linux-kernel - Re: [PATCH 2/4] memcg: separate local

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Message-ID: <3d99da0d-b08e-416e-82bb-cd44179a424f@suse.cz>
Date: Wed, 7 May 2025 13:46:51 +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>,
 Jakub Kicinski <kuba@...nel.org>, Eric Dumazet <edumazet@...gle.com>,
 linux-mm@...ck.org, cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
 bpf@...r.kernel.org, netdev@...r.kernel.org,
 Meta kernel team <kernel-team@...a.com>
Subject: Re: [PATCH 2/4] memcg: separate local_trylock for memcg and obj

On 5/7/25 12:55 AM, Shakeel Butt wrote:
> The per-cpu stock_lock protects cached memcg and cached objcg and their
> respective fields. However there is no dependency between these fields
> and it is better to have fine grained separate locks for cached memcg
> and cached objcg. This decoupling of locks allows us to make the memcg
> charge cache and objcg charge cache to be nmi safe independently.
> 
> At the moment, memcg charge cache is already nmi safe and this
> decoupling will allow to make memcg charge cache work without disabling
> irqs.
> 
> Signed-off-by: Shakeel Butt <shakeel.butt@...ux.dev>

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