block: Free queue resources at blk_release_queue()

A kernel crash is observed when a mounted ext3/ext4 filesystem is
physically removed. The problem is that blk_cleanup_queue() frees up
some resources eg by calling elevator_exit(), which are not checked for
in normal operation. So we should rather move these calls to the
destructor function blk_release_queue() as at that point all remaining
references are gone. However, in doing so we have to ensure that any
externally supplied queue_lock is disconnected as the driver might free
up the lock after the call of blk_cleanup_queue(),

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 5 insertions, 0 deletions

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index e681805cdb47..60fda88c57f0 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -479,6 +479,11 @@ static void blk_release_queue(struct kobject *kobj)
 
         blk_sync_queue(q);
 
+        if (q->elevator)
+                elevator_exit(q->elevator);
+
+        blk_throtl_exit(q);
+
         if (rl->rq_pool)
                 mempool_destroy(rl->rq_pool);