From: Michal Hocko <mhocko@kernel.org>
To: Johannes Weiner <hannes@cmpxchg.org>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: linux-mm@kvack.org, David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 2/2] memcg: do not report racy no-eligible OOM tasks
Date: Wed, 7 Nov 2018 11:08:10 +0100 [thread overview]
Message-ID: <20181107100810.GA27423@dhcp22.suse.cz> (raw)
In-Reply-To: <8725e3b3-3752-fa7f-a88f-5ff4f5b6eace@i-love.sakura.ne.jp>
On Wed 07-11-18 18:45:27, Tetsuo Handa wrote:
> On 2018/11/06 21:42, Michal Hocko wrote:
> > On Tue 06-11-18 18:44:43, Tetsuo Handa wrote:
> > [...]
> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> >> index 6e1469b..a97648a 100644
> >> --- a/mm/memcontrol.c
> >> +++ b/mm/memcontrol.c
> >> @@ -1382,8 +1382,13 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
> >> };
> >> bool ret;
> >>
> >> - mutex_lock(&oom_lock);
> >> - ret = out_of_memory(&oc);
> >> + if (mutex_lock_killable(&oom_lock))
> >> + return true;
> >> + /*
> >> + * A few threads which were not waiting at mutex_lock_killable() can
> >> + * fail to bail out. Therefore, check again after holding oom_lock.
> >> + */
> >> + ret = fatal_signal_pending(current) || out_of_memory(&oc);
> >> mutex_unlock(&oom_lock);
> >> return ret;
> >> }
> >
> > If we are goging with a memcg specific thingy then I really prefer
> > tsk_is_oom_victim approach. Or is there any reason why this is not
> > suitable?
> >
>
> Why need to wait for mark_oom_victim() called after slow printk() messages?
>
> If current thread got Ctrl-C and thus current thread can terminate, what is
> nice with waiting for the OOM killer? If there are several OOM events in
> multiple memcg domains waiting for completion of printk() messages? I don't
> see points with waiting for oom_lock, for try_charge() already allows current
> thread to terminate due to fatal_signal_pending() test.
mutex_lock_killable would take care of exiting task already. I would
then still prefer to check for mark_oom_victim because that is not racy
with the exit path clearing signals. I can update my patch to use
_killable lock variant if we are really going with the memcg specific
fix.
Johaness?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-11-07 10:08 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-22 7:13 [RFC PATCH 0/2] oom, memcg: do not report racy no-eligible OOM Michal Hocko
2018-10-22 7:13 ` [RFC PATCH 1/2] mm, oom: marks all killed tasks as oom victims Michal Hocko
2018-10-22 7:58 ` Tetsuo Handa
2018-10-22 8:48 ` Michal Hocko
2018-10-22 9:42 ` Tetsuo Handa
2018-10-22 10:43 ` Michal Hocko
2018-10-22 10:56 ` Tetsuo Handa
2018-10-22 11:12 ` Michal Hocko
2018-10-22 11:16 ` [RFC PATCH v2 " Michal Hocko
2018-10-22 7:13 ` [RFC PATCH 2/2] memcg: do not report racy no-eligible OOM tasks Michal Hocko
2018-10-22 11:45 ` Tetsuo Handa
2018-10-22 12:03 ` Michal Hocko
2018-10-22 13:20 ` Tetsuo Handa
2018-10-22 13:43 ` Michal Hocko
2018-10-22 15:12 ` Tetsuo Handa
2018-10-23 1:01 ` Tetsuo Handa
2018-10-23 11:42 ` Michal Hocko
2018-10-23 12:10 ` Michal Hocko
2018-10-23 12:33 ` Tetsuo Handa
2018-10-23 12:48 ` Michal Hocko
2018-10-26 14:25 ` Johannes Weiner
2018-10-26 19:25 ` Michal Hocko
2018-10-26 19:33 ` Michal Hocko
2018-10-27 1:10 ` Tetsuo Handa
2018-11-06 9:44 ` Tetsuo Handa
2018-11-06 12:42 ` Michal Hocko
2018-11-07 9:45 ` Tetsuo Handa
2018-11-07 10:08 ` Michal Hocko [this message]
2018-12-07 12:43 ` Tetsuo Handa
2018-12-12 10:23 ` Tetsuo Handa
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