linux-kernel - [PATCH -tip V2 04/10] workqueue: don't set the worker's cpumask when kthread_bind

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Date:   Sat, 19 Dec 2020 01:09:13 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Valentin Schneider <valentin.schneider@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Qian Cai <cai@...hat.com>,
        Vincent Donnefort <vincent.donnefort@....com>,
        Lai Jiangshan <laijs@...ux.alibaba.com>,
        Tejun Heo <tj@...nel.org>,
        Lai Jiangshan <jiangshanlai@...il.com>
Subject: [PATCH -tip V2 04/10] workqueue: don't set the worker's cpumask when kthread_bind_mask()

From: Lai Jiangshan <laijs@...ux.alibaba.com>

There might be no online cpu in the pool->attrs->cpumask.
We will set the worker's cpumask later in worker_attach_to_pool().

Cc: Peter Zijlstra <peterz@...radead.org>
Acked-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 kernel/workqueue.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 4d7575311198..5f3c86eaed7a 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1948,7 +1948,15 @@ static struct worker *create_worker(struct worker_pool *pool)
 		goto fail;
 
 	set_user_nice(worker->task, pool->attrs->nice);
-	kthread_bind_mask(worker->task, pool->attrs->cpumask);
+
+	/*
+	 * Set PF_NO_SETAFFINITY via kthread_bind_mask().  We use
+	 * cpu_possible_mask instead of pool->attrs->cpumask, because
+	 * there might not be any online cpu in the pool->attrs->cpumask.
+	 * The cpumask of the worker will be set properly later in
+	 * worker_attach_to_pool().
+	 */
+	kthread_bind_mask(worker->task, cpu_possible_mask);
 
 	/* successful, attach the worker to the pool */
 	worker_attach_to_pool(worker, pool);
-- 
2.19.1.6.gb485710b