====================================================== WARNING: possible circular locking dependency detected 5.13.0-rc2-next-20210518-syzkaller #0 Not tainted ------------------------------------------------------ kworker/0:0/5 is trying to acquire lock: ffff88814608aea0 (&bdev->bd_mutex){+.+.}-{3:3}, at: del_gendisk+0x250/0x9e0 block/genhd.c:618 but task is already holding lock: ffffffff8c9e4c70 (bdev_lookup_sem){++++}-{3:3}, at: del_gendisk+0x222/0x9e0 block/genhd.c:616 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (bdev_lookup_sem){++++}-{3:3}: down_write+0x92/0x150 kernel/locking/rwsem.c:1406 del_gendisk+0x222/0x9e0 block/genhd.c:616 md_free+0xcb/0x200 drivers/md/md.c:5602 kobject_cleanup lib/kobject.c:705 [inline] kobject_release lib/kobject.c:736 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1c8/0x540 lib/kobject.c:753 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 -> #4 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}: process_one_work+0x8fc/0x1600 kernel/workqueue.c:2251 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 -> #3 ((wq_completion)md_misc){+.+.}-{0:0}: flush_workqueue+0x110/0x13e0 kernel/workqueue.c:2786 md_alloc+0x29/0x1170 drivers/md/md.c:5674 md_probe+0x69/0x70 drivers/md/md.c:5780 blk_request_module+0x111/0x1d0 block/genhd.c:692 blkdev_get_no_open+0x225/0x2b0 fs/block_dev.c:1371 blkdev_get_by_dev fs/block_dev.c:1439 [inline] blkdev_get_by_dev+0x76/0x660 fs/block_dev.c:1425 blkdev_open+0x154/0x2b0 fs/block_dev.c:1548 do_dentry_open+0x4b9/0x11c0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c09/0x27d0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 do_sys_openat2+0x16d/0x420 fs/open.c:1196 do_sys_open fs/open.c:1212 [inline] __do_sys_openat fs/open.c:1228 [inline] __se_sys_openat fs/open.c:1223 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1223 do_syscall_64+0x31/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #2 (major_names_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 __register_blkdev+0x2b/0x3e0 block/genhd.c:225 register_mtd_blktrans+0x85/0x3c0 drivers/mtd/mtd_blkdevs.c:534 do_one_initcall+0x103/0x650 init/main.c:1290 do_initcall_level init/main.c:1363 [inline] do_initcalls init/main.c:1379 [inline] do_basic_setup init/main.c:1399 [inline] kernel_init_freeable+0x643/0x6cc init/main.c:1601 kernel_init+0xd/0x1c0 init/main.c:1488 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 -> #1 (mtd_table_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 blktrans_open+0x69/0x600 drivers/mtd/mtd_blkdevs.c:212 __blkdev_get+0x135/0xa30 fs/block_dev.c:1305 blkdev_get_by_dev fs/block_dev.c:1453 [inline] blkdev_get_by_dev+0x200/0x660 fs/block_dev.c:1425 blkdev_open+0x154/0x2b0 fs/block_dev.c:1548 do_dentry_open+0x4b9/0x11c0 fs/open.c:826 do_open fs/namei.c:3361 [inline] path_openat+0x1c09/0x27d0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 do_sys_openat2+0x16d/0x420 fs/open.c:1196 do_sys_open fs/open.c:1212 [inline] __do_sys_open fs/open.c:1220 [inline] __se_sys_open fs/open.c:1216 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1216 do_syscall_64+0x31/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (&bdev->bd_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:2938 [inline] check_prevs_add kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x2a17/0x5230 kernel/locking/lockdep.c:4902 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477 __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 del_gendisk+0x250/0x9e0 block/genhd.c:618 md_free+0xcb/0x200 drivers/md/md.c:5602 kobject_cleanup lib/kobject.c:705 [inline] kobject_release lib/kobject.c:736 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1c8/0x540 lib/kobject.c:753 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 other info that might help us debug this: Chain exists of: &bdev->bd_mutex --> (work_completion)(&mddev->del_work) --> bdev_lookup_sem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(bdev_lookup_sem); lock((work_completion)(&mddev->del_work)); lock(bdev_lookup_sem); lock(&bdev->bd_mutex); *** DEADLOCK *** 3 locks held by kworker/0:0/5: #0: ffff888141988538 ((wq_completion)md_misc){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff888141988538 ((wq_completion)md_misc){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff888141988538 ((wq_completion)md_misc){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff888141988538 ((wq_completion)md_misc){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff888141988538 ((wq_completion)md_misc){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888141988538 ((wq_completion)md_misc){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246 #1: ffffc90000ca7da8 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250 #2: ffffffff8c9e4c70 (bdev_lookup_sem){++++}-{3:3}, at: del_gendisk+0x222/0x9e0 block/genhd.c:616 stack backtrace: CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.13.0-rc2-next-20210518-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: md_misc mddev_delayed_delete Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x13e/0x1d6 lib/dump_stack.c:129 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2129 check_prev_add kernel/locking/lockdep.c:2938 [inline] check_prevs_add kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x2a17/0x5230 kernel/locking/lockdep.c:4902 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477 __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 del_gendisk+0x250/0x9e0 block/genhd.c:618 md_free+0xcb/0x200 drivers/md/md.c:5602 kobject_cleanup lib/kobject.c:705 [inline] kobject_release lib/kobject.c:736 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1c8/0x540 lib/kobject.c:753 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:313