netlink: 20 bytes leftover after parsing attributes in process `syz-executor.3'.
block nbd5: shutting down sockets
======================================================
WARNING: possible circular locking dependency detected
4.14.307-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.5/11723 is trying to acquire lock:
 (&bdev->bd_mutex){+.+.}, at: [<ffffffff830c548b>] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192

but task is already holding lock:
 (&nbd->config_lock){+.+.}, at: [<ffffffff838e839f>] nbd_ioctl+0x11f/0xad0 drivers/block/nbd.c:1369
BTRFS: device fsid a6a605fc-d5f1-4e66-8595-3726e2b761d6 

which lock already depends on the new lock.

devid 1 transid 8 /dev/loop2

the existing dependency chain (in reverse order) is:

-> #2 (&nbd->config_lock){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       nbd_open+0x1ac/0x370 drivers/block/nbd.c:1422
       __blkdev_get+0x306/0x1090 fs/block_dev.c:1470
       blkdev_get+0x88/0x890 fs/block_dev.c:1611
       blkdev_open+0x1cc/0x250 fs/block_dev.c:1772
       do_dentry_open+0x44b/0xec0 fs/open.c:777
       vfs_open+0x105/0x220 fs/open.c:888
       do_last fs/namei.c:3428 [inline]
       path_openat+0x628/0x2970 fs/namei.c:3571
       do_filp_open+0x179/0x3c0 fs/namei.c:3605
       do_sys_open+0x296/0x410 fs/open.c:1081
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x5e/0xd3

-> #1 (nbd_index_mutex){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       nbd_open+0x1e/0x370 drivers/block/nbd.c:1409
       __blkdev_get+0x306/0x1090 fs/block_dev.c:1470
       blkdev_get+0x88/0x890 fs/block_dev.c:1611
       blkdev_open+0x1cc/0x250 fs/block_dev.c:1772
       do_dentry_open+0x44b/0xec0 fs/open.c:777
       vfs_open+0x105/0x220 fs/open.c:888
       do_last fs/namei.c:3428 [inline]
       path_openat+0x628/0x2970 fs/namei.c:3571
       do_filp_open+0x179/0x3c0 fs/namei.c:3605
       do_sys_open+0x296/0x410 fs/open.c:1081
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x5e/0xd3

-> #0 (&bdev->bd_mutex){+.+.}:
       lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
       nbd_bdev_reset drivers/block/nbd.c:1076 [inline]
       nbd_clear_sock_ioctl drivers/block/nbd.c:1282 [inline]
       __nbd_ioctl drivers/block/nbd.c:1306 [inline]
       nbd_ioctl+0x802/0xad0 drivers/block/nbd.c:1376
       __blkdev_driver_ioctl block/ioctl.c:297 [inline]
       blkdev_ioctl+0x540/0x1830 block/ioctl.c:594
       block_ioctl+0xd9/0x120 fs/block_dev.c:1893
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:500 [inline]
       do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
       SYSC_ioctl fs/ioctl.c:701 [inline]
       SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x5e/0xd3

other info that might help us debug this:

Chain exists of:
  &bdev->bd_mutex --> nbd_index_mutex --> &nbd->config_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&nbd->config_lock);
                               lock(nbd_index_mutex);
                               lock(&nbd->config_lock);
  lock(&bdev->bd_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor.5/11723:
 #0:  (&nbd->config_lock){+.+.}, at: [<ffffffff838e839f>] nbd_ioctl+0x11f/0xad0 drivers/block/nbd.c:1369

stack backtrace:
CPU: 1 PID: 11723 Comm: syz-executor.5 Not tainted 4.14.307-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1905 [inline]
 check_prevs_add kernel/locking/lockdep.c:2022 [inline]
 validate_chain kernel/locking/lockdep.c:2464 [inline]
 __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 __mutex_lock_common kernel/locking/mutex.c:756 [inline]
 __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192
 nbd_bdev_reset drivers/block/nbd.c:1076 [inline]
 nbd_clear_sock_ioctl drivers/block/nbd.c:1282 [inline]
 __nbd_ioctl drivers/block/nbd.c:1306 [inline]
 nbd_ioctl+0x802/0xad0 drivers/block/nbd.c:1376
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x540/0x1830 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1893
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x5e/0xd3
RIP: 0033:0x7f63abbab0f9
RSP: 002b:00007f63aa0fc168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f63abccb050 RCX: 00007f63abbab0f9
RDX: 0000000000000000 RSI: 000000000000ab04 RDI: 0000000000000004
RBP: 00007f63abc06ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe1dbd770f R14: 00007f63aa0fc300 R15: 0000000000022000
BTRFS error (device loop2): unsupported checksum algorithm 3
BTRFS error (device loop2): superblock checksum mismatch
BTRFS error (device loop2): open_ctree failed
netlink: 20 bytes leftover after parsing attributes in process `syz-executor.3'.
netlink: 12 bytes leftover after parsing attributes in process `syz-executor.1'.
bond1: Enslaving bridge1 as an active interface with an up link
bond1 (unregistering): Releasing backup interface bridge1
BTRFS error (device loop2): unsupported checksum algorithm 3
BTRFS error (device loop2): superblock checksum mismatch
bond1 (unregistering): Released all slaves
BTRFS error (device loop2): open_ctree failed
print_req_error: I/O error, dev loop4, sector 0
XFS (loop0): unknown mount option [nolazytime].
netlink: 20 bytes leftover after parsing attributes in process `syz-executor.3'.
BTRFS error (device loop2): unsupported checksum algorithm 3
BTRFS error (device loop2): superblock checksum mismatch
BTRFS error (device loop2): open_ctree failed
NILFS (loop0): invalid segment: Checksum error in segment payload
NILFS (loop0): trying rollback from an earlier position
NILFS (loop0): recovery complete
NILFS (loop0): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds
audit: type=1800 audit(1677920369.051:2): pid=12003 uid=0 auid=4294967295 ses=4294967295 op="collect_data" cause="failed(directio)" comm="syz-executor.0" name="bus" dev="loop0" ino=12 res=0
audit: type=1800 audit(1677920369.051:3): pid=12003 uid=0 auid=4294967295 ses=4294967295 op="collect_data" cause="failed(directio)" comm="syz-executor.0" name="bus" dev="loop0" ino=12 res=0
BTRFS error (device loop2): unsupported checksum algorithm 3
BTRFS error (device loop2): superblock checksum mismatch
BTRFS error (device loop2): open_ctree failed
unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.3'.
netlink: 4320 bytes leftover after parsing attributes in process `syz-executor.1'.
netlink: 164 bytes leftover after parsing attributes in process `syz-executor.3'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.2'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor.5'.
netlink: 232 bytes leftover after parsing attributes in process `syz-executor.1'.
batadv0: Invalid MTU 0 requested, hw min 68
netlink: 180 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 164 bytes leftover after parsing attributes in process `syz-executor.4'.
netlink: 156 bytes leftover after parsing attributes in process `syz-executor.3'.