From: Michal Hocko <mhocko@kernel.org>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: akpm@linux-foundation.org, rientjes@google.com, mgorman@suse.de,
oleg@redhat.com, torvalds@linux-foundation.org, hughd@google.com,
andrea@kernel.org, riel@redhat.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/5] mm, oom_reaper: implement OOM victims queuing
Date: Tue, 16 Feb 2016 16:53:22 +0100 [thread overview]
Message-ID: <20160216155322.GC23437@dhcp22.suse.cz> (raw)
In-Reply-To: <201602162011.ECG52697.VOLJFtOQHFMSFO@I-love.SAKURA.ne.jp>
On Tue 16-02-16 20:11:24, Tetsuo Handa wrote:
> Michal Hocko wrote:
> > Unless we are under global OOM then this doesn't matter much because the
> > allocation request should succeed at some point in time and memcg
> > charges are bypassed for tasks with pending fatal signals. So we can
> > make a forward progress.
>
> Hmm, then I wonder how memcg OOM livelock occurs. Anyway, OK for now.
>
> But current OOM reaper forgot a protection for list item "double add" bug.
> Precisely speaking, this is not a OOM reaper's bug.
[...]
> For oom_kill_allocating_task = 1 case (despite the name, it still tries to kill
> children first),
Yes this is a long term behavior and I cannot say I would be happy about
that because it clearly breaks the defined semantic.
> the OOM killer does not wait for OOM victim to clear TIF_MEMDIE
> because select_bad_process() is not called. Therefore, if an OOM victim fails to
> terminate because the OOM reaper failed to reap enough memory, the kernel is
> flooded with OOM killer messages trying to kill that stuck victim (with OOM
> reaper lockup due to list corruption).
Hmmm, I didn't consider this possibility. For now I would simply disable
oom_reaper for sysctl_oom_kill_allocating_task. oom_kill_allocating_task
needs some more changes IMO. a) we shouldn't kill children as a
heuristic b) we should go and panic if the current task is TIF_MEMDIE
already because that means that we cannot do anything about OOM. But I
think this should be handled separately.
Whould be the following acceptable for now?
---
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 7e9953a64489..357cee067950 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -678,7 +678,14 @@ 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 = true;
+ bool can_oom_reap;
+
+ /*
+ * oom_kill_allocating_task doesn't follow normal OOM exclusion
+ * and so the same task might enter oom_kill_process which oom_reaper
+ * cannot handle currently.
+ */
+ can_oom_reap = !sysctl_oom_kill_allocating_task;
/*
* If the task is already exiting, don't alarm the sysadmin or kill
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2016-02-16 15:53 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-03 13:13 [PATCH 0/5] oom reaper v5 Michal Hocko
2016-02-03 13:13 ` [PATCH 1/5] mm, oom: introduce oom reaper Michal Hocko
2016-02-03 23:48 ` David Rientjes
2016-02-04 6:41 ` Michal Hocko
2016-02-06 13:22 ` Tetsuo Handa
2016-02-15 20:50 ` Michal Hocko
2016-02-03 13:13 ` [PATCH 2/5] oom reaper: handle mlocked pages Michal Hocko
2016-02-03 23:57 ` David Rientjes
2016-02-23 1:36 ` David Rientjes
2016-02-23 13:21 ` Michal Hocko
2016-02-29 3:19 ` Hugh Dickins
2016-02-29 13:41 ` Michal Hocko
2016-03-08 13:40 ` Michal Hocko
2016-03-08 20:07 ` Hugh Dickins
2016-03-09 8:26 ` Michal Hocko
2016-02-03 13:13 ` [PATCH 3/5] oom: clear TIF_MEMDIE after oom_reaper managed to unmap the address space Michal Hocko
2016-02-04 14:22 ` Tetsuo Handa
2016-02-04 14:43 ` Michal Hocko
2016-02-04 15:08 ` Tetsuo Handa
2016-02-04 16:31 ` Michal Hocko
2016-02-05 11:14 ` Tetsuo Handa
2016-02-06 8:30 ` Michal Hocko
2016-02-06 11:23 ` Tetsuo Handa
2016-02-15 20:47 ` Michal Hocko
2016-02-06 6:45 ` Michal Hocko
2016-02-06 14:33 ` Tetsuo Handa
2016-02-15 20:40 ` [PATCH 3.1/5] oom: make oom_reaper freezable Michal Hocko
2016-02-03 13:13 ` [PATCH 4/5] mm, oom_reaper: report success/failure Michal Hocko
2016-02-03 23:10 ` David Rientjes
2016-02-04 6:46 ` Michal Hocko
2016-02-04 22:31 ` David Rientjes
2016-02-05 9:26 ` Michal Hocko
2016-02-06 6:34 ` Michal Hocko
2016-02-03 13:14 ` [PATCH 5/5] mm, oom_reaper: implement OOM victims queuing Michal Hocko
2016-02-04 10:49 ` Tetsuo Handa
2016-02-04 14:53 ` Michal Hocko
2016-02-06 5:54 ` Tetsuo Handa
2016-02-06 8:37 ` Michal Hocko
2016-02-06 15:33 ` Tetsuo Handa
2016-02-15 20:15 ` Michal Hocko
2016-02-16 11:11 ` Tetsuo Handa
2016-02-16 15:53 ` Michal Hocko [this message]
2016-02-17 9:48 ` [PATCH 6/5] oom, oom_reaper: disable oom_reaper for Michal Hocko
2016-02-17 10:41 ` Tetsuo Handa
2016-02-17 11:33 ` Michal Hocko
2016-02-19 18:34 ` Michal Hocko
2016-02-20 2:32 ` [PATCH 6/5] oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task Tetsuo Handa
2016-02-22 9:41 ` Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160216155322.GC23437@dhcp22.suse.cz \
--to=mhocko@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=andrea@kernel.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=oleg@redhat.com \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=riel@redhat.com \
--cc=rientjes@google.com \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).