linux-kernel - Re: [PATCH] mm/page_alloc: try oom if reclaim is unable to make forward progress

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Message-ID: <20210519130609.r3ml6ohb2qsrfq2t@ava.usersys.com>
Date:   Wed, 19 May 2021 14:06:09 +0100
From:   Aaron Tomlin <atomlin@...hat.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     linux-mm@...ck.org, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org, Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [PATCH] mm/page_alloc: try oom if reclaim is unable to make
 forward progress

Michal,

On Wed 2021-05-19 13:10 +0200, Michal Hocko wrote:
> > 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.

Understood.

I will post a trivial patch to hopefully address this particular condition
in the compaction retry code path, shortly for further discussion.


Kind regards,

-- 
Aaron Tomlin