From: Rik van Riel <riel@surriel.com>
To: Michal Hocko <mhocko@suse.com>
Cc: linux-kernel@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shakeel Butt <shakeel.butt@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
kernel-team@meta.com, stable@vger.kernel.org
Subject: Re: [PATCH] mm/memcontrol: avoid stuck FLUSHING_CACHED_CHARGE bit on isolated cpus
Date: Fri, 28 Aug 2026 10:56:17 -0400 [thread overview]
Message-ID: <34c252862494db8432c702efec4543daa11ff392.camel@surriel.com> (raw)
In-Reply-To: <apGaZdxAPH68kkCc@tiehlicka>
On Fri, 2026-08-28 at 16:25 +0200, Michal Hocko wrote:
> On Fri 28-08-26 09:46:21, Rik van Riel wrote:
> > drain_all_stock() can leave FLUSHING_CACHED_CHARGE set after the
> > work is dropped. It sets the bit before checking isolation and
> > schedule_drain_work() checks isolation and queues in a separate RCU
> > critical section, so housekeeping_update()'s synchronize_rcu() can
> > race the second check.
> >
> > drain_local_stock() only clears the bit for work that ran, so the
> > bit
> > remains set and the stock is never drained again.
> >
> > Reorganize the drain_all_stock() loop, reducing nesting, splitting
> > out local vs remote cpu handling, and skipping everything on
> > isolated
> > cpus, which solves the stuck FLUSHING_CACHED_CHARGE flag.
>
> Is there any reason why we cannot simply clear the flag if the work
> is
> not scheduled?
>
That should work, too.
I'm fine with whatever variant people prefer.
--
All Rights Reversed.
next prev parent reply other threads:[~2026-08-28 14:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-28 13:46 [PATCH 0/2] mm/memcontrol: fix stuck FLUSHING_CACHED_CHARGE bit on isolated cpus Rik van Riel
2026-08-28 13:46 ` [PATCH] mm/memcontrol: extract stock drain predicates into helpers Rik van Riel
2026-08-28 13:46 ` [PATCH] mm/memcontrol: avoid stuck FLUSHING_CACHED_CHARGE bit on isolated cpus Rik van Riel
2026-08-28 14:25 ` Michal Hocko
2026-08-28 14:56 ` Rik van Riel [this message]
2026-08-28 15:41 ` Shakeel Butt
2026-08-28 16:13 ` Rik van Riel
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