====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc3-syzkaller-00019-gbc3372351d0c #0 Not tainted ------------------------------------------------------ syz.3.999/2108 is trying to acquire lock: ffff888022ab15e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:193 but task is already holding lock: ffff88801bef5148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x274/0x870 fs/kernfs/dir.c:1890 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&root->kernfs_rwsem){++++}-{4:4}: lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 down_write+0x9c/0x220 kernel/locking/rwsem.c:1577 kernfs_add_one+0x41/0x530 fs/kernfs/dir.c:791 kernfs_create_dir_ns+0xd9/0x120 fs/kernfs/dir.c:1091 sysfs_create_dir_ns+0x1a2/0x3f0 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x435/0x8d0 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x126/0x190 lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x117/0x2f0 fs/btrfs/sysfs.c:2616 btrfs_quota_enable+0x287/0x21a0 fs/btrfs/qgroup.c:1030 btrfs_ioctl_quota_ctl+0x144/0x1c0 fs/btrfs/ioctl.c:3676 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x1a5/0x10c0 kernel/locking/mutex.c:746 btrfs_qgroup_inherit+0x1ee/0x2d90 fs/btrfs/qgroup.c:3355 create_subvol+0x705/0x1ac0 fs/btrfs/ioctl.c:572 btrfs_mksubvol+0x5c2/0x720 fs/btrfs/ioctl.c:938 __btrfs_ioctl_snap_create+0x19f/0x4b0 fs/btrfs/ioctl.c:1214 btrfs_ioctl_snap_create+0x12f/0x180 fs/btrfs/ioctl.c:1273 btrfs_ioctl+0xb4b/0xcf0 fs/btrfs/ioctl.c:-1 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 join_transaction+0x1aa/0xe60 fs/btrfs/transaction.c:321 start_transaction+0x770/0x16b0 fs/btrfs/transaction.c:705 btrfs_create_common+0x1b4/0x2e0 fs/btrfs/inode.c:6645 lookup_open fs/namei.c:3701 [inline] open_last_lookups fs/namei.c:3800 [inline] path_openat+0x194b/0x35d0 fs/namei.c:4036 do_filp_open+0x284/0x4e0 fs/namei.c:4066 do_sys_openat2+0x12b/0x1d0 fs/open.c:1429 do_sys_open fs/open.c:1444 [inline] __do_sys_open fs/open.c:1452 [inline] __se_sys_open fs/open.c:1448 [inline] __x64_sys_open+0x226/0x280 fs/open.c:1448 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (btrfs_trans_num_writers){++++}-{0:0}: reacquire_held_locks+0x12a/0x1e0 kernel/locking/lockdep.c:5383 __lock_release kernel/locking/lockdep.c:5572 [inline] lock_release+0x27a/0x3e0 kernel/locking/lockdep.c:5887 percpu_up_read include/linux/percpu-rwsem.h:100 [inline] __sb_end_write include/linux/fs.h:1778 [inline] sb_end_intwrite+0x26/0x1c0 include/linux/fs.h:1895 __btrfs_end_transaction+0x251/0x630 fs/btrfs/transaction.c:1075 btrfs_dirty_inode+0x151/0x1a0 fs/btrfs/inode.c:6140 inode_update_time fs/inode.c:2076 [inline] touch_atime+0x27d/0x690 fs/inode.c:2149 file_accessed include/linux/fs.h:2599 [inline] btrfs_file_mmap+0xbd/0x120 fs/btrfs/file.c:1938 call_mmap include/linux/fs.h:2243 [inline] mmap_file mm/internal.h:167 [inline] __mmap_new_file_vma mm/vma.c:2353 [inline] __mmap_new_vma mm/vma.c:2417 [inline] __mmap_region mm/vma.c:2519 [inline] mmap_region+0x241d/0x2ea0 mm/vma.c:2597 do_mmap+0xd42/0x1420 mm/mmap.c:561 vm_mmap_pgoff+0x2a2/0x530 mm/util.c:579 ksys_mmap_pgoff+0x4ee/0x720 mm/mmap.c:607 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&mm->mmap_lock){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xa69/0x24e0 kernel/locking/lockdep.c:3909 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 down_read_killable+0xcb/0xcb0 kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:193 get_mmap_lock_carefully mm/memory.c:6355 [inline] lock_mm_and_find_vma+0x29c/0x2f0 mm/memory.c:6406 do_user_addr_fault arch/x86/mm/fault.c:1360 [inline] handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x1c1/0x920 