====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor/4584 is trying to acquire lock: ffff0000f03cace0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_run_dev_stats+0xe8/0xd2c fs/btrfs/volumes.c:7998 but task is already holding lock: ffff0000d5a90720 (&fs_info->tree_log_mutex){+.+.}-{3:3}, at: btrfs_commit_transaction+0xea8/0x30ac fs/btrfs/transaction.c:2370 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&fs_info->tree_log_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1a4/0x1ea4 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 btrfs_commit_transaction+0xea8/0x30ac fs/btrfs/transaction.c:2370 btrfs_sync_fs+0x240/0xb2c fs/btrfs/super.c:1454 sync_filesystem+0x1a0/0x218 fs/sync.c:66 generic_shutdown_super+0x74/0x2f8 fs/super.c:448 kill_anon_super+0x4c/0x80 fs/super.c:1089 btrfs_kill_super+0x44/0x5c fs/btrfs/super.c:2390 deactivate_locked_super+0xc0/0x13c fs/super.c:335 deactivate_super+0xf0/0x110 fs/super.c:366 cleanup_mnt+0x3bc/0x470 fs/namespace.c:1148 __cleanup_mnt+0x20/0x30 fs/namespace.c:1155 task_work_run+0x13c/0x1e8 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] do_notify_resume+0x2488/0x30a8 arch/arm64/kernel/signal.c:949 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xf0/0x1d0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #4 (&fs_info->reloc_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1a4/0x1ea4 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 btrfs_record_root_in_trans fs/btrfs/transaction.c:513 [inline] start_transaction+0x49c/0x1438 fs/btrfs/transaction.c:751 btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:780 btrfs_create+0xf4/0x50c fs/btrfs/inode.c:6919 lookup_open fs/namei.c:3470 [inline] open_last_lookups fs/namei.c:3540 [inline] path_openat+0xdb8/0x2808 fs/namei.c:3747 do_filp_open+0x188/0x370 fs/namei.c:3777 do_sys_openat2+0x134/0x3fc fs/open.c:1255 do_sys_open fs/open.c:1271 [inline] __do_sys_openat fs/open.c:1287 [inline] __se_sys_openat fs/open.c:1282 [inline] __arm64_sys_openat+0x11c/0x150 fs/open.c:1282 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x28c arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x5c/0x140 arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #3 (sb_internal#2){.+.+}-{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+0x684/0x1438 fs/btrfs/transaction.c:681 btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:794 btrfs_dirty_inode+0xb0/0x1b8 fs/btrfs/inode.c:6455 btrfs_update_time+0x21c/0x240 fs/btrfs/inode.c:6497 inode_update_time fs/inode.c:1893 [inline] touch_atime+0x3d0/0x918 fs/inode.c:1966 file_accessed include/linux/fs.h:2522 [inline] btrfs_file_mmap+0xb0/0x11c fs/btrfs/file.c:2449 call_mmap include/linux/fs.h:2178 [inline] mmap_file+0x6c/0xc8 mm/util.c:1092 __mmap_region mm/mmap.c:1796 [inline] mmap_region+0xb00/0x13d4 mm/mmap.c:2933 do_mmap+0x6d0/0xe24 mm/mmap.c:1586 vm_mmap_pgoff+0x194/0x298 mm/util.c:551 ksys_mmap_pgoff+0x3c4/0x638 mm/mmap.c:1635 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline] __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline] __arm64_sys_mmap+0x108/0x120 arch/arm64/kernel/sys.c:21 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x28c arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x5c/0x140 arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #2 (&mm->mmap_lock){++++}-{3:3}: __might_fault+0xc8/0x128 mm/memory.c:5357 filldir64+0x2c0/0xa08 fs/readdir.c:335 dir_emit_dot include/linux/fs.h:3718 [inline] dir_emit_dots include/linux/fs.h:3729 [inline] dcache_readdir+0x144/0x668 fs/libfs.c:196 iterate_dir+0x1f0/0x4d0 fs/readdir.c:-1 __do_sys_getdents64 fs/readdir.c:369 [inline] __se_sys_getdents64 fs/readdir.c:354 [inline] __arm64_sys_getdents64+0x11c/0x338 fs/readdir.c:354 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x28c arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x5c/0x140 arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #1 (&type->i_mutex_dir_key#5){++++}-{3:3}: down_read+0xc0/0x38c kernel/locking/rwsem.c:1498 inode_lock_shared