This is a note to let you know that I've just added the patch titled rds: add missing barrier to release_refill to the 5.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: rds-add-missing-barrier-to-release_refill.patch and it can be found in the queue-5.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 9f414eb409daf4f778f011cf8266d36896bb930b Mon Sep 17 00:00:00 2001 From: Mikulas Patocka <mpatocka@xxxxxxxxxx> Date: Wed, 10 Aug 2022 09:00:42 -0400 Subject: rds: add missing barrier to release_refill From: Mikulas Patocka <mpatocka@xxxxxxxxxx> commit 9f414eb409daf4f778f011cf8266d36896bb930b upstream. The functions clear_bit and set_bit do not imply a memory barrier, thus it may be possible that the waitqueue_active function (which does not take any locks) is moved before clear_bit and it could miss a wakeup event. Fix this bug by adding a memory barrier after clear_bit. Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/rds/ib_recv.c | 1 + 1 file changed, 1 insertion(+) --- a/net/rds/ib_recv.c +++ b/net/rds/ib_recv.c @@ -363,6 +363,7 @@ static int acquire_refill(struct rds_con static void release_refill(struct rds_connection *conn) { clear_bit(RDS_RECV_REFILL, &conn->c_flags); + smp_mb__after_atomic(); /* We don't use wait_on_bit()/wake_up_bit() because our waking is in a * hot path and finding waiters is very rare. We don't want to walk Patches currently in stable-queue which might be from mpatocka@xxxxxxxxxx are queue-5.19/rds-add-missing-barrier-to-release_refill.patch