md: loop0 has zero or unknown size, marking faulty!
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.99/6213 is trying to acquire lock:
ffff88807ac32358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: mddev_lock drivers/md/md.h:713 [inline]
ffff88807ac32358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: mddev_suspend_and_lock drivers/md/md.h:1019 [inline]
ffff88807ac32358 (&mddev->reconfig_mutex){+.+.}-{4:4}, at: location_store+0xc6/0xc80 drivers/md/md-bitmap.c:2636

but task is already holding lock:
ffff8880788b1698 (kn->active#67){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
ffff8880788b1698 (kn->active#67){++++}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540 fs/kernfs/file.c:337

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (kn->active#67){++++}-{0:0}:
       kernfs_drain+0x293/0x640 fs/kernfs/dir.c:532
       __kernfs_remove+0x493/0x8e0 fs/kernfs/dir.c:1565
       kernfs_remove_by_name_ns+0xc0/0x140 fs/kernfs/dir.c:1783
       kernfs_remove_by_name include/linux/kernfs.h:644 [inline]
       remove_files fs/sysfs/group.c:28 [inline]
       sysfs_remove_group+0x101/0x2e0 fs/sysfs/group.c:328
       md_bitmap_sysfs_del drivers/md/md.c:707 [inline]
       md_bitmap_destroy drivers/md/md.c:6635 [inline]
       __md_stop+0x22a/0x3a0 drivers/md/md.c:7089
       do_md_stop+0x2e2/0x1150 drivers/md/md.c:7193
       array_state_store+0x802/0xe90 drivers/md/md.c:4713
       md_attr_store+0x3b7/0x640 drivers/md/md.c:6158
       kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x612/0xba0 fs/read_write.c:687
       ksys_write+0x150/0x270 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&mddev->reconfig_mutex){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3181 [inline]
       check_prevs_add kernel/locking/lockdep.c:3300 [inline]
       validate_chain kernel/locking/lockdep.c:3924 [inline]
       __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254
       lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x19c/0x15a0 kernel/locking/mutex.c:821
       mddev_lock drivers/md/md.h:713 [inline]
       mddev_suspend_and_lock drivers/md/md.h:1019 [inline]
       location_store+0xc6/0xc80 drivers/md/md-bitmap.c:2636
       md_attr_store+0x3b7/0x640 drivers/md/md.c:6158
       kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x612/0xba0 fs/read_write.c:687
       ksys_write+0x150/0x270 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(kn->active#67);
                               lock(&mddev->reconfig_mutex);
                               lock(kn->active#67);
  lock(&mddev->reconfig_mutex);

 *** DEADLOCK ***

locks held by syz.4.99/6213: 4, last CPU#0:
 #0: ffff88807aac3eb0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
 #1: ffff888034d9c460 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
 #1: ffff888034d9c460 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
 #2: ffff88807ab7f080 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336
 #3: ffff8880788b1698 (kn->active#67){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #3: ffff8880788b1698 (kn->active#67){++++}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540 fs/kernfs/file.c:337

stack backtrace:
CPU: 0 UID: 0 PID: 6213 Comm: syz.4.99 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2059
 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2191
 check_prev_add kernel/locking/lockdep.c:3181 [inline]
 check_prevs_add kernel/locking/lockdep.c:3300 [inline]
 validate_chain kernel/locking/lockdep.c:3924 [inline]
 __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254
 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x19c/0x15a0 kernel/locking/mutex.c:821
 mddev_lock drivers/md/md.h:713 [inline]
 mddev_suspend_and_lock drivers/md/md.h:1019 [inline]
 location_store+0xc6/0xc80 drivers/md/md-bitmap.c:2636
 md_attr_store+0x3b7/0x640 drivers/md/md.c:6158
 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f34abf9e159
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:00007f34acd9d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f34ac225fa0 RCX: 00007f34abf9e159
RDX: 0000000000000003 RSI: 0000200000000540 RDI: 0000000000000009
RBP: 00007f34ac035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f34ac226038 R14: 00007f34ac225fa0 R15: 00007fff72b5b2d8
 </TASK>