From: Michal Hocko <mhocko@kernel.org>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Greg Thelen <gthelen@google.com>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Dmitry Vyukov <dvyukov@google.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] memcg, oom: be careful about races when warning about no reclaimable task
Date: Wed, 8 Aug 2018 09:12:59 +0200 [thread overview]
Message-ID: <20180808071301.12478-1-mhocko@kernel.org> (raw)
In-Reply-To: <20180808064414.GA27972@dhcp22.suse.cz>
On Wed 08-08-18 08:44:14, Michal Hocko wrote:
> On Tue 07-08-18 16:54:25, Johannes Weiner wrote:
[...]
> > What the global OOM killer does in that situation is dump the header
> > anyway:
> >
> > /* Found nothing?!?! Either we hang forever, or we panic. */
> > if (!oc->chosen && !is_sysrq_oom(oc) && !is_memcg_oom(oc)) {
> > dump_header(oc, NULL);
> > panic("Out of memory and no killable processes...\n");
> > }
> >
> > I think that would make sense here as well - without the panic,
> > obviously, but we can add our own pr_err() line following the header.
> >
> > That gives us the exact memory situation of the cgroup and who is
> > trying to allocate and from what context, but in a format that is
> > known to users without claiming right away that it's a kernel issue.
>
> I was considering doing that initially but then decided that warning is
> less noisy and still a good "let us know" trigger. It doesn't give us
> the whole picture which is obviously a downside but we would at least
> know that something is going south one have the trace to who that might
> be should this be a bug rather than a misconfiguration.
>
> But I do not mind doing dump_header as well. Care to send a patch?
OK, so I found few spare cycles and here is what I came up with. The
first patch fixes the spurious warning and I have separated the check
and added a comment as you asked. The second patch replaces warning with
oom report.
Does that look better?
next prev parent reply other threads:[~2018-08-08 7:13 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-07 7:25 [PATCH] memcg, oom: be careful about races when warning about no reclaimable task Michal Hocko
2018-08-07 10:15 ` Tetsuo Handa
2018-08-07 11:04 ` Michal Hocko
2018-08-07 20:19 ` Johannes Weiner
2018-08-07 20:38 ` Tetsuo Handa
2018-08-08 12:57 ` Tetsuo Handa
2018-08-08 13:16 ` Michal Hocko
2018-08-07 20:02 ` Johannes Weiner
2018-08-07 20:23 ` Michal Hocko
2018-08-07 20:54 ` Johannes Weiner
2018-08-08 6:44 ` Michal Hocko
2018-08-08 7:12 ` Michal Hocko [this message]
2018-08-08 7:13 ` [PATCH 1/2] " Michal Hocko
2018-08-08 7:13 ` [PATCH 2/2] memcg, oom: emit oom report when there is no eligible task Michal Hocko
2018-08-08 14:45 ` Johannes Weiner
2018-08-08 16:17 ` Michal Hocko
2018-08-21 14:06 ` Michal Hocko
2018-08-21 17:20 ` Johannes Weiner
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