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Miller" , Eric Dumazet , Gabriele Monaco , Greg Kroah-Hartman , Ingo Molnar , Jakub Kicinski , Jens Axboe , Johannes Weiner , Lai Jiangshan , Marco Crivellari , Michal Hocko , 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: [PATCH 03/33] memcg: Prepare to protect against concurrent isolated cpuset change Date: Thu, 1 Jan 2026 23:13:28 +0100 Message-ID: <20260101221359.22298-4-frederic@kernel.org> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20260101221359.22298-1-frederic@kernel.org> References: <20260101221359.22298-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 5788D100006 X-Stat-Signature: fjesissud9mqajpbg3chakjygfu1mghs X-HE-Tag: 1767305678-671063 X-HE-Meta: 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 ho9pYD9R CAuftUxu+2TVh+u8Y/q3i+IkYtQ83Eqbf3usxVaxOCmfNiMIrNB5GpPj3o+mdT9unuqGzI+OzMNAtT/mKdhyUsCMVW1MWuemeh/rZ5poJb/UH1QEBNOaqh+xxQWyDIB7lHBDsvUoVPXnt+xvWgCcSfRO8r17l4kDkvVDSXiEjsVsfpMOVPZZhIyC+lsguWyyi717Ug3bBwB9i2a3Z01Hlfvcwq+86ftOdkOKpanZnLNOkMJhqJL767AdNGHVCbq04Ml5ExLjf9X4XnXA= 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: 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); +} + /* * Drains all per-CPU charge caches for given root_memcg resp. subtree * of the hierarchy under it. @@ -2032,8 +2045,8 @@ void drain_all_stock(struct mem_cgroup *root_memcg) &memcg_st->flags)) { if (cpu == curcpu) drain_local_memcg_stock(&memcg_st->work); - else if (!cpu_is_isolated(cpu)) - schedule_work_on(cpu, &memcg_st->work); + else + schedule_drain_work(cpu, &memcg_st->work); } if (!test_bit(FLUSHING_CACHED_CHARGE, &obj_st->flags) && @@ -2042,8 +2055,8 @@ void drain_all_stock(struct mem_cgroup *root_memcg) &obj_st->flags)) { if (cpu == curcpu) drain_local_obj_stock(&obj_st->work); - else if (!cpu_is_isolated(cpu)) - schedule_work_on(cpu, &obj_st->work); + else + schedule_drain_work(cpu, &obj_st->work); } } migrate_enable(); -- 2.51.1