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: dac56212e8127 ("bio: skip atomic inc/dec of ->bi_cnt for most use cases") 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 Reviewed-by: Ming Lei ming.lei@redhat.com Cc: Jens Axboe axboe@kernel.dk Cc: Ming Lei ming.lei@redhat.com Cc: linux-block@vger.kernel.org Cc: "Paul E. McKenney" paulmck@linux.ibm.com Cc: Peter Zijlstra peterz@infradead.org --- include/linux/bio.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/bio.h b/include/linux/bio.h index ea73df36529ad..0f23b56826403 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -210,7 +210,7 @@ static inline void bio_cnt_set(struct bio *bio, unsigned int count) { if (count != 1) { bio->bi_flags |= (1 << BIO_REFFED); - smp_mb__before_atomic(); + smp_mb(); } atomic_set(&bio->__bi_cnt, count); }