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b=Co2uEtQt0SYWN/uVQ8wieRC7EHb2o4A0t5p5W8viVE7GGxZJMu4laOwivRh0DqQnk gewQq4bFlkQa/k+pWap14rQjNpT3cK2mzTskebMAZswHXL5zsbOTylRg7rDJO9DoSu ve1ju0QIq0U2PPofuCoqgwp5qdylE8rnkPFuEewY= Date: Mon, 4 Nov 2024 13:38:34 -0800 From: Andrew Morton To: Yu Zhao Cc: Shakeel Butt , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Hugh Dickins , Yosry Ahmed , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, Meta kernel team Subject: Re: [PATCH v1 5/6] memcg-v1: no need for memcg locking for MGLRU Message-Id: <20241104133834.e0e138038a111c2b0d20bdde@linux-foundation.org> In-Reply-To: References: <20241025012304.2473312-1-shakeel.butt@linux.dev> <20241025012304.2473312-6-shakeel.butt@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 605101C0013 X-Rspamd-Server: rspam01 X-Stat-Signature: qqxgdr4rwfckue1qsfyoxpq45eqdk4qf X-HE-Tag: 1730756255-329719 X-HE-Meta: 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 sBmFU+hi vVRYo6okDswJyWcoeymjgL3NjajryelOEVYZ6TqnnxeSylj3ZMVLoe1tZ8GPatEp4b7x0mYCpvYtTd/q+tD8yxzBGl/G4z2avZGXJXToe66H4QvQH6tTJqU21ZucXe7NrINRmL16jvSsY+hi71EXN6e43wxupau3LHZLp5oqDn7U3w0euAFrMX89piouq6r2jUZsypiCJzUyl03VJagco10wIse7roSbWhj/Ex2eIuOwtzkT+LhE4Ad0dThLrd538NzNXOh5W3URYDwnROMK8L27bPfP9yAq7q8ptjFKu9fMDUoE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 4 Nov 2024 10:30:29 -0700 Yu Zhao wrote: > On Sat, Oct 26, 2024 at 09:26:04AM -0600, Yu Zhao wrote: > > On Sat, Oct 26, 2024 at 12:34 AM Shakeel Butt wrote: > > > > > > On Thu, Oct 24, 2024 at 06:23:02PM GMT, Shakeel Butt wrote: > > > > While updating the generation of the folios, MGLRU requires that the > > > > folio's memcg association remains stable. With the charge migration > > > > deprecated, there is no need for MGLRU to acquire locks to keep the > > > > folio and memcg association stable. > > > > > > > > Signed-off-by: Shakeel Butt > > > > > > Andrew, can you please apply the following fix to this patch after your > > > unused fixup? > > > > Thanks! > > syzbot caught the following: > > WARNING: CPU: 0 PID: 85 at mm/vmscan.c:3140 folio_update_gen+0x23d/0x250 mm/vmscan.c:3140 > ... > > Andrew, can you please fix this in place? OK, but... > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -3138,7 +3138,6 @@ static int folio_update_gen(struct folio *folio, int gen) > unsigned long new_flags, old_flags = READ_ONCE(folio->flags); > > VM_WARN_ON_ONCE(gen >= MAX_NR_GENS); > - VM_WARN_ON_ONCE(!rcu_read_lock_held()); > > do { > /* lru_gen_del_folio() has isolated this page? */ it would be good to know why this assertion is considered incorrect? And a link to the sysbot report? Thanks.