======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.1383/9987 is trying to acquire lock:
ffff88807dbe82c0 (&mddev->reconfig_mutex){+.+.}-{3:3}, at: mddev_lock drivers/md/md.h:543 [inline]
ffff88807dbe82c0 (&mddev->reconfig_mutex){+.+.}-{3:3}, at: raid_disks_store+0xb6/0x4f0 drivers/md/md.c:4251

but task is already holding lock:
ffff8881445f43a8 (kn->active#743){++++}-{0:0}, at: kernfs_fop_write_iter+0x1fd/0x500 fs/kernfs/file.c:288

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (kn->active#743){++++}-{0:0}:
       kernfs_drain fs/kernfs/dir.c:478 [inline]
       __kernfs_remove+0x5da/0xcb0 fs/kernfs/dir.c:1372
       kernfs_remove+0x1d/0x30 fs/kernfs/dir.c:1406
       __kobject_del+0xe0/0x2e0 lib/kobject.c:628
       kobject_del+0x41/0x60 lib/kobject.c:651
       mddev_delayed_delete+0x27/0x30 drivers/md/md.c:5678
       process_one_work+0x867/0xff0 kernel/workqueue.c:2310
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #3 ((work_completion)(&mddev->del_work)){+.+.}-{0:0}:
       process_one_work+0x7ba/0xff0 kernel/workqueue.c:2286
       worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
       kthread+0x42e/0x520 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

-> #2 ((wq_completion)md_misc){+.+.}-{0:0}:
       flush_workqueue+0x16a/0x1390 kernel/workqueue.c:2830
       md_alloc+0x2e/0xc10 drivers/md/md.c:5720
       blk_probe_dev block/genhd.c:685 [inline]
       blk_request_module+0x26e/0x290 block/genhd.c:-1
       blkdev_get_no_open+0x38/0x1d0 block/bdev.c:736
       blkdev_get_by_dev+0x77/0xa50 block/bdev.c:803
       blkdev_open+0x128/0x2c0 block/fops.c:466
       do_dentry_open+0x7f7/0xf90 fs/open.c:826
       do_open fs/namei.c:3616 [inline]
       path_openat+0x2718/0x2fb0 fs/namei.c:3750
       do_filp_open+0x1df/0x400 fs/namei.c:3777
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (major_names_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       blk_probe_dev block/genhd.c:682 [inline]
       blk_request_module+0x31/0x290 block/genhd.c:698
       blkdev_get_no_open+0x38/0x1d0 block/bdev.c:736
       blkdev_get_by_dev+0x77/0xa50 block/bdev.c:803
       lock_rdev drivers/md/md.c:2576 [inline]
       md_import_device+0x3e2/0x810 drivers/md/md.c:3774
       md_add_new_disk+0x3fa/0x1960 drivers/md/md.c:6790
       md_ioctl+0x236f/0x26f0 drivers/md/md.c:7770
       blkdev_ioctl+0x347/0x6f0 block/ioctl.c:604
       block_ioctl+0xac/0xf0 block/fops.c:496
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&mddev->reconfig_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
       lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_interruptible_nested+0x17/0x20 kernel/locking/mutex.c:765
       mddev_lock drivers/md/md.h:543 [inline]
       raid_disks_store+0xb6/0x4f0 drivers/md/md.c:4251
       md_attr_store+0xdd/0x130 drivers/md/md.c:5636
       kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
       call_write_iter include/linux/fs.h:2173 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x748/0xd70 fs/read_write.c:594
       ksys_write+0x153/0x260 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  &mddev->reconfig_mutex --> (work_completion)(&mddev->del_work) --> kn->active#743

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(kn->active#743);
                               lock((work_completion)(&mddev->del_work));
                               lock(kn->active#743);
  lock(&mddev->reconfig_mutex);

 *** DEADLOCK ***

4 locks held by syz.3.1383/9987:
 #0: ffff888077466d70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
 #1: ffff8880621c2460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x296/0xd70 fs/read_write.c:590
 #2: ffff888023001c88 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1dc/0x500 fs/kernfs/file.c:287
 #3: ffff8881445f43a8 (kn->active#743){++++}-{0:0}, at: kernfs_fop_write_iter+0x1fd/0x500 fs/kernfs/file.c:288

stack backtrace:
CPU: 0 PID: 9987 Comm: syz.3.1383 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c66/0x7b50 kernel/locking/lockdep.c:5012
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_interruptible_nested+0x17/0x20 kernel/locking/mutex.c:765
 mddev_lock drivers/md/md.h:543 [inline]
 raid_disks_store+0xb6/0x4f0 drivers/md/md.c:4251
 md_attr_store+0xdd/0x130 drivers/md/md.c:5636
 kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2173 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f16868c20d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1684b1a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1686b49fa0 RCX: 00007f16868c20d9
RDX: 0000000000000001 RSI: 0000200000000380 RDI: 0000000000000003
RBP: 00007f1686959024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1686b4a038 R14: 00007f1686b49fa0 R15: 00007ffd2e670098
 </TASK>