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

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Date: Mon, 29 Jan 2024 16:04:28 +0100
From: Michal Hocko <mhocko@...e.com>
To: Zach O'Keefe <zokeefe@...gle.com>
Cc: Charan Teja Kalla <quic_charante@...cinc.com>,
	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,
	Axel Rasmussen <axelrasmussen@...gle.com>,
	Yosry Ahmed <yosryahmed@...gle.com>,
	David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH V3 3/3] mm: page_alloc: drain pcp lists before oom kill

On Fri 26-01-24 14:51:26, Zach O'Keefe wrote:
[...]
> Node 0 DMA32 free:66592kB min:2580kB low:5220kB high:7860kB
[...]
> free_pcp:8040kB local_pcp:244kB free_cma:0kB
> lowmem_reserve[]: 0 0 16029 16029
> Node 0 Normal free:513048kB min:513192kB low:1038700kB high:1564208kB
[...]
> mlocked:12344kB bounce:0kB free_pcp:790040kB local_pcp:7060kB
[...]
> mlocked:1588kB bounce:0kB free_pcp:253500kB local_pcp:12kB
[...]
> I'm not familiar with these changes, but a quick check of recent
> activity points to v6.7 commit fa8c4f9a665b ("mm: fix draining remote
> pageset") ; is this what you are referring to?

No, but looking at above discrepancy between free_pcp and local_pcp
would point that direction for sure. So this is worth checking.
vmstat is a periodic activity and it cannot really deal with bursts
of memory allocations but it is quite possible that the patch above
will prevent the build up before it grows that large.

I originally referred to different work though https://lore.kernel.org/all/20231016053002.756205-10-ying.huang@intel.com/T/#m9fdfabaee37db1320bbc678a69d1cdd8391640e0
merged as ca71fe1ad922 ("mm, pcp: avoid to drain PCP when process exit")
and the associated patches.

-- 
Michal Hocko
SUSE Labs