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 filldir+0x2c4/0x6a0 fs/readdir.c:291 dir_emit include/linux/fs.h:3861 [inline] kernfs_fop_readdir+0x545/0x870 fs/kernfs/dir.c:1907 iterate_dir+0x5a9/0x760 fs/readdir.c:108 __do_sys_getdents fs/readdir.c:322 [inline] __se_sys_getdents+0x1ff/0x4e0 fs/readdir.c:308 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x210 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: &mm->mmap_lock --> &fs_info->qgroup_ioctl_lock --> &root->kernfs_rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&root->kernfs_rwsem); lock(&fs_info->qgroup_ioctl_lock); lock(&root->kernfs_rwsem); rlock(&mm->mmap_lock); *** DEADLOCK *** 3 locks held by syz.3.999/2108: #0: ffff888033551cf8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x310 fs/file.c:1213 #1: ffff88807b8d6480 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x4a6/0x760 fs/readdir.c:101 #2: ffff88801bef5148 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x274/0x870 fs/kernfs/dir.c:1890 stack backtrace: CPU: 0 UID: 0 PID: 2108 Comm: syz.3.999 Not tainted 6.15.0-rc3-syzkaller-00019-gbc3372351d0c #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2079 check_noncircular+0x142/0x160 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xa69/0x24e0 kernel/locking/lockdep.c:3909 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 down_read_killable+0xcb/0xcb0 kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:193 get_mmap_lock_carefully mm/memory.c:6355 [inline] lock_mm_and_find_vma+0x29c/0x2f0 mm/memory.c:6406 do_user_addr_fault arch/x86/mm/fault.c:1360 [inline] handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x1c1/0x920 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0010:filldir+0x2c4/0x6a0 fs/readdir.c:292 Code: 87 55 02 00 00 0f 01 cb 0f ae e8 48 8b 44 24 30 49 89 46 08 48 8b 4c 24 10 48 8b 44 24 60 48 89 01 48 8b 44 24 18 8b 6c 24 3c <66> 89 41 10 48 98 40 88 6c 01 ff 48 89 44 24 30 4d 63 f5 42 c6 44 RSP: 0018:ffffc9000ce97c30 EFLAGS: 00050287 RAX: 0000000000000028 RBX: 0000200000002018 RCX: 0000200000001ff0 RDX: 0000000000000000 RSI: 0000200000001fd8 RDI: 0000200000002018 RBP: 0000000000000008 R08: ffffffff8241f82d R09: 1ffff110044f0000 R10: dffffc0000000000 R11: ffffed10044f0001 R12: ffff8880292d5c60 R13: 000000000000000d R14: 0000200000001fd8 R15: 00007ffffffff000 dir_emit include/linux/fs.h:3861 [inline] kernfs_fop_readdir+0x545/0x870 fs/kernfs/dir.c:1907 iterate_dir+0x5a9/0x760 fs/readdir.c:108 __do_sys_getdents fs/readdir.c:322 [inline] __se_sys_getdents+0x1ff/0x4e0 fs/readdir.c:308 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f374e78e169 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:00007f374f578038 EFLAGS: 00000246 ORIG_RAX: 000000000000004e RAX: ffffffffffffffda RBX: 00007f374e9b6080 RCX: 00007f374e78e169 RDX: 00000000000000b8 RSI: 0000200000001fc0 RDI: 0000000000000004 RBP: 00007f374e810a68 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f374e9b6080 R15: 00007ffe1dc5df98 ---------------- Code disassembly (best guess): 0: 87 55 02 xchg %edx,0x2(%rbp) 3: 00 00 add %al,(%rax) 5: 0f 01 cb stac 8: 0f ae e8 lfence b: 48 8b 44 24 30 mov 0x30(%rsp),%rax 10: 49 89 46 08 mov %rax,0x8(%r14) 14: 48 8b 4c 24 10 mov 0x10(%rsp),%rcx 19: 48 8b 44 24 60 mov 0x60(%rsp),%rax 1e: 48 89 01 mov %rax,(%rcx) 21: 48 8b 44 24 18 mov 0x18(%rsp),%rax 26: 8b 6c 24 3c mov 0x3c(%rsp),%ebp * 2a: 66 89 41 10 mov %ax,0x10(%rcx) <-- trapping instruction 2e: 48 98 cltq 30: 40 88 6c 01 ff mov %bpl,-0x1(%rcx,%rax,1) 35: 48 89 44 24 30 mov %rax,0x30(%rsp) 3a: 4d 63 f5 movslq %r13d,%r14 3d: 42 rex.X 3e: c6 .byte 0xc6 3f: 44 rex.R