On Mon, Apr 29, 2019 at 10:14:59PM +0200, Andrea Parri wrote:

This barrier only applies to the read-modify-write operations; in particular, it does not apply to the atomic_set() primitive.

Replace the barrier with an smp_mb().

Fixes: 6c0ca7ae292ad ("sbitmap: fix wakeup hang after sbq resize") Cc: stable@vger.kernel.org Reported-by: "Paul E. McKenney" paulmck@linux.ibm.com Reported-by: Peter Zijlstra peterz@infradead.org Signed-off-by: Andrea Parri andrea.parri@amarulasolutions.com Cc: Jens Axboe axboe@kernel.dk Cc: Omar Sandoval osandov@fb.com Cc: linux-block@vger.kernel.org

---

lib/sbitmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 155fe38756ecf..4a7fc4915dfc6 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -435,7 +435,7 @@ static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq, * to ensure that the batch size is updated before the wait * counts. */

• smp_mb__before_atomic();
  

• smp_mb();
  

  for (i = 0; i < SBQ_WAIT_QUEUES; i++) atomic_set(&sbq->ws[i].wait_cnt, 1); }

-- 2.7.4

sbitmap_queue_update_wake_batch() won't be called in fast path, and the fix is correct too, so:

Reviewed-by: Ming Lei ming.lei@redhat.com

thanks, Ming