workqueue: use system_highpri_wq for highpri workers in rebind_workers()

In rebind_workers(), we do inserting a work to rebind to cpu for busy workers.
Currently, in this case, we use only system_wq. This makes a possible
error situation as there is mismatch between cwq->pool and worker->pool.

To prevent this, we should use system_highpri_wq for highpri worker
to match theses. This implements it.

tj: Rephrased comment a bit.

Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 14 insertions, 4 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 329c404b68c2..8936761b814a 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1741,6 +1741,7 @@ retry:
         /* rebind busy workers */
         for_each_busy_worker(worker, i, pos, gcwq) {
                 struct work_struct *rebind_work = &worker->rebind_work;
+                struct workqueue_struct *wq;
 
                 /* morph UNBOUND to REBIND */
                 worker->flags &= ~WORKER_UNBOUND;
@@ -1750,11 +1751,20 @@ retry:
                                      work_data_bits(rebind_work)))
                         continue;
 
-                /* wq doesn't matter, use the default one */
                 debug_work_activate(rebind_work);
-                insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
-                            worker->scheduled.next,
-                            work_color_to_flags(WORK_NO_COLOR));
+
+                /*
+                 * wq doesn't really matter but let's keep @worker->pool
+                 * and @cwq->pool consistent for sanity.
+                 */
+                if (worker_pool_pri(worker->pool))
+                        wq = system_highpri_wq;
+                else
+                        wq = system_wq;
+
+                insert_work(get_cwq(gcwq->cpu, wq), rebind_work,
+                        worker->scheduled.next,
+                        work_color_to_flags(WORK_NO_COLOR));
         }
 }