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From: Aaron Tomlin <atomlin@redhat.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@suse.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/page_alloc: bail out on fatal signal during reclaim/compaction retry attempt
Date: Wed, 19 May 2021 20:08:01 +0100	[thread overview]
Message-ID: <20210519190801.t7fqdtixqmobqsps@ava.usersys.com> (raw)
In-Reply-To: <076e1c68-b4a2-26ea-9538-d88e6da800cc@suse.cz>

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On Wed 2021-05-19 17:22 +0200, Vlastimil Babka wrote:
> Hm, indeed, if fatal_signal_pending() is true then try_to_compact_pages() will
> bail out in the for-each-zone loop after trying a single zone and if that zone
> keeps returning COMPACT_SKIPPED, things can get stuck.
> And direct reclaim might see compaction_ready() for another zone and return 1,
> faking the progress.

Indeed.

> So your patch seems to be solving the issue. But maybe we should just do the
> test at the beginning of should_compact_retry() and not specific to
> compaction_needs_reclaim() - if there's a fatal signal, there will be no
> compaction happening, so we should just say not to retry.

Fair enough - I will post a v2.

> I suppose if the patch fixes your situation where fatal_signal_pending() was
> true, there's hopefully not a more general problem with the retry logic?

At the present time, not to my knowledge. That being said, I will continue
to review the relevant source code further.



Kind regards,

-- 
Aaron Tomlin

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      reply	other threads:[~2021-05-19 19:08 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
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 [this message]

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