linux-kernel - Re: [RFC PATCH 6/7] memcg: objcg stock trylock without irq disabling

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Message-ID: <44489dcf-2bb1-45f3-a593-ac34da3f9138@suse.cz>
Date: Tue, 13 May 2025 15:05:24 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Shakeel Butt <shakeel.butt@...ux.dev>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>,
 Roman Gushchin <roman.gushchin@...ux.dev>,
 Muchun Song <muchun.song@...ux.dev>, Alexei Starovoitov <ast@...nel.org>,
 Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 Harry Yoo <harry.yoo@...cle.com>, Yosry Ahmed <yosry.ahmed@...ux.dev>,
 bpf@...r.kernel.org, linux-mm@...ck.org, cgroups@...r.kernel.org,
 linux-kernel@...r.kernel.org, Meta kernel team <kernel-team@...a.com>
Subject: Re: [RFC PATCH 6/7] memcg: objcg stock trylock without irq disabling

On 5/13/25 05:13, Shakeel Butt wrote:
> There is no need to disable irqs to use objcg per-cpu stock, so let's
> just not do that but consume_obj_stock() and refill_obj_stock() will
> need to use trylock instead to keep per-cpu stock safe. One consequence

I'd rather say "to avoid deadlock".

> of this change is that the charge request from irq context may take
> slowpath more often but it should be rare.
> 
> Signed-off-by: Shakeel Butt <shakeel.butt@...ux.dev>

Acked-by: Vlastimil Babka <vbabka@...e.cz>