BTRFS info (device loop5): max_inline set to 0 ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.5.5955/600 is trying to acquire lock: ffff88801cab0188 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_add_one+0x41/0x5c0 fs/kernfs/dir.c:794 but task is already holding lock: ffff8880898b1990 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}, at: btrfs_quota_enable+0x214/0x28f0 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 kernel/locking/mutex.c:614 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:776 btrfs_create_qgroup+0x55/0x520 fs/btrfs/qgroup.c:1648 create_pending_snapshot+0x86c/0x3230 fs/btrfs/transaction.c:1748 create_pending_snapshots+0x17c/0x1c0 fs/btrfs/transaction.c:1940 btrfs_commit_transaction+0xf78/0x3b10 fs/btrfs/transaction.c:2430 create_snapshot fs/btrfs/ioctl.c:779 [inline] btrfs_mksubvol+0xc75/0x12c0 fs/btrfs/ioctl.c:926 btrfs_mksnapshot+0xab/0xf0 fs/btrfs/ioctl.c:968 __btrfs_ioctl_snap_create+0x520/0x730 fs/btrfs/ioctl.c:1232 btrfs_ioctl_snap_create_v2+0x1f8/0x3b0 fs/btrfs/ioctl.c:1312 btrfs_ioctl+0xa62/0xd00 fs/btrfs/ioctl.c:-1 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&fs_info->reloc_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:776 btrfs_commit_transaction+0xf6b/0x3b10 fs/btrfs/transaction.c:2423 btrfs_rebuild_free_space_tree+0x28b/0x6c0 fs/btrfs/free-space-tree.c:1375 btrfs_start_pre_rw_mount+0x128f/0x1bf0 fs/btrfs/disk-io.c:3052 open_ctree+0x2b11/0x3d20 fs/btrfs/disk-io.c:3603 btrfs_fill_super fs/btrfs/super.c:983 [inline] btrfs_get_tree_super fs/btrfs/super.c:1946 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2089 [inline] btrfs_get_tree+0x1061/0x1920 fs/btrfs/super.c:2123 vfs_get_tree+0x92/0x2a0 fs/super.c:1751 fc_mount fs/namespace.c:1199 [inline] do_new_mount_fc fs/namespace.c:3636 [inline] do_new_mount+0x302/0xa10 fs/namespace.c:3712 do_mount fs/namespace.c:4035 [inline] __do_sys_mount fs/namespace.c:4224 [inline] __se_sys_mount+0x313/0x410 fs/namespace.c:4201 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (btrfs_trans_unblocked){++++}-{0:0}: wait_current_trans+0x22b/0x520 fs/btrfs/transaction.c:533 start_transaction+0x6d2/0x15f0 fs/btrfs/transaction.c:709 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6324 inode_update_time fs/inode.c:2167 [inline] touch_atime+0x2f9/0x6d0 fs/inode.c:2240 file_accessed include/linux/fs.h:2254 [inline] iterate_dir+0x438/0x570 fs/readdir.c:111 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64+0xe4/0x260 fs/readdir.c:396 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (sb_internal#2){.+.+}-{0:0}: percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_intwrite include/linux/fs/super.h:177 [inline] start_transaction+0x56f/0x15f0 fs/btrfs/transaction.c:701 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6324 inode_update_time fs/inode.c:2167 [inline] touch_atime+0x2f9/0x6d0 fs/inode.c:2240 file_accessed include/linux/fs.h:2254 [inline] btrfs_file_mmap_prepare+0x176/0x1f0 fs/btrfs/file.c:2052 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+0xb2b/0x1d10 mm/vma.c:2786 do_mmap+0xc45/0x10d0 mm/mmap.c:558 vm_mmap_pgoff+0x2a6/0x4d0 mm/util.c:581 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:604 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&mm->mmap_lock){++++}-{4:4}: down_read_killable+0x50/0x350 kernel/locking/rwsem.c:1560 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:400 get_mmap_lock_carefully mm/mmap_lock.c:399 [inline] lock_mm_and_find_vma+0x2a8/0x300 mm/mmap_lock.c:450 do_user_addr_fault+0x331/0x1380 arch/x86/mm/fault.c:1359 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 filldir64+0x2ce/0x690 fs/readdir.c:-1 dir_emit include/linux/fs.h:3527 [inline] kernfs_fop_readdir+0x537/0x870 fs/kernfs/dir.c:1913 iterate_dir+0x399/0x570 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64+0xe4/0x260 fs/readdir.c:396 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #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+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590 kernfs_add_one+0x41/0x5c0 fs/kernfs/dir.c:794 kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1096 sysfs_create_dir_ns+0x123/0x280 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x6ab/0xcc0 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x125/0x190 lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x111/0x2b0 fs/btrfs/sysfs.c:2697 btrfs_quota_enable+0x25d/0x28f0 fs/btrfs/qgroup.c:1002 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3613 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f 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.5.5955/600: #0: ffff888060002420 (sb_writers#19){.+.+}-{0:0}, at: mnt_want_write_file+0x60/0x200 fs/namespace.c:543 #1: ffff8880898b0c60 (&fs_info->subvol_sem){++++}-{4:4}, at: btrfs_ioctl_quota_ctl+0x178/0x1c0 fs/btrfs/ioctl.c:3612 #2: ffff8880898b1990 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}, at: btrfs_quota_enable+0x214/0x28f0 fs/btrfs/qgroup.c:998 stack backtrace: CPU: 0 UID: 0 PID: 600 Comm: syz.5.5955 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 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+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590 kernfs_add_one+0x41/0x5c0 fs/kernfs/dir.c:794 kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1096 sysfs_create_dir_ns+0x123/0x280 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x6ab/0xcc0 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x125/0x190 lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x111/0x2b0 fs/btrfs/sysfs.c:2697 btrfs_quota_enable+0x25d/0x28f0 fs/btrfs/qgroup.c:1002 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3613 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6eb898f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f6eb9794038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f6eb8be5fa0 RCX: 00007f6eb898f749 RDX: 0000200000000580 RSI: 00000000c0109428 RDI: 0000000000000003 RBP: 00007f6eb8a13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6eb8be6038 R14: 00007f6eb8be5fa0 R15: 00007fff753a9c48