======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
kworker/0:3/5816 is trying to acquire lock:
ffff88802463e358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: mddev_lock_nointr drivers/md/md.h:734 [inline]
ffff88802463e358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: md_start_sync+0xc4/0xea0 drivers/md/md.c:10275

but task is already holding lock:
ffffc90004e7fd08 ((work_completion)(&mddev->sync_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:

-> #3 ((work_completion)(&mddev->sync_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

-> #2 ((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:665
       do_dentry_open+0x6ab/0x14d0 fs/open.c:996
       vfs_open+0x82/0x3f0 fs/open.c:1101
       do_open fs/namei.c:4837 [inline]
       path_openat+0x19fa/0x2440 fs/namei.c:5000
       do_file_open+0x20e/0x430 fs/namei.c:5029
       do_sys_openat2+0x10f/0x1e0 fs/open.c:1417
       do_sys_open fs/open.c:1423 [inline]
       __do_compat_sys_openat fs/open.c:1485 [inline]
       __se_compat_sys_openat fs/open.c:1483 [inline]
       __ia32_compat_sys_openat+0x12d/0x210 fs/open.c:1483
       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 (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+0x1a4/0x1bd0 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
       md_add_new_disk+0x4b6/0x1820 drivers/md/md.c:7507
       md_ioctl+0x2bec/0x36d0 drivers/md/md.c:8499
       compat_blkdev_ioctl+0x682/0x7b0 block/ioctl.c:854
       __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
       __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
       __ia32_compat_sys_ioctl+0x2cf/0x360 fs/ioctl.c:638
       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 (&mddev->reconfig_mutex){+.+.}-{4:4}:
       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
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
       mddev_lock_nointr drivers/md/md.h:734 [inline]
       md_start_sync+0xc4/0xea0 drivers/md/md.c:10275
       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: