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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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: 77795C0010 X-Stat-Signature: 6wdbxrhjhhktddhj7ua8wcoepf49w1cs X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1769517910-207631 X-HE-Meta: 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 89c7f5ac tVY7xY57oQxZF7Oqtfh5QgG64NxwcHys6YeRBCIMAI/xQ2VbSu40aDdEh5JHEEH84K3cNzJkIIwLk0OEsQSYZV+++Syshy5HxKiQY/TyFTPZPJMgUlDmBpaEGDlDubxHMhiyEXGxBuO4KeVJDg6cVbiWzZ+V9siHgFFPoQG/+C2TtzBlXIlL9hLQl8UG1RiI0r2EmXbEGf01qaw0XFiR9M4fWIlqgw0rfNeEOk+QESIIb7eVYJlyU/CxFecSnXf6Bhf7kpyTcxofjSrz7OM0BT3CjY6IVQk9cN7D3kGfDoitVjHA= 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: Le Mon, Jan 26, 2026 at 05:41:38PM +0100, Michal Hocko a écrit : > 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? This is what guard(rcu)() does, right? Or am I missing something? Thanks. -- Frederic Weisbecker SUSE Labs