====================================================== WARNING: possible circular locking dependency detected 6.1.127-syzkaller #0 Not tainted ------------------------------------------------------ udevd/4848 is trying to acquire lock: ffff0000c04a0e08 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:768 [inline] ffff0000c04a0e08 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: lookup_slow+0x50/0x84 fs/namei.c:1706 but task is already holding lock: ffff0000f36fece0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: device_list_add+0x6e8/0x1d08 fs/btrfs/volumes.c:860 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #6 (&fs_devs->device_list_mutex){+.+.}-{3:3}: __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 btrfs_run_dev_stats+0xf4/0xea4 fs/btrfs/volumes.c:8058 commit_cowonly_roots+0x1a4/0x740 fs/btrfs/transaction.c:1295 btrfs_commit_transaction+0x1228/0x2cd4 fs/btrfs/transaction.c:2425 btrfs_rebuild_free_space_tree+0x2e8/0x6dc fs/btrfs/free-space-tree.c:1338 btrfs_start_pre_rw_mount+0x2cc/0x65c fs/btrfs/disk-io.c:3238 open_ctree+0x1e40/0x2340 fs/btrfs/disk-io.c:3835 btrfs_fill_super+0x1b4/0x2c8 fs/btrfs/super.c:1469 btrfs_mount_root+0x6f8/0x7f8 fs/btrfs/super.c:1835 legacy_get_tree+0xd4/0x16c fs/fs_context.c:632 vfs_get_tree+0x90/0x274 fs/super.c:1573 fc_mount fs/namespace.c:1043 [inline] vfs_kern_mount+0xdc/0x178 fs/namespace.c:1073 btrfs_mount+0x330/0x9c8 fs/btrfs/super.c:1895 legacy_get_tree+0xd4/0x16c fs/fs_context.c:632 vfs_get_tree+0x90/0x274 fs/super.c:1573 do_new_mount+0x278/0x8fc fs/namespace.c:3056 path_mount+0x590/0xe5c fs/namespace.c:3386 do_mount fs/namespace.c:3399 [inline] __do_sys_mount fs/namespace.c:3607 [inline] __se_sys_mount fs/namespace.c:3584 [inline] __arm64_sys_mount+0x45c/0x594 fs/namespace.c:3584 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #5 (&fs_info->reloc_mutex){+.+.}-{3:3}: __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 btrfs_record_root_in_trans fs/btrfs/transaction.c:486 [inline] start_transaction+0x47c/0x1110 fs/btrfs/transaction.c:728 btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:764 btrfs_create_common+0x198/0x2b8 fs/btrfs/inode.c:6778 btrfs_create+0x104/0x128 fs/btrfs/inode.c:6824 lookup_open fs/namei.c:3482 [inline] open_last_lookups fs/namei.c:3550 [inline] path_openat+0xeac/0x2548 fs/namei.c:3780 do_filp_open+0x1bc/0x3cc fs/namei.c:3810 do_sys_openat2+0x128/0x3e0 fs/open.c:1318 do_sys_open fs/open.c:1334 [inline] __do_sys_openat fs/open.c:1350 [inline] __se_sys_openat fs/open.c:1345 [inline] __arm64_sys_openat+0x1f0/0x240 fs/open.c:1345 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #4 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x194/0xb6c fs/btrfs/transaction.c:301 start_transaction+0x7b8/0x1110 fs/btrfs/transaction.c:665 btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:764 btrfs_rebuild_free_space_tree+0xb4/0x6dc fs/btrfs/free-space-tree.c:1311 btrfs_start_pre_rw_mount+0x2cc/0x65c fs/btrfs/disk-io.c:3238 open_ctree+0x1e40/0x2340 fs/btrfs/disk-io.c:3835 btrfs_fill_super+0x1b4/0x2c8 fs/btrfs/super.c:1469 btrfs_mount_root+0x6f8/0x7f8 fs/btrfs/super.c:1835 legacy_get_tree+0xd4/0x16c fs/fs_context.c:632 vfs_get_tree+0x90/0x274 fs/super.c:1573 fc_mount fs/namespace.c:1043 [inline] vfs_kern_mount+0xdc/0x178 fs/namespace.c:1073 btrfs_mount+0x330/0x9c8 fs/btrfs/super.c:1895 legacy_get_tree+0xd4/0x16c fs/fs_context.c:632 vfs_get_tree+0x90/0x274 fs/super.c:1573 do_new_mount+0x278/0x8fc fs/namespace.c:3056 path_mount+0x590/0xe5c fs/namespace.c:3386 do_mount fs/namespace.c:3399 [inline] __do_sys_mount fs/namespace.c:3607 [inline] __se_sys_mount fs/namespace.c:3584 [inline] __arm64_sys_mount+0x45c/0x594 fs/namespace.c:3584 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #3 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5376 [inline] lock_release+0x364/0xa50 kernel/locking/lockdep.c:5682 percpu_up_read include/linux/percpu-rwsem.h:99 [inline] __sb_end_write include/linux/fs.h:1886 [inline] sb_end_intwrite+0x58/0x3fc include/linux/fs.h:1942 __btrfs_end_transaction+0x314/0x75c fs/btrfs/transaction.c:1015 btrfs_end_transaction+0x24/0x34 fs/btrfs/transaction.c:1049 btrfs_dirty_inode+0x188/0x1c0 fs/btrfs/inode.c:6284 btrfs_update_time+0x170/0x18c