linux-kernel - Re: [patch] mm, oom: stop reclaiming if GFP

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Message-ID: <bcf6d15f-cbdb-8c45-6087-a0f2aab737c6@i-love.sakura.ne.jp>
Date:   Wed, 29 Apr 2020 19:45:07 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Vlastimil Babka <vbabka@...e.cz>,
        David Rientjes <rientjes@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: Re: [patch] mm, oom: stop reclaiming if GFP_ATOMIC will start failing
 soon

On 2020/04/29 18:04, Michal Hocko wrote:
> Completely agreed! The in kernel OOM killer is to deal with situations
> when memory is desperately depleted without any sign of a forward
> progress. If there is a reclaimable memory then we are not there yet.
> If a workload can benefit from early oom killing based on response time
> then we have facilities to achieve that (e.g. PSI).

Can PSI work even if userspace process cannot avoid reclaimable memory
allocations (e.g. page fault, file read) is already stalling? I'm not sure
whether PSI allows responding quickly enough to "keep reclaimable memory
allocations not to reclaim" despite there is still reclaimable memory...