Patch "dm: free io_barrier after blk_cleanup_queue call" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

dm: free io_barrier after blk_cleanup_queue call

to the 4.8-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:
dm-free-io_barrier-after-blk_cleanup_queue-call.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Tahsin Erdogan <[email protected]>
Date: Mon, 10 Oct 2016 05:35:19 -0700
Subject: dm: free io_barrier after blk_cleanup_queue call

From: Tahsin Erdogan <[email protected]>

commit d09960b0032174eb493c4c13be5b9c9ef36dc9a7 upstream.

dm_old_request_fn() has paths that access md->io_barrier. The party destroying io_barrier should ensure that no future execution of dm_old_request_fn() is possible. Move io_barrier destruction to below blk_cleanup_queue() to ensure this and avoid a NULL pointer crash during request-based DM device shutdown.

---
 drivers/md/dm.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -1423,8 +1423,6 @@ static void cleanup_mapped_device(struct
 	if (md->bs)
 		bioset_free(md->bs);
 
-	cleanup_srcu_struct(&md->io_barrier);
-
 	if (md->disk) {
 		spin_lock(&_minor_lock);
 		md->disk->private_data = NULL;

@@ -1436,6 +1434,8 @@ static void cleanup_mapped_device(struct
 	if (md->queue)
 		blk_cleanup_queue(md->queue);
 
+	cleanup_srcu_struct(&md->io_barrier);
+
 	if (md->bdev) {
 		bdput(md->bdev);
 		md->bdev = NULL;

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/dm-free-io_barrier-after-blk_cleanup_queue-call.patch