linux-kernel - Re: [PATCH V3 3/3] mm: page_alloc: drain pcp lists before oom kill

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Message-ID: <342a8854-eef5-f68a-15e5-275de70e3f01@quicinc.com>
Date:   Tue, 14 Nov 2023 22:06:45 +0530
From:   Charan Teja Kalla <quic_charante@...cinc.com>
To:     Michal Hocko <mhocko@...e.com>
CC:     <akpm@...ux-foundation.org>, <mgorman@...hsingularity.net>,
        <david@...hat.com>, <vbabka@...e.cz>, <hannes@...xchg.org>,
        <quic_pkondeti@...cinc.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3 3/3] mm: page_alloc: drain pcp lists before oom kill

Thanks Michal!!

On 11/14/2023 4:18 PM, Michal Hocko wrote:
>> At least in my particular stress test case it just delayed the OOM as i
>> can see that at the time of OOM kill, there are no free pcp pages. My
>> understanding of the OOM is that it should be the last resort and only
>> after doing the enough reclaim retries. CMIW here.
> Yes it is a last resort but it is a heuristic as well. So the real
> questoin is whether this makes any practical difference outside of
> artificial workloads. I do not see anything particularly worrying to
> drain the pcp cache but it should be noted that this won't be 100%
> either as racing freeing of memory will end up on pcp lists first.

Okay, I don't have any practical scenario where this helped me in
avoiding the OOM.  Will comeback If I ever encounter this issue in
practical scenario.

Also If you have any comments on [PATCH V2 2/3] mm: page_alloc: correct
high atomic reserve calculations will help me.

Thanks.