XFS (loop7): Unmounting Filesystem ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor/6527 is trying to acquire lock: ffff888024b7b4c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf7/0x780 block/bdev.c:930 but task is already holding lock: ffff8880245400e0 (&type->s_umount_key#59){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&type->s_umount_key#59){++++}-{3:3}: down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520 get_super+0x102/0x200 fs/super.c:828 __invalidate_device+0x19/0xf0 block/bdev.c:1022 nbd_clear_sock_ioctl drivers/block/nbd.c:1463 [inline] __nbd_ioctl drivers/block/nbd.c:1490 [inline] nbd_ioctl+0x368/0xed0 drivers/block/nbd.c:1550 blkdev_ioctl+0x37b/0x740 block/ioctl.c:626 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #1 (&nbd->config_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 refcount_dec_and_mutex_lock+0x2c/0xa0 lib/refcount.c:118 nbd_config_put+0x2c/0x760 drivers/block/nbd.c:1328 nbd_release+0xfa/0x130 drivers/block/nbd.c:1632 blkdev_put+0x5b4/0x780 block/bdev.c:-1 blkdev_close+0x51/0x80 block/fops.c:514 __fput+0x20a/0x8b0 fs/file_table.c:320 task_work_run+0x1d0/0x260 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (&disk->open_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 blkdev_put+0xf7/0x780 block/bdev.c:930 xfs_close_devices+0xf3/0x130 fs/xfs/xfs_super.c:409 xfs_fs_put_super+0x242/0x2c0 fs/xfs/xfs_super.c:1126 generic_shutdown_super+0x130/0x340 fs/super.c:501 kill_block_super+0x7c/0xe0 fs/super.c:1470 deactivate_locked_super+0x93/0xf0 fs/super.c:332 cleanup_mnt+0x471/0x4f0 fs/namespace.c:1191 task_work_run+0x1d0/0x260 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Chain exists of: &disk->open_mutex --> &nbd->config_lock --> &type->s_umount_key#59 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&type->s_umount_key#59); lock(&nbd->config_lock); lock(&type->s_umount_key#59); lock(&disk->open_mutex); *** DEADLOCK *** 1 lock held by syz-executor/6527: #0: ffff8880245400e0 (&type->s_umount_key#59){++++}-{3:3}, at: deactivate_super+0xa0/0xd0 fs/super.c:362 stack backtrace: CPU: 1 PID: 6527 Comm: syz-executor Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3830 [inline] __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5676 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747 blkdev_put+0xf7/0x780 block/bdev.c:930 xfs_close_devices+0xf3/0x130 fs/xfs/xfs_super.c:409 xfs_fs_put_super+0x242/0x2c0 fs/xfs/xfs_super.c:1126 generic_shutdown_super+0x130/0x340 fs/super.c:501 kill_block_super+0x7c/0xe0 fs/super.c:1470 deactivate_locked_super+0x93/0xf0 fs/super.c:332 cleanup_mnt+0x471/0x4f0 fs/namespace.c:1191 task_work_run+0x1d0/0x260 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fc0ce19f097 Code: a2 c7 05 5c 26 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 RSP: 002b:00007ffc047c0a88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000064 RCX: 00007fc0ce19f097 RDX: 0000000000000200 RSI: 0000000000000009 RDI: 00007ffc047c1c30 RBP: 00007fc0ce2332ca R08: 0000000000020590 R09: 00000000ffffffff R10: 0000000000000100 R11: 0000000000000202 R12: 00007ffc047c1c30 R13: 00007fc0ce2332ca R14: 00005555559504e8 R15: 00007ffc047c2d00 BTRFS info (device loop7): last unmount of filesystem c9fe44da-de57-406a-8241-57ec7d4412cf