workqueue: swap set_cpus_allowed_ptr() and PF_NO_SETAFFINITY

Move the setting of PF_NO_SETAFFINITY up before set_cpus_allowed()
in create_worker(). Otherwise userland can change ->cpus_allowed
in between.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 5 insertions, 4 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 987293d03ebc..f8942429268b 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1736,16 +1736,17 @@ static struct worker *create_worker(struct worker_pool *pool)
         if (IS_ERR(worker->task))
                 goto fail;
 
+        set_user_nice(worker->task, pool->attrs->nice);
+
+        /* prevent userland from meddling with cpumask of workqueue workers */
+        worker->task->flags |= PF_NO_SETAFFINITY;
+
         /*
          * 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_user_nice(worker->task, pool->attrs->nice);
         set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
 
-        /* prevent userland from meddling with cpumask of workqueue workers */
-        worker->task->flags |= PF_NO_SETAFFINITY;
-
         /*
          * The caller is responsible for ensuring %POOL_DISASSOCIATED
          * remains stable across this function.  See the comments above the