From: Peter Zijlstra peterz@infradead.org
stable inclusion from linux-4.19.174 commit 1746d1dcae9a960052b7a956523cc1719f71513c
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[ Upstream commit 640f17c82460e9724fd256f0a1f5d99e7ff0bda4 ]
create_worker() will already set the right affinity using kthread_bind_mask(), this means only the rescuer will need to change it's affinity.
Howveer, while in cpu-hot-unplug a regular task is not allowed to run on online&&!active as it would be pushed away quite agressively. We need KTHREAD_IS_PER_CPU to survive in that environment.
Therefore set the affinity after getting that magic flag.
Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Valentin Schneider valentin.schneider@arm.com Tested-by: Valentin Schneider valentin.schneider@arm.com Link: https://lkml.kernel.org/r/20210121103506.826629830@infradead.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- kernel/workqueue.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 4f05c714f99c..1ffc523edb65 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1729,12 +1729,6 @@ static void worker_attach_to_pool(struct worker *worker, { mutex_lock(&wq_pool_attach_mutex);
- /* - * 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); - /* * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains * stable across this function. See the comments above the flag @@ -1743,6 +1737,9 @@ static void worker_attach_to_pool(struct worker *worker, if (pool->flags & POOL_DISASSOCIATED) worker->flags |= WORKER_UNBOUND;
+ if (worker->rescue_wq) + set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); + list_add_tail(&worker->node, &pool->workers); worker->pool = pool;