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[109.81.26.156]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-435b1f74b15sm31194587f8f.35.2026.01.26.08.41.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Jan 2026 08:41:39 -0800 (PST) Date: Mon, 26 Jan 2026 17:41:38 +0100 From: Michal Hocko To: Frederic Weisbecker Cc: LKML , Michal =?iso-8859-1?Q?Koutn=FD?= , Andrew Morton , Bjorn Helgaas , Catalin Marinas , Chen Ridong , Danilo Krummrich , "David S . Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Muchun Song , Paolo Abeni , Peter Zijlstra , Phil Auld , "Rafael J . Wysocki" , Roman Gushchin , Shakeel Butt , Simon Horman , Tejun Heo , Thomas Gleixner , Vlastimil Babka , Waiman Long , Will Deacon , cgroups@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH 03/33] memcg: Prepare to protect against concurrent isolated cpuset change Message-ID: References: <20260125224541.50226-1-frederic@kernel.org> <20260125224541.50226-4-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260125224541.50226-4-frederic@kernel.org> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 758FC20002 X-Stat-Signature: d4i6sg5ya4etj97aphh9dxkt8b8e385z X-Rspam-User: X-HE-Tag: 1769445701-120398 X-HE-Meta: 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 MaHCR/BH SgXGMoZdguyiq8yMZcvs3CZeanKJU/0K0wnaAF4k7MlrLKa+92uUVHJ/sThxIdeOEMeVt5nJyJcXBRszGm1P48nce5u6upJvOlsGklcc1HRndwOoQPesU9ckHlQOmnHORJgu0RD/fI+voq0GWxWmAEG2u/EcQuaxx3fLjebqsVDLT+pL7oDWCzlHdGVOa6x/Sy1Mel3snSFJa5pLRTdqn6fLgIhQUbQX6+QuRRn4UhVLe8QZY4eXYFFq/RMQteZ2h50Gq3qED3UhYDC0ud5gN0UGcEHfZnqMGSxuVpvu4soXa/PFqieGawvGO87EzR6dYfeIKdGZ6UnYuUibYmVY1bMlPDQ== 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 Sun 25-01-26 23:45:10, Frederic Weisbecker wrote: > The HK_TYPE_DOMAIN housekeeping cpumask will soon be made modifiable at > runtime. In order to synchronize against memcg workqueue to make sure > that no asynchronous draining is pending or executing on a newly made > isolated CPU, target and queue a drain work under the same RCU critical > section. > > Whenever housekeeping will update the HK_TYPE_DOMAIN cpumask, a memcg > workqueue flush will also be issued in a further change to make sure > that no work remains pending after a CPU has been made isolated. > > Signed-off-by: Frederic Weisbecker > --- > mm/memcontrol.c | 21 +++++++++++++++++---- > 1 file changed, 17 insertions(+), 4 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index be810c1fbfc3..2289a0299331 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2003,6 +2003,19 @@ static bool is_memcg_drain_needed(struct memcg_stock_pcp *stock, > return flush; > } > > +static void schedule_drain_work(int cpu, struct work_struct *work) > +{ > + /* > + * Protect housekeeping cpumask read and work enqueue together > + * in the same RCU critical section so that later cpuset isolated > + * partition update only need to wait for an RCU GP and flush the > + * pending work on newly isolated CPUs. > + */ > + guard(rcu)(); > + if (!cpu_is_isolated(cpu)) > + schedule_work_on(cpu, work); Shouldn't this in the guarded rcu section? -- Michal Hocko SUSE Labs