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Commit 22540ca3 authored by Hillf Danton's avatar Hillf Danton Committed by Greg Kroah-Hartman
Browse files

workqueue: don't use wq_select_unbound_cpu() for bound works 



commit aa202f1f56960c60e7befaa0f49c72b8fa11b0a8 upstream.

wq_select_unbound_cpu() is designed for unbound workqueues only, but
it's wrongly called when using a bound workqueue too.

Fixing this ensures work queued to a bound workqueue with
cpu=WORK_CPU_UNBOUND always runs on the local CPU.

Before, that would happen only if wq_unbound_cpumask happened to include
it (likely almost always the case), or was empty, or we got lucky with
forced round-robin placement.  So restricting
/sys/devices/virtual/workqueue/cpumask to a small subset of a machine's
CPUs would cause some bound work items to run unexpectedly there.

Fixes: ef557180 ("workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs")
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: default avatarHillf Danton <hdanton@sina.com>
[dj: massage changelog]
Signed-off-by: default avatarDaniel Jordan <daniel.m.jordan@oracle.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 70612567

kernel/workqueue.c

+8 −6
Original line number Diff line number Diff line
@@ -1417,14 +1417,16 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, 
		return;

	rcu_read_lock();

retry:

	/* pwq which will be used unless @work is executing elsewhere */

	if (wq->flags & WQ_UNBOUND) {

		if (req_cpu == WORK_CPU_UNBOUND)

			cpu = wq_select_unbound_cpu(raw_smp_processor_id());



	/* pwq which will be used unless @work is executing elsewhere */

	if (!(wq->flags & WQ_UNBOUND))

		pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);

	else

		pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));

	} else {

		if (req_cpu == WORK_CPU_UNBOUND)

			cpu = raw_smp_processor_id();

		pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);

	}



	/*

	 * If @work was previously on a different pool, it might still be