From: Andrew Morton <akpm@linux-foundation.org>
To: Rik van Riel <riel@surriel.com>
Cc: linux-kernel@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeel.butt@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
kernel-team@meta.com
Subject: Re: [PATCH v2] mm/memcontrol: fix stuck FLUSHING_CACHED_CHARGE bit on isolated cpus
Date: Fri, 28 Aug 2026 12:20:18 -0700 [thread overview]
Message-ID: <20260828122018.1a3b3be204212837fcda8e50@linux-foundation.org> (raw)
In-Reply-To: <20260828135036.7d44361f@fangorn>
On Fri, 28 Aug 2026 13:50:36 -0400 Rik van Riel <riel@surriel.com> wrote:
> When drain_all_stock() sets FLUSHING_CACHED_CHARGE before checking
> isolation, schedule_drain_work() can drop the work in a separate RCU
> critical section, and housekeeping_update()'s synchronize_rcu() can race
> that second check, leaving the flag set.
>
> drain_local_stock() only clears the bit for work that ran, so the flag
> remains set and the stock is never drained again.
>
> Have schedule_drain_work() return whether the work was queued, and clear
> FLUSHING_CACHED_CHARGE in drain_all_stock() when the remote CPU is
> isolated, so future drains can retry.
Is there some Reported-by: or reproducer for this?
Given the complexity of the reproducers which Gemini developed for me, I'm
suspecting "nope".
> Fixes: 6a792697a53a ("memcg: do not drain charge pcp caches on remote isolated cpus")
> Cc: stable@vger.kernel.org
Why is a backport being proposed? How does that benefit those we
serve?
Sashiko suggests that we ain't done yet:
https://sashiko.dev/#/patchset/20260828135036.7d44361f@fangorn
next prev parent reply other threads:[~2026-08-28 19:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-28 17:50 [PATCH v2] mm/memcontrol: fix stuck FLUSHING_CACHED_CHARGE bit on isolated cpus Rik van Riel
2026-08-28 18:56 ` Shakeel Butt
2026-08-28 19:20 ` Andrew Morton [this message]
2026-08-28 19:26 ` Shakeel Butt
2026-08-28 19:55 ` Andrew Morton
2026-08-28 20:01 ` Rik van Riel
2026-08-31 7:29 ` Michal Hocko
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