From: Michal Hocko <mhocko@kernel.org> To: <linux-mm@kvack.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, David Rientjes <rientjes@google.com>, Oleg Nesterov <oleg@redhat.com>, Vladimir Davydov <vdavydov@parallels.com>, Andrew Morton <akpm@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, Michal Hocko <mhocko@suse.com> Subject: [PATCH 06/10] mm, oom: kill all tasks sharing the mm Date: Mon, 20 Jun 2016 14:43:44 +0200 [thread overview] Message-ID: <1466426628-15074-7-git-send-email-mhocko@kernel.org> (raw) In-Reply-To: <1466426628-15074-1-git-send-email-mhocko@kernel.org> From: Michal Hocko <mhocko@suse.com> Currently oom_kill_process skips both the oom reaper and SIG_KILL if a process sharing the same mm is unkillable via OOM_ADJUST_MIN. After "mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj" all such processes are sharing the same value so we shouldn't see such a task at all (oom_badness would rule them out). We can still encounter oom disabled vforked task which has to be killed as well if we want to have other tasks sharing the mm reapable because it can access the memory before doing exec. Killing such a task should be acceptable because it is highly unlikely it has done anything useful because it cannot modify any memory before it calls exec. An alternative would be to keep the task alive and skip the oom reaper and risk all the weird corner cases where the OOM killer cannot make forward progress because the oom victim hung somewhere on the way to exit. [rientjes@google.com - drop printk when OOM_SCORE_ADJ_MIN killed task the setting is inherently racy and we cannot do much about it without introducing locks in hot paths] Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Michal Hocko <mhocko@suse.com> --- mm/oom_kill.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 02da660b7c25..38f89ac2df7f 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -852,8 +852,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, continue; if (same_thread_group(p, victim)) continue; - if (unlikely(p->flags & PF_KTHREAD) || is_global_init(p) || - p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { + if (unlikely(p->flags & PF_KTHREAD) || is_global_init(p)) { /* * We cannot use oom_reaper for the mm shared by this * process because it wouldn't get killed and so the -- 2.8.1
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: linux-mm@kvack.org Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, David Rientjes <rientjes@google.com>, Oleg Nesterov <oleg@redhat.com>, Vladimir Davydov <vdavydov@parallels.com>, Andrew Morton <akpm@linux-foundation.org>, LKML <linux-kernel@vger.kernel.org>, Michal Hocko <mhocko@suse.com> Subject: [PATCH 06/10] mm, oom: kill all tasks sharing the mm Date: Mon, 20 Jun 2016 14:43:44 +0200 [thread overview] Message-ID: <1466426628-15074-7-git-send-email-mhocko@kernel.org> (raw) In-Reply-To: <1466426628-15074-1-git-send-email-mhocko@kernel.org> From: Michal Hocko <mhocko@suse.com> Currently oom_kill_process skips both the oom reaper and SIG_KILL if a process sharing the same mm is unkillable via OOM_ADJUST_MIN. After "mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj" all such processes are sharing the same value so we shouldn't see such a task at all (oom_badness would rule them out). We can still encounter oom disabled vforked task which has to be killed as well if we want to have other tasks sharing the mm reapable because it can access the memory before doing exec. Killing such a task should be acceptable because it is highly unlikely it has done anything useful because it cannot modify any memory before it calls exec. An alternative would be to keep the task alive and skip the oom reaper and risk all the weird corner cases where the OOM killer cannot make forward progress because the oom victim hung somewhere on the way to exit. [rientjes@google.com - drop printk when OOM_SCORE_ADJ_MIN killed task the setting is inherently racy and we cannot do much about it without introducing locks in hot paths] Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Michal Hocko <mhocko@suse.com> --- mm/oom_kill.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 02da660b7c25..38f89ac2df7f 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -852,8 +852,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, continue; if (same_thread_group(p, victim)) continue; - if (unlikely(p->flags & PF_KTHREAD) || is_global_init(p) || - p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { + if (unlikely(p->flags & PF_KTHREAD) || is_global_init(p)) { /* * We cannot use oom_reaper for the mm shared by this * process because it wouldn't get killed and so the -- 2.8.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-06-20 12:44 UTC|newest] Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-20 12:43 [PATCH 0/10 -v5] Handle oom bypass more gracefully Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-06-20 12:43 ` [PATCH 01/10] proc, oom: drop bogus task_lock and mm check Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-06-20 12:43 ` [PATCH 02/10] proc, oom: drop bogus sighand lock Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-06-20 12:43 ` [PATCH 03/10] proc, oom_adj: extract oom_score_adj setting into a helper Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-06-20 12:43 ` [PATCH 04/10] mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-06-20 12:43 ` [PATCH 05/10] mm, oom: skip vforked tasks from being selected Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-06-20 12:43 ` Michal Hocko [this message] 2016-06-20 12:43 ` [PATCH 06/10] mm, oom: kill all tasks sharing the mm Michal Hocko 2016-06-20 12:43 ` [PATCH 07/10] mm, oom: fortify task_will_free_mem Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-06-20 12:43 ` [PATCH 08/10] mm, oom: task_will_free_mem should skip oom_reaped tasks Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-06-20 12:43 ` [PATCH 09/10] mm, oom_reaper: do not attempt to reap a task more than twice Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-06-20 12:43 ` [PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init Michal Hocko 2016-06-20 12:43 ` Michal Hocko 2016-07-19 12:05 ` Michal Hocko 2016-07-19 12:05 ` Michal Hocko 2016-07-19 23:27 ` Andrew Morton 2016-07-19 23:27 ` Andrew Morton 2016-07-20 6:29 ` Michal Hocko 2016-07-20 6:29 ` Michal Hocko -- strict thread matches above, loose matches on Subject: below -- 2016-06-09 11:52 [PATCH 0/10 -v4] Handle oom bypass more gracefully Michal Hocko 2016-06-09 11:52 ` [PATCH 06/10] mm, oom: kill all tasks sharing the mm Michal Hocko 2016-06-09 11:52 ` Michal Hocko 2016-06-03 9:16 [PATCH 0/10 -v3] Handle oom bypass more gracefully Michal Hocko 2016-06-03 9:16 ` [PATCH 06/10] mm, oom: kill all tasks sharing the mm Michal Hocko 2016-06-03 9:16 ` Michal Hocko 2016-06-06 22:27 ` David Rientjes 2016-06-06 22:27 ` David Rientjes 2016-06-06 23:20 ` Oleg Nesterov 2016-06-06 23:20 ` Oleg Nesterov 2016-06-07 6:37 ` Michal Hocko 2016-06-07 6:37 ` Michal Hocko 2016-06-07 22:15 ` David Rientjes 2016-06-07 22:15 ` David Rientjes 2016-06-08 6:22 ` Michal Hocko 2016-06-08 6:22 ` Michal Hocko 2016-06-08 22:51 ` David Rientjes 2016-06-08 22:51 ` David Rientjes 2016-06-09 6:46 ` Michal Hocko 2016-06-09 6:46 ` Michal Hocko
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