From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Lai Jiangshan <jiangshan.ljs@antgroup.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Tejun Heo <tj@kernel.org>, Petr Mladek <pmladek@suse.com>,
Michal Hocko <mhocko@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Wedson Almeida Filho <wedsonaf@google.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Valentin Schneider <vschneid@redhat.com>
Subject: [RFC PATCH 1/8] workqueue: Unconditionally set cpumask in worker_attach_to_pool()
Date: Thu, 4 Aug 2022 16:41:28 +0800 [thread overview]
Message-ID: <20220804084135.92425-2-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20220804084135.92425-1-jiangshanlai@gmail.com>
From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
If a worker is spuriously woken up after kthread_bind_mask() but before
worker_attach_to_pool(), and there are some cpu-hot-[un]plug happening
during the same interval, the worker task might be pushed away from its
bound CPU with its affinity changed by the scheduler and worker_attach_to_pool()
doesn't rebind it properly.
Do unconditionally affinity binding in worker_attach_to_pool() to fix
the problem.
Prepare for moving worker_attach_to_pool() from create_worker() to the
starting of worker_thread() which will really cause the said interval
even without spurious wakeup.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>,
Cc: Petr Mladek <pmladek@suse.com>
Cc: Michal Hocko <mhocko@suse.com>,
Cc: Peter Zijlstra <peterz@infradead.org>,
Cc: Wedson Almeida Filho <wedsonaf@google.com>
Fixes: 640f17c82460 ("workqueue: Restrict affinity change to rescuer")
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
kernel/workqueue.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 1ea50f6be843..928aad7d6123 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1872,8 +1872,11 @@ static void worker_attach_to_pool(struct worker *worker,
else
kthread_set_per_cpu(worker->task, pool->cpu);
- if (worker->rescue_wq)
- set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
+ /*
+ * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
+ * online CPUs. It'll be re-applied when any of the CPUs come up.
+ */
+ set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
list_add_tail(&worker->node, &pool->workers);
worker->pool = pool;
--
2.19.1.6.gb485710b
next prev parent reply other threads:[~2022-08-04 8:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-04 8:41 [RFC PATCH 0/8] workqueue: Fix for prematurely wakeups and cleanups Lai Jiangshan
2022-08-04 8:41 ` Lai Jiangshan [this message]
2022-08-16 21:18 ` [RFC PATCH 1/8] workqueue: Unconditionally set cpumask in worker_attach_to_pool() Tejun Heo
2022-08-18 14:39 ` Lai Jiangshan
2022-09-12 7:54 ` Peter Zijlstra
2022-08-04 8:41 ` [RFC PATCH 2/8] workqueue: Make create_worker() safe against prematurely wakeups Lai Jiangshan
[not found] ` <20220804123520.1660-1-hdanton@sina.com>
2022-08-05 2:30 ` Lai Jiangshan
2022-08-16 21:46 ` Tejun Heo
2022-08-04 8:41 ` [RFC PATCH 3/8] workqueue: Set PF_NO_SETAFFINITY instead of kthread_bind_mask() Lai Jiangshan
2022-08-04 8:41 ` [RFC PATCH 4/8] workqueue: Set/Clear PF_WQ_WORKER while attaching/detaching Lai Jiangshan
2022-08-04 8:41 ` [RFC PATCH 5/8] workqueue: Use worker_set_flags() in worker_enter_idle() Lai Jiangshan
2022-08-04 8:41 ` [RFC PATCH 6/8] workqueue: Simplify the starting of the newly created worker Lai Jiangshan
2022-08-04 8:41 ` [RFC PATCH 7/8] workqueue: Remove the outer loop in maybe_create_worker() Lai Jiangshan
2022-08-16 22:08 ` Tejun Heo
2022-08-18 14:44 ` Lai Jiangshan
2022-08-19 17:29 ` Tejun Heo
2022-08-04 8:41 ` [RFC PATCH 8/8] workqueue: Move the locking out of maybe_create_worker() Lai Jiangshan
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