fs/btrfs/inode.c:6312 inode_update_time fs/inode.c:1958 [inline] __file_update_time+0xc0/0x21c fs/inode.c:2147 file_update_time+0x2cc/0x348 fs/inode.c:2178 btrfs_page_mkwrite+0x3fc/0xcac fs/btrfs/inode.c:8597 do_page_mkwrite+0x144/0x37c mm/memory.c:3009 wp_page_shared+0x148/0x550 mm/memory.c:3358 do_wp_page+0xcbc/0xf44 mm/memory.c:3508 handle_pte_fault mm/memory.c:5047 [inline] __handle_mm_fault mm/memory.c:5171 [inline] handle_mm_fault+0x19a4/0x3d38 mm/memory.c:5292 __do_page_fault arch/arm64/mm/fault.c:499 [inline] do_page_fault+0x330/0x890 arch/arm64/mm/fault.c:583 do_mem_abort+0x74/0x200 arch/arm64/mm/fault.c:803 el0_da+0x70/0x184 arch/arm64/kernel/entry-common.c:515 el0t_64_sync_handler+0xcc/0xf0 arch/arm64/kernel/entry-common.c:658 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #2 (sb_pagefaults#2){.+.+}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1891 [inline] sb_start_pagefault include/linux/fs.h:1995 [inline] btrfs_page_mkwrite+0x1dc/0xcac fs/btrfs/inode.c:8581 do_page_mkwrite+0x144/0x37c mm/memory.c:3009 wp_page_shared+0x148/0x550 mm/memory.c:3358 do_wp_page+0xcbc/0xf44 mm/memory.c:3508 handle_pte_fault mm/memory.c:5047 [inline] __handle_mm_fault mm/memory.c:5171 [inline] handle_mm_fault+0x19a4/0x3d38 mm/memory.c:5292 __do_page_fault arch/arm64/mm/fault.c:499 [inline] do_page_fault+0x330/0x890 arch/arm64/mm/fault.c:583 do_mem_abort+0x74/0x200 arch/arm64/mm/fault.c:803 el0_da+0x70/0x184 arch/arm64/kernel/entry-common.c:515 el0t_64_sync_handler+0xcc/0xf0 arch/arm64/kernel/entry-common.c:658 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #1 (&mm->mmap_lock){++++}-{3:3}: __might_fault+0xc4/0x124 mm/memory.c:5851 filldir64+0x2d4/0x948 fs/readdir.c:335 dir_emit include/linux/fs.h:3693 [inline] call_filldir fs/ext4/dir.c:544 [inline] ext4_dx_readdir fs/ext4/dir.c:620 [inline] ext4_readdir+0x2ba4/0x3388 fs/ext4/dir.c:142 iterate_dir+0x1f4/0x4ec __do_sys_getdents64 fs/readdir.c:369 [inline] __se_sys_getdents64 fs/readdir.c:354 [inline] __arm64_sys_getdents64+0x1c4/0x4a0 fs/readdir.c:354 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #0 (&type->i_mutex_dir_key#3){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 down_read+0x64/0x308 kernel/locking/rwsem.c:1520 inode_lock_shared include/linux/fs.h:768 [inline] lookup_slow+0x50/0x84 fs/namei.c:1706 walk_component+0x280/0x36c fs/namei.c:1998 lookup_last fs/namei.c:2455 [inline] path_lookupat+0x13c/0x3d0 fs/namei.c:2479 filename_lookup+0x1d4/0x4e0 fs/namei.c:2508 kern_path+0x48/0x6c fs/namei.c:2606 is_same_device fs/btrfs/volumes.c:695 [inline] device_list_add+0x1258/0x1d08 fs/btrfs/volumes.c:928 btrfs_scan_one_device+0x3c8/0x61c fs/btrfs/volumes.c:1461 btrfs_control_ioctl+0x144/0x388 fs/btrfs/super.c:2519 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 other info that might help us debug this: Chain exists of: &type->i_mutex_dir_key#3 --> &fs_info->reloc_mutex --> &fs_devs->device_list_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fs_devs->device_list_mutex); lock(&fs_info->reloc_mutex); lock(&fs_devs->device_list_mutex); lock(&type->i_mutex_dir_key#3); *** DEADLOCK *** 2 locks held by udevd/4848: #0: ffff800016197508 (uuid_mutex){+.+.}-{3:3}, at: btrfs_control_ioctl+0x130/0x388 fs/btrfs/super.c:2518 #1: ffff0000f36fece0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: device_list_add+0x6e8/0x1d08 fs/btrfs/volumes.c:860 stack backtrace: CPU: 0 PID: 4848 Comm: udevd Not tainted 6.1.127-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2048 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 down_read+0x64/0x308 kernel/locking/rwsem.c:1520 inode_lock_shared include/linux/fs.h:768 [inline] lookup_slow+0x50/0x84 fs/namei.c:1706 walk_component+0x280/0x36c fs/namei.c:1998 lookup_last fs/namei.c:2455 [inline] path_lookupat+0x13c/0x3d0 fs/namei.c:2479 filename_lookup+0x1d4/0x4e0 fs/namei.c:2508 kern_path+0x48/0x6c fs/namei.c:2606 is_same_device fs/btrfs/volumes.c:695 [inline] device_list_add+0x1258/0x1d08 fs/btrfs/volumes.c:928 btrfs_scan_one_device+0x3c8/0x61c fs/btrfs/volumes.c:1461 btrfs_control_ioctl+0x144/0x388 fs/btrfs/super.c:2519 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 BTRFS info: devid 1 device path file0 changed to /dev/loop3 scanned by udevd (4848)