====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ kworker/0:0/9 is trying to acquire lock: ffff88806d5780f8 (kn->active#97){++++}-{0:0}, at: __kernfs_remove+0x34c/0xbc0 fs/kernfs/dir.c:1578 but task is already holding lock: ffffc900001b7d08 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 process_one_work+0xa32/0x1b10 kernel/workqueue.c:3372 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #3 ((wq_completion)md_misc){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 touch_wq_lockdep_map+0xad/0x1c0 kernel/workqueue.c:4111 __flush_workqueue+0x131/0x1200 kernel/workqueue.c:4153 md_alloc+0x30/0x10a0 drivers/md/md.c:6334 md_alloc_and_put drivers/md/md.c:6423 [inline] md_probe drivers/md/md.c:6439 [inline] md_probe+0x73/0xf0 drivers/md/md.c:6434 blk_probe_dev+0x149/0x1e0 block/genhd.c:888 blk_request_module+0x16/0xc0 block/genhd.c:901 blkdev_get_no_open+0x9b/0xf0 block/bdev.c:870 blkdev_open+0x141/0x4f0 block/fops.c:671 do_dentry_open+0x674/0x1470 fs/open.c:1000 vfs_open_consume+0xcc/0x460 fs/open.c:1131 do_open fs/namei.c:4845 [inline] path_openat+0x1551/0x2430 fs/namei.c:5010 do_file_open+0x20e/0x430 fs/namei.c:5039 do_sys_openat2+0x163/0x1d0 fs/open.c:1442 do_sys_open fs/open.c:1448 [inline] __do_compat_sys_openat fs/open.c:1510 [inline] __se_compat_sys_openat fs/open.c:1508 [inline] __ia32_compat_sys_openat+0x12d/0x210 fs/open.c:1508 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline] __do_fast_syscall_32+0x13a/0x8b0 arch/x86/entry/syscall_32.c:291 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #2 (major_names_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1c20 kernel/locking/mutex.c:821 blk_probe_dev+0x28/0x1e0 block/genhd.c:885 blk_request_module+0x16/0xc0 block/genhd.c:901 blkdev_get_no_open+0x9b/0xf0 block/bdev.c:870 bdev_file_open_by_dev block/bdev.c:1091 [inline] bdev_file_open_by_dev+0x70/0x210 block/bdev.c:1079 md_import_device+0x120/0x360 drivers/md/md.c:3847 new_dev_store+0x423/0x8d0 drivers/md/md.c:4867 md_attr_store+0x1c5/0x330 drivers/md/md.c:6158 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6af/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline] __do_fast_syscall_32+0x13a/0x8b0 arch/x86/entry/syscall_32.c:291 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #1 (&mddev->reconfig_mutex){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1c20 kernel/locking/mutex.c:821 mddev_lock drivers/md/md.h:713 [inline] array_state_store+0x174/0xcf0 drivers/md/md.c:4705 md_attr_store+0x1c5/0x330 drivers/md/md.c:6158 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6af/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline] __do_fast_syscall_32+0x13a/0x8b0 arch/x86/entry/syscall_32.c:291 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (kn->active#97){++++}-{0:0}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 kernfs_drain+0x4f0/0x600 fs/kernfs/dir.c:534 __kernfs_remove+0x34c/0xbc0 fs/kernfs/dir.c:1578 kernfs_remove_by_name_ns+0x7c/0x120 fs/kernfs/dir.c:1796 kernfs_remove_by_name include/linux/kernfs.h:644 [inline] remove_files+0x96/0x1c0 fs/sysfs/group.c:28 sysfs_remove_group+0x8b/0x1b0 fs/sysfs/group.c:328 sysfs_remove_groups fs/sysfs/group.c:352 [inline] sysfs_remove_groups+0x60/0xb0 fs/sysfs/group.c:344 __kobject_del+0x89/0x220 lib/kobject.c:595 kobject_cleanup lib/kobject.c:680 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x348/0x640 lib/kobject.c:737 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Chain exists of: kn->active#97 --> (wq_completion)md_misc --> (work_completion)(&mddev->del_work) Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((work_completion)(&mddev->del_work)); lock((wq_completion)md_misc); lock((work_completion)(&mddev->del_work)); lock(kn->active#97); *** DEADLOCK *** locks held by kworker/0:0/9: 2, last CPU#0: #0: ffff888022dee540 ((wq_completion)md_misc){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371 #1: ffffc900001b7d08 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372 stack backtrace: CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: md_misc mddev_delayed_delete Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2087 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 kernfs_drain+0x4f0/0x600 fs/kernfs/dir.c:534 __kernfs_remove+0x34c/0xbc0 fs/kernfs/dir.c:1578 kernfs_remove_by_name_ns+0x7c/0x120 fs/kernfs/dir.c:1796 kernfs_remove_by_name include/linux/kernfs.h:644 [inline] remove_files+0x96/0x1c0 fs/sysfs/group.c:28 sysfs_remove_group+0x8b/0x1b0 fs/sysfs/group.c:328 sysfs_remove_groups fs/sysfs/group.c:352 [inline] sysfs_remove_groups+0x60/0xb0 fs/sysfs/group.c:344 __kobject_del+0x89/0x220 lib/kobject.c:595 kobject_cleanup lib/kobject.c:680 [inline] kobject_release lib/kobject.c:720 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x348/0x640 lib/kobject.c:737 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245