====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.1.154/7589 is trying to acquire lock: ffff0000c1844188 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_add_one+0x48/0x574 fs/kernfs/dir.c:796 but task is already holding lock: ffff0000d5a81990 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}, at: btrfs_quota_enable+0x1cc/0x2438 fs/btrfs/qgroup.c:998 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:614 __mutex_lock kernel/locking/mutex.c:776 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:828 btrfs_create_qgroup+0x60/0x46c fs/btrfs/qgroup.c:1648 create_pending_snapshot+0x6c4/0x2d6c fs/btrfs/transaction.c:1748 create_pending_snapshots+0x150/0x198 fs/btrfs/transaction.c:1940 btrfs_commit_transaction+0x1018/0x2d30 fs/btrfs/transaction.c:2430 create_snapshot fs/btrfs/ioctl.c:779 [inline] btrfs_mksubvol+0x94c/0xea0 fs/btrfs/ioctl.c:926 btrfs_mksnapshot+0xb4/0x140 fs/btrfs/ioctl.c:968 __btrfs_ioctl_snap_create+0x404/0x5b8 fs/btrfs/ioctl.c:1232 btrfs_ioctl_snap_create_v2+0x1b4/0x308 fs/btrfs/ioctl.c:1312 btrfs_ioctl+0xa5c/0xc3c fs/btrfs/ioctl.c:-1 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #4 (&fs_info->reloc_mutex){+.+.}-{4:4}: __mutex_lock_common+0x1d0/0x2678 kernel/locking/mutex.c:614 __mutex_lock kernel/locking/mutex.c:776 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:828 btrfs_record_root_in_trans fs/btrfs/transaction.c:505 [inline] start_transaction+0x480/0x1530 fs/btrfs/transaction.c:781 btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:832 btrfs_dirty_inode+0x90/0x190 fs/btrfs/inode.c:6324 btrfs_update_time+0xa0/0xd0 fs/btrfs/inode.c:6358 inode_update_time fs/inode.c:2167 [inline] touch_atime+0x2e4/0x818 fs/inode.c:2240 file_accessed include/linux/fs.h:2254 [inline] btrfs_file_mmap_prepare+0x148/0x1c4 fs/btrfs/file.c:2053 vfs_mmap_prepare include/linux/fs.h:2058 [inline] call_mmap_prepare mm/vma.c:2596 [inline] __mmap_region mm/vma.c:2692 [inline] mmap_region+0x910/0x1978 mm/vma.c:2786 do_mmap+0x968/0xfac mm/mmap.c:558 vm_mmap_pgoff+0x2d8/0x45c mm/util.c:581 ksys_mmap_pgoff+0x394/0x5b8 mm/mmap.c:604 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline] __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline] __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #3 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x190/0xb5c fs/btrfs/transaction.c:323 start_transaction+0x778/0x1530 fs/btrfs/transaction.c:707 btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:832 btrfs_dirty_inode+0x90/0x190 fs/btrfs/inode.c:6324 btrfs_update_time+0xa0/0xd0 fs/btrfs/inode.c:6358 inode_update_time fs/inode.c:2167 [inline] touch_atime+0x2e4/0x818 fs/inode.c:2240 file_accessed include/linux/fs.h:2254 [inline] btrfs_file_mmap_prepare+0x148/0x1c4 fs/btrfs/file.c:2053 vfs_mmap_prepare include/linux/fs.h:2058 [inline] call_mmap_prepare mm/vma.c:2596 [inline] __mmap_region mm/vma.c:2692 [inline] mmap_region+0x910/0x1978 mm/vma.c:2786 do_mmap+0x968/0xfac mm/mmap.c:558 vm_mmap_pgoff+0x2d8/0x45c mm/util.c:581 ksys_mmap_pgoff+0x394/0x5b8 mm/mmap.c:604 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline] __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline] __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #2 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5574 [inline] lock_release+0x18c/0x39c kernel/locking/lockdep.c:5889 percpu_up_read include/linux/percpu-rwsem.h:112 [inline] __sb_end_write include/linux/fs/super.h:14 [inline] sb_end_intwrite+0x3c/0x348 include/linux/fs/super.h:101 __btrfs_end_transaction+0x1f4/0x5f4 fs/btrfs/transaction.c:1083 btrfs_end_transaction+0x24/0x34 fs/btrfs/transaction.c:1117 btrfs_dirty_inode+0x140/0x190 fs/btrfs/inode.c:6338 btrfs_update_time+0xa0/0xd0 fs/btrfs/inode.c:6358 inode_update_time fs/inode.c:2167 [inline] touch_atime+0x2e4/0x818 fs/inode.c:2240 file_accessed include/linux/fs.h:2254 [inline] btrfs_file_mmap_prepare+0x148/0x1c4 