BTRFS info (device loop6): clearing free space tree BTRFS info (device loop6): clearing compat-ro feature flag for FREE_SPACE_TREE (0x1) BTRFS info (device loop6): clearing compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2) ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.6.182/5564 is trying to acquire lock: ffff888073ebd490 (&type->i_mutex_dir_key#15){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline] ffff888073ebd490 (&type->i_mutex_dir_key#15){++++}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1687 but task is already holding lock: ffff88805f2754e0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_free_stale_devices+0x186/0xa60 fs/btrfs/volumes.c:603 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&fs_devs->device_list_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1eb/0x2390 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 btrfs_run_dev_stats+0xdf/0xdf0 fs/btrfs/volumes.c:7991 commit_cowonly_roots+0x17e/0x9c0 fs/btrfs/transaction.c:1292 btrfs_commit_transaction+0x1229/0x3440 fs/btrfs/transaction.c:2394 close_ctree+0x3d5/0x8c0 fs/btrfs/disk-io.c:4470 generic_shutdown_super+0x130/0x300 fs/super.c:475 kill_anon_super+0x36/0x70 fs/super.c:1089 btrfs_kill_super+0x3d/0x50 fs/btrfs/super.c:2390 deactivate_locked_super+0x93/0xf0 fs/super.c:335 cleanup_mnt+0x418/0x4d0 fs/namespace.c:1148 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #2 (&fs_info->tree_log_mutex){+.+.}-{3:3}: __lock_release kernel/locking/lockdep.c:5339 [inline] lock_release+0x31a/0x870 kernel/locking/lockdep.c:5643 __mutex_unlock_slowpath+0xb3/0x6a0 kernel/locking/mutex.c:851 btrfs_commit_transaction+0x1c11/0x3440 fs/btrfs/transaction.c:2441 close_ctree+0x3d5/0x8c0 fs/btrfs/disk-io.c:4470 generic_shutdown_super+0x130/0x300 fs/super.c:475 kill_anon_super+0x36/0x70 fs/super.c:1089 btrfs_kill_super+0x3d/0x50 fs/btrfs/super.c:2390 deactivate_locked_super+0x93/0xf0 fs/super.c:335 cleanup_mnt+0x418/0x4d0 fs/namespace.c:1148 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #1 (sb_internal#4){.+.+}-{0:0}: __lock_release kernel/locking/lockdep.c:5339 [inline] lock_release+0x31a/0x870 kernel/locking/lockdep.c:5643 up_write+0x29/0x420 kernel/locking/rwsem.c:1603 btrfs_inode_unlock+0x37/0x70 fs/btrfs/inode.c:140 btrfs_sync_file+0xb33/0x10d0 fs/btrfs/file.c:2362 vfs_fsync_range fs/sync.c:188 [inline] vfs_fsync fs/sync.c:202 [inline] do_fsync fs/sync.c:212 [inline] __do_sys_fsync fs/sync.c:220 [inline] __se_sys_fsync fs/sync.c:218 [inline] __x64_sys_fsync+0x1a5/0x1e0 fs/sync.c:218 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 (&type->i_mutex_dir_key#15){++++}-{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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623 down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498 inode_lock_shared include/linux/fs.h:797 [inline] lookup_slow+0x46/0x70 fs/namei.c:1687 walk_component+0x319/0x460 fs/namei.c:1984 lookup_last fs/namei.c:2439 [inline] path_lookupat+0x169/0x440 fs/namei.c:2463 filename_lookup+0x1e2/0x4f0 fs/namei.c:2492 kern_path+0x37/0x190 fs/namei.c:2590 lookup_bdev+0xbd/0x270 block/bdev.c:982 device_matched fs/btrfs/volumes.c:568 [inline] btrfs_free_stale_devices+0x6db/0xa60 fs/btrfs/volumes.c:608 btrfs_forget_devices+0x52/0x80 fs/btrfs/volumes.c:1431 btrfs_control_ioctl+0x104/0x220 fs/btrfs/super.c:2450 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 other info that might help us debug this: Chain exists of: &type->i_mutex_dir_key#15 --> &fs_info->tree_log_mutex --> &fs_devs->device_list_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fs_devs->device_list_mutex); lock(&fs_info->tree_log_mutex); lock(&fs_devs->device_list_mutex); lock(&type->i_mutex_dir_key#15); *** DEADLOCK *** 2 locks held by syz.6.182/5564: #0: ffffffff8c606668 (uuid_mutex){+.+.}-{3:3}, at: btrfs_forget_devices+0x1a/0x80 fs/btrfs/volumes.c:1430 #1: ffff88805f2754e0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_free_stale_devices+0x186/0xa60 fs/btrfs/volumes.c:603 stack backtrace: CPU: 1 PID: 5564 Comm: syz.6.182 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 check_noncircular+0x274/0x310 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+0x2c33/0x7c60 kernel/locking/lockdep.c:5012 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623 down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498 inode_lock_shared include/linux/fs.h:797 [inline] lookup_slow+0x46/0x70 fs/namei.c:1687 walk_component+0x319/0x460 fs/namei.c:1984 lookup_last fs/namei.c:2439 [inline] path_lookupat+0x169/0x440 fs/namei.c:2463 filename_lookup+0x1e2/0x4f0 fs/namei.c:2492 kern_path+0x37/0x190 fs/namei.c:2590 lookup_bdev+0xbd/0x270 block/bdev.c:982 device_matched fs/btrfs/volumes.c:568 [inline] btrfs_free_stale_devices+0x6db/0xa60 fs/btrfs/volumes.c:608 btrfs_forget_devices+0x52/0x80 fs/btrfs/volumes.c:1431 btrfs_control_ioctl+0x104/0x220 fs/btrfs/super.c:2450 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 RIP: 0033:0x7fc52bf9d749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc52a204038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fc52c1f3fa0 RCX: 00007fc52bf9d749 RDX: 0000200000000180 RSI: 0000000050009405 RDI: 0000000000000008 RBP: 00007fc52c021f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc52c1f4038 R14: 00007fc52c1f3fa0 R15: 00007ffc6204afd8