From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Andreas Gruenbacher" <agruenba@redhat.com>,
"Christian Brauner" <brauner@kernel.org>,
"Darrick J. Wong" <djwong@kernel.org>,
gfs2 <gfs2@lists.linux.dev>,
linux-xfs@vger.kernel.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>, "Tejun Heo" <tj@kernel.org>,
"Johannes Weiner" <hannes@cmpxchg.org>,
"Michal Koutný" <mkoutny@suse.com>,
cgroups@vger.kernel.org, "Michal Hocko" <mhocko@kernel.org>,
"Roman Gushchin" <roman.gushchin@linux.dev>,
"Shakeel Butt" <shakeel.butt@linux.dev>,
"Muchun Song" <muchun.song@linux.dev>,
linux-mm@kvack.org
Subject: Re: iomap_writepages WARN_ON_ONCE(PF_MEMALLOC)
Date: Sat, 4 Jul 2026 01:56:58 +0100 [thread overview]
Message-ID: <akhaWrUHXcubQQab@casper.infradead.org> (raw)
In-Reply-To: <akZEjH2Hf8-RR8yQ@infradead.org>
On Thu, Jul 02, 2026 at 03:59:24AM -0700, Christoph Hellwig wrote:
> On Wed, Jul 01, 2026 at 10:51:06PM +0200, Andreas Gruenbacher wrote:
> > Do you have any suggestions?
> >
> > The above is on RHEL-8, but a similar code path exists in cgroups v2,
> > triggered via:
> >
> > echo reclaim_amount > /sys/fs/cgroup/.../memory.reclaim
> >
> > That code path starts with:
> >
> > memory_reclaim -> user_proactive_reclaim -> try_to_free_mem_cgroup_pages ->
>
> PF_MEMALLOC is a sign of direct reclaim. cgroup code is doing really
> weird things when it is set and it is doing writeback.
If we're going to blame the cgroup people for doing weird things, let's
cc them so they stand a chance of seeing this ... original at:
https://lore.kernel.org/linux-fsdevel/CAHc6FU4tz8-HmEf2_XKT0NT8N=rv5OMcY79PxTACkXAVLOAUpg@mail.gmail.com/
next prev parent reply other threads:[~2026-07-04 0:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-01 20:51 iomap_writepages WARN_ON_ONCE(PF_MEMALLOC) Andreas Gruenbacher
2026-07-02 10:59 ` Christoph Hellwig
2026-07-04 0:56 ` Matthew Wilcox [this message]
2026-07-06 13:15 ` Andreas Gruenbacher
2026-07-04 4:40 ` Shakeel Butt
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