====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.6.5973/26169 is trying to acquire lock: ffff88807e7027c8 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline] ffff88807e7027c8 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: lookup_slow+0x46/0x70 fs/namei.c:1687 but task is already holding lock: ffff88805e4270e0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_free_stale_devices+0x188/0xa90 fs/btrfs/volumes.c:603 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&fs_devs->device_list_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1e3/0x2400 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+0xe2/0xe70 fs/btrfs/volumes.c:7992 commit_cowonly_roots+0x185/0x9c0 fs/btrfs/transaction.c:1292 btrfs_commit_transaction+0x130d/0x3570 fs/btrfs/transaction.c:2394 btrfs_clear_free_space_tree+0x7ad/0xc30 fs/btrfs/free-space-tree.c:1264 btrfs_start_pre_rw_mount+0x287/0x630 fs/btrfs/disk-io.c:3079 open_ctree+0x28c0/0x32b0 fs/btrfs/disk-io.c:3634 btrfs_fill_super+0x1c2/0x2e0 fs/btrfs/super.c:1387 btrfs_mount_root+0x8c7/0x930 fs/btrfs/super.c:1751 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611 vfs_get_tree+0x88/0x270 fs/super.c:1530 fc_mount fs/namespace.c:1005 [inline] vfs_kern_mount+0xba/0x150 fs/namespace.c:1035 btrfs_mount+0x342/0xb10 fs/btrfs/super.c:1811 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611 vfs_get_tree+0x88/0x270 fs/super.c:1530 do_new_mount+0x24a/0xa40 fs/namespace.c:3034 do_mount fs/namespace.c:3377 [inline] __do_sys_mount fs/namespace.c:3585 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562 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 -> #3 (&fs_info->tree_log_mutex){+.+.}-{3:3}: __lock_release kernel/locking/lockdep.c:5339 [inline] lock_release+0x321/0x8a0 kernel/locking/lockdep.c:5643 __mutex_unlock_slowpath+0xc8/0x6c0 kernel/locking/mutex.c:851 btrfs_commit_transaction+0x1d11/0x3570 fs/btrfs/transaction.c:2441 btrfs_clear_free_space_tree+0x7ad/0xc30 fs/btrfs/free-space-tree.c:1264 btrfs_start_pre_rw_mount+0x287/0x630 fs/btrfs/disk-io.c:3079 open_ctree+0x28c0/0x32b0 fs/btrfs/disk-io.c:3634 btrfs_fill_super+0x1c2/0x2e0 fs/btrfs/super.c:1387 btrfs_mount_root+0x8c7/0x930 fs/btrfs/super.c:1751 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611 vfs_get_tree+0x88/0x270 fs/super.c:1530 fc_mount fs/namespace.c:1005 [inline] vfs_kern_mount+0xba/0x150 fs/namespace.c:1035 btrfs_mount+0x342/0xb10 fs/btrfs/super.c:1811 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611 vfs_get_tree+0x88/0x270 fs/super.c:1530 do_new_mount+0x24a/0xa40 fs/namespace.c:3034 do_mount fs/namespace.c:3377 [inline] __do_sys_mount fs/namespace.c:3585 [inline] __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562 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 -> #2 (sb_internal#3){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1811 [inline] sb_start_intwrite include/linux/fs.h:1928 [inline] start_transaction+0x5bc/0x1130 fs/btrfs/transaction.c:680 btrfs_dirty_inode+0xc5/0x1c0 fs/btrfs/inode.c:6451 inode_update_time fs/inode.c:1893 [inline] touch_atime+0x2f8/0x640 fs/inode.c:1966 file_accessed include/linux/fs.h:2522 [inline] btrfs_file_mmap+0xc1/0x120 fs/btrfs/file.c:2449 call_mmap include/linux/fs.h:2178 [inline] mmap_file+0x5d/0xb0 mm/util.c:1092 __mmap_region mm/mmap.c:1796 [inline] mmap_region+0xf88/0x1650 mm/mmap.c:2933 do_mmap+0x819/0xe90 mm/mmap.c:1586 vm_mmap_pgoff+0x1c1/0x2d0 mm/util.c:551 ksys_mmap_pgoff+0x54b/0x790 mm/mmap.c:1635 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 (&mm->mmap_lock){++++}-{3:3}: down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498 mmap_read_lock+0x1c/0x50 include/linux/mmap_lock.h:117 do_user_addr_fault+0xc35/0xc80 arch/x86/mm/fault.c:1308 handle_page_fault arch/x86/mm/fault.c:1445 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1501 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 user_access_begin arch/x86/include/asm/uaccess.h:576 [inline] filldir+0x300/0x720 fs/readdir.c:249 dir_emit_dot include/linux/fs.h:3718 [inline] dir_emit_dots include/linux/fs.h:3729 [inline] dcache_readdir+0x173/0x7c0 fs/libfs.c:196 iterate_dir+0x218/0x560 fs/readdir.c:-1 __do_sys_getdents fs/readdir.c:286 [inline] __se_sys_getdents+0xf2/0x260 fs/readdir.c:271 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#3){++++}-{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+0x2c42/0x7d10 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 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+0x214/0x540 fs/namei.c:2492 kern_path+0x37/0x190 fs/namei.c:2590 lookup_bdev+0xc5/0x280 block/bdev.c:982 device_matched fs/btrfs/volumes.c:568 [inline] btrfs_free_stale_devices+0x6ec/0xa90 fs/btrfs/volumes.c:608 btrfs_forget_devices+0x52/0x80 fs/btrfs/volumes.c:1431 btrfs_control_ioctl+0x10a/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#3 --> &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#3); *** DEADLOCK *** 2 locks held by syz.6.5973/26169: #0: ffffffff8c808928 (uuid_mutex){+.+.}-{3:3}, at: btrfs_forget_devices+0x1a/0x80 fs/btrfs/volumes.c:1430 #1: ffff88805e4270e0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_free_stale_devices+0x188/0xa90 fs/btrfs/volumes.c:603 stack backtrace: CPU: 1 PID: 26169 Comm: syz.6.5973 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: 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+0x2c42/0x7d10 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 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+0x214/0x540 fs/namei.c:2492 kern_path+0x37/0x190 fs/namei.c:2590 lookup_bdev+0xc5/0x280 block/bdev.c:982 device_matched fs/btrfs/volumes.c:568 [inline] btrfs_free_stale_devices+0x6ec/0xa90 fs/btrfs/volumes.c:608 btrfs_forget_devices+0x52/0x80 fs/btrfs/volumes.c:1431 btrfs_control_ioctl+0x10a/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: 0033:0x7f99becffeb9 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:00007f99bcf3a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f99bef7b090 RCX: 00007f99becffeb9 RDX: 00002000000001c0 RSI: 0000000050009405 RDI: 0000000000000006 RBP: 00007f99bed6dc1f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f99bef7b128 R14: 00007f99bef7b090 R15: 00007ffdfbf8b088