BTRFS info (device loop1): clearing compat-ro feature flag for FREE_SPACE_TREE (0x1) BTRFS info (device loop1): clearing compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2) ====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc7-syzkaller-g82af5ea7c611 #0 Not tainted ------------------------------------------------------ syz.1.215/8024 is trying to acquire lock: ffff000101649988 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}, at: btrfs_quota_enable+0x270/0x1c70 fs/btrfs/qgroup.c:1059 but task is already holding lock: ffff00010164a530 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x164/0xb5c fs/btrfs/transaction.c:320 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x190/0xb5c fs/btrfs/transaction.c:321 start_transaction+0x778/0x155c fs/btrfs/transaction.c:705 btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:830 btrfs_dirty_inode+0x90/0x190 fs/btrfs/inode.c:6225 btrfs_update_time+0xa0/0xd0 fs/btrfs/inode.c:6259 inode_update_time fs/inode.c:2076 [inline] touch_atime+0x2e4/0x818 fs/inode.c:2149 file_accessed include/linux/fs.h:2652 [inline] btrfs_file_mmap+0xac/0x118 fs/btrfs/file.c:1988 call_mmap include/linux/fs.h:2286 [inline] mmap_file mm/internal.h:167 [inline] __mmap_new_file_vma mm/vma.c:2405 [inline] __mmap_new_vma mm/vma.c:2467 [inline] __mmap_region mm/vma.c:2622 [inline] mmap_region+0xe9c/0x1c0c mm/vma.c:2692 do_mmap+0x968/0xfac mm/mmap.c:561 vm_mmap_pgoff+0x2b8/0x43c mm/util.c:579 ksys_mmap_pgoff+0x394/0x5b8 mm/mmap.c:607 __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+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #3 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5577 [inline] lock_release+0x198/0x39c kernel/locking/lockdep.c:5892 percpu_up_read include/linux/percpu-rwsem.h:112 [inline] __sb_end_write include/linux/fs.h:1790 [inline] sb_end_intwrite+0x3c/0x348 include/linux/fs.h:1907 __btrfs_end_transaction+0x1f4/0x5f4 fs/btrfs/transaction.c:1076 btrfs_end_transaction+0x24/0x34 fs/btrfs/transaction.c:1110 btrfs_dirty_inode+0x140/0x190 fs/btrfs/inode.c:6239 btrfs_update_time+0xa0/0xd0 fs/btrfs/inode.c:6259 inode_update_time fs/inode.c:2076 [inline] touch_atime+0x2e4/0x818 fs/inode.c:2149 file_accessed include/linux/fs.h:2652 [inline] btrfs_file_mmap+0xac/0x118 fs/btrfs/file.c:1988 call_mmap include/linux/fs.h:2286 [inline] mmap_file mm/internal.h:167 [inline] __mmap_new_file_vma mm/vma.c:2405 [inline] __mmap_new_vma mm/vma.c:2467 [inline] __mmap_region mm/vma.c:2622 [inline] mmap_region+0xe9c/0x1c0c mm/vma.c:2692 do_mmap+0x968/0xfac mm/mmap.c:561 vm_mmap_pgoff+0x2b8/0x43c mm/util.c:579 ksys_mmap_pgoff+0x394/0x5b8 mm/mmap.c:607 __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+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #2 (&mm->mmap_lock){++++}-{4:4}: down_read_killable+0x60/0x32c kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x28/0x8c include/linux/mmap_lock.h:421 get_mmap_lock_carefully mm/mmap_lock.c:197 [inline] lock_mm_and_find_vma+0x2a4/0x2d8 mm/mmap_lock.c:248 do_page_fault+0x50c/0x13cc arch/arm64/mm/fault.c:674 do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:789 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:929 el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:481 el1h_64_sync_handler+0x50/0xfc arch/arm64/kernel/entry-common.c:597 el1h_64_sync+0x6c/0x70 arch/arm64/kernel/entry.S:591 __uaccess_mask_ptr arch/arm64/include/asm/uaccess.h:169 [inline] filldir64+0x314/0x6bc fs/readdir.c:381 dir_emit include/linux/fs.h:3921 [inline] kernfs_fop_readdir+0x498/0x79c fs/kernfs/dir.c:1910 iterate_dir+0x458/0x5e0 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+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #1 (&root->kernfs_rwsem){++++}-{4:4}: down_write+0x50/0xc0 kernel/locking/rwsem.c:1577 kernfs_add_one+0x48/0x60c fs/kernfs/dir.c:791 kernfs_create_dir_ns+0xd4/0x12c fs/kernfs/dir.c:1093 sysfs_create_dir_ns+0x114/0x24c fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x5a8/0xb20 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:2635 btrfs_quota_enable+0x224/0x1c70 fs/btrfs/qgroup.c:1030 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3673 btrfs_ioctl+0x86c/0xc3c fs/btrfs/ioctl.c:5323 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:893 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 -> #0 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5240 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5871 __mutex_lock_common+0x1d0/0x2190 kernel/locking/mutex.c:602 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:799 btrfs_quota_enable+0x270/0x1c70 fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3673 btrfs_ioctl+0x86c/0xc3c fs/btrfs/ioctl.c:5323 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:893 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596 other info that might help us debug this: Chain exists of: &fs_info->qgroup_ioctl_lock --> btrfs_trans_num_writers --> btrfs_trans_num_extwriters Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(btrfs_trans_num_extwriters); lock(btrfs_trans_num_writers); lock(btrfs_trans_num_extwriters); lock(&fs_info->qgroup_ioctl_lock); *** DEADLOCK *** 5 locks held by syz.1.215/8024: #0: ffff0000fe2e6428 (sb_writers#29){.+.+}-{0:0}, at: mnt_want_write_file+0x64/0x1e8 fs/namespace.c:601 #1: ffff000101648c40 (&fs_info->subvol_sem){+.+.}-{4:4}, at: btrfs_ioctl_quota_ctl+0x16c/0x1bc fs/btrfs/ioctl.c:3672 #2: ffff0000fe2e6618 (sb_internal#5){.+.+}-{0:0}, at: btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:816 #3: ffff00010164a508 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0x134/0xb5c fs/btrfs/transaction.c:317 #4: ffff00010164a530 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x164/0xb5c fs/btrfs/transaction.c:320 stack backtrace: CPU: 1 UID: 0 PID: 8024 Comm: syz.1.215 Not tainted 6.16.0-rc7-syzkaller-g82af5ea7c611 #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/18/2025 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:2046 check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain kernel/locking/lockdep.c:3911 [inline] __lock_acquire+0x1774/0x30a4 kernel/locking/lockdep.c:5240 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5871 __mutex_lock_common+0x1d0/0x2190 kernel/locking/mutex.c:602 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:799 btrfs_quota_enable+0x270/0x1c70 fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3673 btrfs_ioctl+0x86c/0xc3c fs/btrfs/ioctl.c:5323 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:893 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596