needed because the context calling
wake_oom_reaper is already synchronized.
> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Thanks!
> ---
> include/linux/sched.h | 2 --
> mm/oom_kill.c | 8 ++------
> 2 files changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 888bc15..e4dc0c9 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -512,8 +512,6 @@ static inline int get_dumpable(struct mm_struct *mm)
> #define MMF_HAS_UPROBES 19 /* has uprobes */
> #define MMF_RECALC_UPROBES 20 /* MMF_HAS_UPROBES can be wrong */
>
> -#define MMF_OOM_KILLED 21 /* OOM killer has chosen this mm */
> -
> #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
>
> struct sighand_struct {
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 23b8b06..31bbdc6 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -543,7 +543,7 @@ static int oom_reaper(void *unused)
>
> static void wake_oom_reaper(struct task_struct *tsk)
> {
> - if (!oom_reaper_th)
> + if (!oom_reaper_th || tsk->oom_reaper_list)
> return;
>
> get_task_struct(tsk);
> @@ -677,7 +677,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
> unsigned int victim_points = 0;
> static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
> DEFAULT_RATELIMIT_BURST);
> - bool can_oom_reap;
> + bool can_oom_reap = true;
>
> /*
> * If the task is already exiting, don't alarm the sysadmin or kill
> @@ -739,10 +739,6 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
> /* Get a reference to safely compare mm after task_unlock(victim) */
> mm = victim->mm;
> atomic_inc(&mm->mm_count);
> -
> - /* Make sure we do not try to oom reap the mm multiple times */
> - can_oom_reap = !test_and_set_bit(MMF_OOM_KILLED, &mm->flags);
> -
> /*
> * We should send SIGKILL before setting TIF_MEMDIE in order to prevent
> * the OOM victim from depleting the memory reserves from the user
> --
> 1.8.3.1
>
--
Michal Hocko
SUSE Labs
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