From: Peter Zijlstra On Wed, 2006-08-09 at 07:57 +0200, Rolf Eike Beer wrote: > ============================================= > [ INFO: possible recursive locking detected ] > --------------------------------------------- > parted/7929 is trying to acquire lock: > (&bdev->bd_mutex){--..}, at: [] __blkdev_put+0x1e/0x13c > > but task is already holding lock: > (&bdev->bd_mutex){--..}, at: [] do_open+0x72/0x3a8 > > other info that might help us debug this: > 1 lock held by parted/7929: > #0: (&bdev->bd_mutex){--..}, at: [] do_open+0x72/0x3a8 > stack backtrace: > [] show_trace_log_lvl+0x58/0x15b > [] show_trace+0xd/0x10 > [] dump_stack+0x17/0x1a > [] __lock_acquire+0x753/0x99c > [] lock_acquire+0x4a/0x6a > [] mutex_lock_nested+0xc8/0x20c > [] __blkdev_put+0x1e/0x13c > [] blkdev_put+0xa/0xc > [] do_open+0x336/0x3a8 > [] blkdev_open+0x1f/0x4c > [] __dentry_open+0xc7/0x1aa > [] nameidata_to_filp+0x1c/0x2e > [] do_filp_open+0x2e/0x35 > [] do_sys_open+0x38/0x68 > [] sys_open+0x16/0x18 > [] sysenter_past_esp+0x56/0x8d OK, I'm having a look here; its all new to me so bear with me. blkdev_open() calls do_open(bdev, ...,BD_MUTEX_NORMAL) and takes mutex_lock_nested(&bdev->bd_mutex, BD_MUTEX_NORMAL) then something fails, and we're thrown to: out_first: where if (bdev != bdev->bd_contains) blkdev_put(bdev->bd_contains) which is __blkdev_put(bdev->bd_contains, BD_MUTEX_NORMAL) which does mutex_lock_nested(&bdev->bd_contains->bd_mutex, BD_MUTEX_NORMAL) <--- lockdep trigger When going to out_first, dbev->bd_contains is either bdev or whole, and since we take the branch it must be whole. So it seems to me the following patch would be the right one: Signed-off-by: Peter Zijlstra Cc: Arjan van de Ven Signed-off-by: Andrew Morton --- fs/block_dev.c | 2 +- 1 files changed, 1 insertion(+), 1 deletion(-) diff -puN fs/block_dev.c~lockdep-fix-blkdev_open-warning fs/block_dev.c --- a/fs/block_dev.c~lockdep-fix-blkdev_open-warning +++ a/fs/block_dev.c @@ -980,7 +980,7 @@ out_first: bdev->bd_disk = NULL; bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info; if (bdev != bdev->bd_contains) - blkdev_put(bdev->bd_contains); + __blkdev_put(bdev->bd_contains, BD_MUTEX_WHOLE); bdev->bd_contains = NULL; put_disk(disk); module_put(owner); _