From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Michal Hocko <mhocko@kernel.org>, linux-mm@kvack.org
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH 1/2] mm, oom: marks all killed tasks as oom victims
Date: Tue, 8 Jan 2019 05:58:41 +0900 [thread overview]
Message-ID: <1054b5c6-19c0-53a4-206e-dd55f5a3d732@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20190107143802.16847-2-mhocko@kernel.org>
On 2019/01/07 23:38, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> Historically we have called mark_oom_victim only to the main task
> selected as the oom victim because oom victims have access to memory
> reserves and granting the access to all killed tasks could deplete
> memory reserves very quickly and cause even larger problems.
>
> Since only a partial access to memory reserves is allowed there is no
> longer this risk and so all tasks killed along with the oom victim
> can be considered as well.
>
> The primary motivation for that is that process groups which do not
> shared signals would behave more like standard thread groups wrt oom
> handling (aka tsk_is_oom_victim will work the same way for them).
>
> - Use find_lock_task_mm to stabilize mm as suggested by Tetsuo
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
> mm/oom_kill.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index f0e8cd9edb1a..0246c7a4e44e 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -892,6 +892,7 @@ static void __oom_kill_process(struct task_struct *victim)
> */
> rcu_read_lock();
> for_each_process(p) {
> + struct task_struct *t;
> if (!process_shares_mm(p, mm))
> continue;
> if (same_thread_group(p, victim))
> @@ -911,6 +912,11 @@ static void __oom_kill_process(struct task_struct *victim)
> if (unlikely(p->flags & PF_KTHREAD))
> continue;
> do_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_TGID);
> + t = find_lock_task_mm(p);
> + if (!t)
> + continue;
> + mark_oom_victim(t);
> + task_unlock(t);
Thank you for updating this patch. This patch is correct from the point of
view of avoiding TIF_MEMDIE race. But if I recall correctly, the reason we
did not do this is to avoid depleting memory reserves. And we still grant
full access to memory reserves for CONFIG_MMU=n case. Shouldn't the changelog
mention CONFIG_MMU=n case?
> }
> rcu_read_unlock();
>
>
next prev parent reply other threads:[~2019-01-07 20:59 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-07 14:38 [PATCH 0/2] oom, memcg: do not report racy no-eligible OOM Michal Hocko
2019-01-07 14:38 ` [PATCH 1/2] mm, oom: marks all killed tasks as oom victims Michal Hocko
2019-01-07 20:58 ` Tetsuo Handa [this message]
2019-01-08 8:11 ` Michal Hocko
2019-01-07 14:38 ` [PATCH 2/2] memcg: do not report racy no-eligible OOM tasks Michal Hocko
2019-01-07 20:59 ` Tetsuo Handa
2019-01-08 8:14 ` Michal Hocko
2019-01-08 10:39 ` Tetsuo Handa
2019-01-08 11:46 ` Michal Hocko
2019-01-08 8:35 ` kbuild test robot
2019-01-08 9:39 ` Michal Hocko
2019-01-11 0:23 ` [kbuild-all] " Rong Chen
2019-01-08 14:21 ` [PATCH 3/2] memcg: Facilitate termination of memcg OOM victims Tetsuo Handa
2019-01-08 14:38 ` Michal Hocko
2019-01-09 11:03 ` [PATCH 0/2] oom, memcg: do not report racy no-eligible OOM Michal Hocko
2019-01-09 11:34 ` Tetsuo Handa
2019-01-09 12:02 ` Michal Hocko
2019-01-10 23:59 ` Tetsuo Handa
2019-01-11 10:25 ` Tetsuo Handa
2019-01-11 11:33 ` Michal Hocko
2019-01-11 12:40 ` Tetsuo Handa
2019-01-11 13:34 ` Michal Hocko
2019-01-11 14:31 ` Tetsuo Handa
2019-01-11 15:07 ` Michal Hocko
2019-01-11 15:37 ` Tetsuo Handa
2019-01-11 16:45 ` Michal Hocko
2019-01-12 10:52 ` Tetsuo Handa
2019-01-13 17:36 ` Michal Hocko
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