linux-kernel - Re: [PATCH] mm: memcg: Don't periodically flush stats when memcg is disabled

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Message-ID: <CALvZod5_vZJFc0i0nGuEj3xt=9p9Jny682LRyb5oQpHvVk_ewg@mail.gmail.com>
Date: Fri, 26 Jan 2024 13:02:22 -0800
From: Shakeel Butt <shakeelb@...gle.com>
To: "T.J. Mercier" <tjmercier@...gle.com>
Cc: Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>, 
	Roman Gushchin <roman.gushchin@...ux.dev>, Muchun Song <muchun.song@...ux.dev>, 
	Andrew Morton <akpm@...ux-foundation.org>, android-mm@...gle.com, 
	Minchan Kim <minchan@...gle.com>, cgroups@...r.kernel.org, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: memcg: Don't periodically flush stats when memcg is disabled

On Fri, Jan 26, 2024 at 12:34 PM T.J. Mercier <tjmercier@...gle.com> wrote:
>
> The root memcg is onlined even when memcg is disabled. When it's onlined
> a 2 second periodic stat flush is started, but no stat flushing is
> required when memcg is disabled because there can be no child memcgs.
> Most calls to flush memcg stats are avoided when memcg is disabled as a
> result of the mem_cgroup_disabled check [1] added in [2], but the

Remove [1] reference and instead of [2] add the actual commit reference.

> periodic flushing started in mem_cgroup_css_online is not. Skip it.
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/memcontrol.c?h=v6.8-rc1#n753
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7d7ef0a4686abe43cd76a141b340a348f45ecdf2
>
> Fixes: aa48e47e3906 ("memcg: infrastructure to flush memcg stats")
> Reported-by: Minchan Kim <minchan@...gle.com>
> Signed-off-by: T.J. Mercier <tjmercier@...gle.com>

Acked-by: Shakeel Butt <shakeelb@...gle.com>