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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: Sun, 25 Jan 2026 23:45:10 +0100 Message-ID: <20260125224541.50226-4-frederic@kernel.org> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20260125224541.50226-1-frederic@kernel.org> References: <20260125224541.50226-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 565A180002 X-Rspamd-Server: rspam07 X-Stat-Signature: 3g5c8x1ex1879t3k77i7y4zh4pj9mdmz X-HE-Tag: 1769381178-881231 X-HE-Meta: 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 gUA== 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