fs/btrfs/file.c:2053 vfs_mmap_prepare include/linux/fs.h:2058 [inline] call_mmap_prepare mm/vma.c:2596 [inline] __mmap_region mm/vma.c:2692 [inline] mmap_region+0x910/0x1978 mm/vma.c:2786 do_mmap+0x968/0xfac mm/mmap.c:558 vm_mmap_pgoff+0x2d8/0x45c mm/util.c:581 ksys_mmap_pgoff+0x394/0x5b8 mm/mmap.c:604 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline] __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline] __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #1 (&mm->mmap_lock){++++}-{4:4}: down_read_killable+0x60/0x344 kernel/locking/rwsem.c:1560 mmap_read_lock_killable+0x28/0x8c include/linux/mmap_lock.h:400 get_mmap_lock_carefully mm/mmap_lock.c:399 [inline] lock_mm_and_find_vma+0x2a4/0x2d8 mm/mmap_lock.c:450 do_page_fault+0x50c/0x13cc arch/arm64/mm/fault.c:678 do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:793 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:933 el1_abort+0x40/0x64 arch/arm64/kernel/entry-common.c:303 el1h_64_sync_handler+0x50/0xfc arch/arm64/kernel/entry-common.c:437 el1h_64_sync+0x6c/0x70 arch/arm64/kernel/entry.S:591 __uaccess_mask_ptr arch/arm64/include/asm/uaccess.h:169 [inline] filldir64+0x2ec/0x6bc fs/readdir.c:379 dir_emit include/linux/fs.h:3527 [inline] kernfs_fop_readdir+0x498/0x79c fs/kernfs/dir.c:1915 iterate_dir+0x2dc/0x478 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64 fs/readdir.c:396 [inline] __arm64_sys_getdents64+0x110/0x2fc fs/readdir.c:396 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #0 (&root->kernfs_rwsem){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x2e0 kernel/locking/lockdep.c:5868 down_write+0x50/0xc0 kernel/locking/rwsem.c:1590 kernfs_add_one+0x48/0x574 fs/kernfs/dir.c:796 kernfs_create_dir_ns+0xd4/0x12c fs/kernfs/dir.c:1098 sysfs_create_dir_ns+0x114/0x24c fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x5a8/0xb48 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x118/0x17c lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x110/0x268 fs/btrfs/sysfs.c:2697 btrfs_quota_enable+0x210/0x2438 fs/btrfs/qgroup.c:1002 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3613 btrfs_ioctl+0x86c/0xc3c fs/btrfs/ioctl.c:5296 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 other info that might help us debug this: Chain exists of: &root->kernfs_rwsem --> &fs_info->reloc_mutex --> &fs_info->qgroup_ioctl_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fs_info->qgroup_ioctl_lock); lock(&fs_info->reloc_mutex); lock(&fs_info->qgroup_ioctl_lock); lock(&root->kernfs_rwsem); *** DEADLOCK *** 3 locks held by syz.1.154/7589: #0: ffff0000d7aaa420 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:543 #1: ffff0000d5a80c60 (&fs_info->subvol_sem){++++}-{4:4}, at: btrfs_ioctl_quota_ctl+0x16c/0x1bc fs/btrfs/ioctl.c:3612 #2: ffff0000d5a81990 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}, at: btrfs_quota_enable+0x1cc/0x2438 fs/btrfs/qgroup.c:998 stack backtrace: CPU: 0 UID: 0 PID: 7589 Comm: syz.1.154 Tainted: G L syzkaller #0 PREEMPT Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2043 check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x2e0 kernel/locking/lockdep.c:5868 down_write+0x50/0xc0 kernel/locking/rwsem.c:1590 kernfs_add_one+0x48/0x574 fs/kernfs/dir.c:796 kernfs_create_dir_ns+0xd4/0x12c fs/kernfs/dir.c:1098 sysfs_create_dir_ns+0x114/0x24c fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x5a8/0xb48 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x118/0x17c lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x110/0x268 fs/btrfs/sysfs.c:2697 btrfs_quota_enable+0x210/0x2438 fs/btrfs/qgroup.c:1002 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3613 btrfs_ioctl+0x86c/0xc3c fs/btrfs/ioctl.c:5296 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:583 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x5c/0x26c arch/arm64/kernel/entry-common.c:724 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596