The ->bd_queue member of struct block_device was added in commit 87192a2a49c4 ("vfs: cache request_queue in struct block_device") in v3.3. However, blk_get_backing_dev_info() has been using bdev_get_queue() and grabbing the request_queue through the gendisk since before the git era. At final __blkdev_put() time ->bd_disk is cleared while ->bd_queue is not. The queue remains valid until the final put of the parent disk. The following crash signature results from blk_get_backing_dev_info() trying to lookup the queue through ->bd_disk after the final put of the block device. Simply switch bdev_get_queue() to use ->bd_queue directly which is guaranteed to still be valid at invalidate_partition() time. BUG: unable to handle kernel NULL pointer dereference at 0000000000000568 IP: blk_get_backing_dev_info+0x10/0x20 [..] Call Trace: __inode_attach_wb+0x3a7/0x5d0 __filemap_fdatawrite_range+0xf8/0x100 filemap_write_and_wait+0x40/0x90 fsync_bdev+0x54/0x60 ? bdget_disk+0x30/0x40 invalidate_partition+0x24/0x50 del_gendisk+0xfa/0x230 Cc: <stable@xxxxxxxxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Jens Axboe <axboe@xxxxxx> Cc: Jeff Moyer <jmoyer@xxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Wei Fang <fangwei1@xxxxxxxxxx> Cc: Rabin Vincent <rabinv@xxxxxxxx> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx> Fixes: 87192a2a49c4 ("vfs: cache request_queue in struct block_device") Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> --- block/blk-core.c | 4 ++-- include/linux/blkdev.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 61ba08c58b64..04737548e1e1 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -109,8 +109,8 @@ void blk_queue_congestion_threshold(struct request_queue *q) * @bdev: device * * Locates the passed device's request queue and returns the address of its - * backing_dev_info. This function can only be called if @bdev is opened - * and the return value is never NULL. + * backing_dev_info. This function can only be called while there is an + * active reference against the parent gendisk. */ struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) { diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 83695641bd5e..27779709f821 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -962,7 +962,7 @@ bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie); static inline struct request_queue *bdev_get_queue(struct block_device *bdev) { - return bdev->bd_disk->queue; /* this is never NULL */ + return bdev->bd_queue; /* this is never NULL */ } /* -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html