include/linux/fs.h:797 [inline] lookup_slow+0x50/0x84 fs/namei.c:1687 walk_component+0x2b8/0x3b8 fs/namei.c:1984 lookup_last fs/namei.c:2439 [inline] path_lookupat+0x168/0x3f0 fs/namei.c:2463 filename_lookup+0x1c8/0x478 fs/namei.c:2492 kern_path+0x4c/0x190 fs/namei.c:2590 lookup_bdev+0xc0/0x24c block/bdev.c:978 device_matched fs/btrfs/volumes.c:568 [inline] btrfs_free_stale_devices+0x614/0x950 fs/btrfs/volumes.c:608 btrfs_forget_devices+0x5c/0x98 fs/btrfs/volumes.c:1431 btrfs_control_ioctl+0x130/0x24c fs/btrfs/super.c:2450 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x28c arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x5c/0x140 arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1d0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #0 (&fs_devs->device_list_mutex){+.+.}-{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+0x28b0/0x65d4 kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x618 kernel/locking/lockdep.c:5623 __mutex_lock_common+0x1a4/0x1ea4 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 btrfs_run_dev_stats+0xe8/0xd2c fs/btrfs/volumes.c:7998 commit_cowonly_roots+0x14c/0x7e0 fs/btrfs/transaction.c:1293 btrfs_commit_transaction+0xf68/0x30ac fs/btrfs/transaction.c:2395 btrfs_sync_fs+0x240/0xb2c fs/btrfs/super.c:1454 sync_filesystem+0x1a0/0x218 fs/sync.c:66 generic_shutdown_super+0x74/0x2f8 fs/super.c:448 kill_anon_super+0x4c/0x80 fs/super.c:1089 btrfs_kill_super+0x44/0x5c fs/btrfs/super.c:2390 deactivate_locked_super+0xc0/0x13c fs/super.c:335 deactivate_super+0xf0/0x110 fs/super.c:366 cleanup_mnt+0x3bc/0x470 fs/namespace.c:1148 __cleanup_mnt+0x20/0x30 fs/namespace.c:1155 task_work_run+0x13c/0x1e8 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] do_notify_resume+0x2488/0x30a8 arch/arm64/kernel/signal.c:949 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xf0/0x1d0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 other info that might help us debug this: Chain exists of: &fs_devs->device_list_mutex --> &fs_info->reloc_mutex --> &fs_info->tree_log_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fs_info->tree_log_mutex); lock(&fs_info->reloc_mutex); lock(&fs_info->tree_log_mutex); lock(&fs_devs->device_list_mutex); *** DEADLOCK *** 3 locks held by syz-executor/4584: #0: ffff0000d5e000e0 (&type->s_umount_key#54){+.+.}-{3:3}, at: deactivate_super+0xe8/0x110 fs/super.c:365 #1: ffff0000d5a90c90 (&fs_info->reloc_mutex){+.+.}-{3:3}, at: btrfs_commit_transaction+0xe14/0x30ac fs/btrfs/transaction.c:2320 #2: ffff0000d5a90720 (&fs_info->tree_log_mutex){+.+.}-{3:3}, at: btrfs_commit_transaction+0xea8/0x30ac fs/btrfs/transaction.c:2370 stack backtrace: CPU: 1 PID: 4584 Comm: syz-executor Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026 Call trace: dump_backtrace+0x0/0x458 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2011 check_noncircular+0x264/0x2f8 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+0x28b0/0x65d4 kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x618 kernel/locking/lockdep.c:5623 __mutex_lock_common+0x1a4/0x1ea4 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743 btrfs_run_dev_stats+0xe8/0xd2c fs/btrfs/volumes.c:7998 commit_cowonly_roots+0x14c/0x7e0 fs/btrfs/transaction.c:1293 btrfs_commit_transaction+0xf68/0x30ac fs/btrfs/transaction.c:2395 btrfs_sync_fs+0x240/0xb2c fs/btrfs/super.c:1454 sync_filesystem+0x1a0/0x218 fs/sync.c:66 generic_shutdown_super+0x74/0x2f8 fs/super.c:448 kill_anon_super+0x4c/0x80 fs/super.c:1089 btrfs_kill_super+0x44/0x5c fs/btrfs/super.c:2390 deactivate_locked_super+0xc0/0x13c fs/super.c:335 deactivate_super+0xf0/0x110 fs/super.c:366 cleanup_mnt+0x3bc/0x470 fs/namespace.c:1148 __cleanup_mnt+0x20/0x30 fs/namespace.c:1155 task_work_run+0x13c/0x1e8 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] do_notify_resume+0x2488/0x30a8 arch/arm64/kernel/signal.c:949 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_svc+0xf0/0x1d0 arch/arm64/kernel/entry-common.c:609 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584