From: Michal Hocko <mhocko@suse.com>
To: Aaron Tomlin <atomlin@redhat.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org, Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH] mm/page_alloc: try oom if reclaim is unable to make forward progress
Date: Wed, 19 May 2021 13:10:33 +0200 [thread overview]
Message-ID: <YKTyKSDrFZjCS6Wu@dhcp22.suse.cz> (raw)
In-Reply-To: <20210518140554.dwan66i4ttmzw4hj@ava.usersys.com>
On Tue 18-05-21 15:05:54, Aaron Tomlin wrote:
> Michal,
>
> On Fri 2021-03-26 16:36 +0100, Michal Hocko wrote:
> > OK, I kinda expected this would be not easily reproducible.
>
> Unfortunately, I'm still waiting for feedback on this.
>
> > We should be focusing on the compaction retry logic and see whether we
> > can have some "run away" scenarios there. Seeing so many retries without
> > compaction bailing out sounds like a bug in that retry logic.
>
> I suspect so.
>
> This is indeed a case of excessive reclaim/compaction retries (i.e. the
> last known value stored in the no_progress_loops variable was 31,611,688).
>
> What might be particularly unique about this situation is that a fatal
> signal was found pending. In this context, if I understand correctly, it
> does not make sense to retry compaction when the last known compact result
> was skipped and a fatal signal is pending.
OK, this might be an interesting lead.
> Looking at try_to_compact_pages(), indeed COMPACT_SKIPPED can be returned;
> albeit, not every zone, on the zone list, would be considered in the case
> a fatal signal is found to be pending. Yet, in should_compact_retry(),
> given the last known compaction result, each zone, on the zone list, can be
> considered/or checked (see compaction_zonelist_suitable()). If a zone e.g.
> was found to succeed then reclaim/compaction would be tried again
> (notwithstanding the above).
I believe Vlastimil would be much better fit into looking into those
details but it smells like pending fatal signals can lead to a unbound
retry indeed.
Thanks!
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-05-19 11:10 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 16:58 [PATCH] mm/page_alloc: try oom if reclaim is unable to make forward progress Aaron Tomlin
2021-03-15 19:54 ` kernel test robot
2021-03-15 19:54 ` kernel test robot
2021-03-15 19:54 ` kernel test robot
2021-03-18 16:16 ` Michal Hocko
2021-03-19 17:29 ` Aaron Tomlin
2021-03-22 10:47 ` Michal Hocko
2021-03-25 21:01 ` Aaron Tomlin
2021-03-26 8:16 ` Michal Hocko
2021-03-26 11:22 ` Aaron Tomlin
2021-03-26 15:36 ` Michal Hocko
2021-03-26 17:00 ` Aaron Tomlin
2021-05-18 14:05 ` Aaron Tomlin
2021-05-19 11:10 ` Michal Hocko [this message]
2021-05-19 13:06 ` Aaron Tomlin
2021-05-19 14:50 ` [PATCH] mm/page_alloc: bail out on fatal signal during reclaim/compaction retry attempt Aaron Tomlin
2021-05-19 15:22 ` Vlastimil Babka
2021-05-19 19:08 ` Aaron Tomlin
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