From 498f6650aec864e331cae7575fec5f07781d0bf3 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 28 Feb 2018 10:15:32 -0800 Subject: block: Fix a race between the cgroup code and request queue initialization Initialize the request queue lock earlier such that the following race can no longer occur: blk_init_queue_node() blkcg_print_blkgs() blk_alloc_queue_node (1) q->queue_lock = &q->__queue_lock (2) blkcg_init_queue(q) (3) spin_lock_irq(blkg->q->queue_lock) (4) q->queue_lock = lock (5) spin_unlock_irq(blkg->q->queue_lock) (6) (1) allocate an uninitialized queue; (2) initialize queue_lock to its default internal lock; (3) initialize blkcg part of request queue, which will create blkg and then insert it to blkg_list; (4) traverse blkg_list and find the created blkg, and then take its queue lock, here it is the default *internal lock*; (5) *race window*, now queue_lock is overridden with *driver specified lock*; (6) now unlock *driver specified lock*, not the locked *internal lock*, unlock balance breaks. The changes in this patch are as follows: - Move the .queue_lock initialization from blk_init_queue_node() into blk_alloc_queue_node(). - Only override the .queue_lock pointer for legacy queues because it is not useful for blk-mq queues to override this pointer. - For all all block drivers that initialize .queue_lock explicitly, change the blk_alloc_queue() call in the driver into a blk_alloc_queue_node() call and remove the explicit .queue_lock initialization. Additionally, initialize the spin lock that will be used as queue lock earlier if necessary. Reported-by: Joseph Qi Signed-off-by: Bart Van Assche Reviewed-by: Joseph Qi Cc: Christoph Hellwig Cc: Philipp Reisner Cc: Ulf Hansson Cc: Kees Cook Signed-off-by: Jens Axboe --- drivers/block/drbd/drbd_main.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'drivers/block/drbd') diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c index 0a0394aa1b9c..185f1ef00a7c 100644 --- a/drivers/block/drbd/drbd_main.c +++ b/drivers/block/drbd/drbd_main.c @@ -2816,7 +2816,7 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig drbd_init_set_defaults(device); - q = blk_alloc_queue(GFP_KERNEL); + q = blk_alloc_queue_node(GFP_KERNEL, NUMA_NO_NODE, &resource->req_lock); if (!q) goto out_no_q; device->rq_queue = q; @@ -2848,7 +2848,6 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig /* Setting the max_hw_sectors to an odd value of 8kibyte here This triggers a max_bio_size message upon first attach or connect */ blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE_SAFE >> 8); - q->queue_lock = &resource->req_lock; device->md_io.page = alloc_page(GFP_KERNEL); if (!device->md_io.page) -- cgit v1.2.3-55-g7522