BTRFS info (device loop5): first mount of filesystem 395ef67a-297e-477c-816d-cd80a5b93e5d BTRFS info (device loop5): using sha256 (sha256-lib) checksum algorithm BTRFS info (device loop5): using free-space-tree ====================================================== WARNING: possible circular locking dependency detected 6.16.0-syzkaller-01056-gae388edd4a8f #0 Tainted: G W ------------------------------------------------------ syz.5.183/7296 is trying to acquire lock: ffff88803bf1d850 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:421 but task is already holding lock: ffff88801988e238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x267/0x870 fs/kernfs/dir.c:1893 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&root->kernfs_rwsem){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 down_write+0x3a/0x50 kernel/locking/rwsem.c:1577 kernfs_add_one+0x41/0x520 fs/kernfs/dir.c:791 kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1093 sysfs_create_dir_ns+0x123/0x280 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x5a5/0xb50 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:2641 btrfs_quota_enable+0x253/0x2600 fs/btrfs/qgroup.c:1022 btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3667 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __mutex_lock_common kernel/locking/rtmutex_api.c:517 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:529 btrfs_quota_enable+0x28e/0x2600 fs/btrfs/qgroup.c:1051 btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3667 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 join_transaction+0x1a4/0xca0 fs/btrfs/transaction.c:321 start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705 btrfs_rebuild_free_space_tree+0xad/0x760 fs/btrfs/free-space-tree.c:1339 btrfs_start_pre_rw_mount+0x128f/0x1bf0 fs/btrfs/disk-io.c:3075 open_ctree+0x293a/0x3a10 fs/btrfs/disk-io.c:3617 btrfs_fill_super fs/btrfs/super.c:977 [inline] btrfs_get_tree_super fs/btrfs/super.c:1937 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2074 [inline] btrfs_get_tree+0xf55/0x1820 fs/btrfs/super.c:2108 vfs_get_tree+0x92/0x2b0 fs/super.c:1815 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3805 do_mount fs/namespace.c:4133 [inline] __do_sys_mount fs/namespace.c:4344 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4321 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (btrfs_trans_num_writers){++++}-{0:0}: reacquire_held_locks+0x127/0x1d0 kernel/locking/lockdep.c:5388 __lock_release kernel/locking/lockdep.c:5577 [inline] lock_release+0x1b4/0x3e0 kernel/locking/lockdep.c:5892 percpu_up_read include/linux/percpu-rwsem.h:112 [inline] __sb_end_write include/linux/fs.h:1791 [inline] sb_end_intwrite+0x26/0x1c0 include/linux/fs.h:1908 __btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1076 btrfs_dirty_inode+0x108/0x190 fs/btrfs/inode.c:6223 inode_update_time fs/inode.c:2075 [inline] touch_atime+0x2f9/0x6d0 fs/inode.c:2148 file_accessed include/linux/fs.h:2661 [inline] btrfs_file_mmap_prepare+0xde/0x150 fs/btrfs/file.c:2050 vfs_mmap_prepare include/linux/fs.h:2292 [inline] call_mmap_prepare mm/vma.c:2572 [inline] __mmap_region mm/vma.c:2609 [inline] mmap_region+0xa96/0x1f30 mm/vma.c:2692 do_mmap+0xc23/0x10c0 mm/mmap.c:561 vm_mmap_pgoff+0x31e/0x4c0 mm/util.c:579 ksys_mmap_pgoff+0x4e9/0x720 mm/mmap.c:607 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 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:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 down_read_killable+0x9d/0x220 kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:421 get_mmap_lock_carefully mm/mmap_lock.c:197 [inline] lock_mm_and_find_vma+0x2a8/0x300 mm/mmap_lock.c:248 do_user_addr_fault+0x331/0x1390 arch/x86/mm/fault.c:1359 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 filldir64+0x2c7/0x690 fs/readdir.c:-1 dir_emit include/linux/fs.h:3951 [inline] kernfs_fop_readdir+0x537/0x870 fs/kernfs/dir.c:1910 iterate_dir+0x5b8/0x780 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/0x3b0 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.5.183/7296: #0: ffff88803b7a5d28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x253/0x320 fs/file.c:1232 #1: ffff88803a5cb918 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x4ab/0x780 fs/readdir.c:101 #2: ffff88801988e238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x267/0x870 fs/kernfs/dir.c:1893 stack backtrace: CPU: 0 UID: 0 PID: 7296 Comm: syz.5.183 Tainted: G W 6.16.0-syzkaller-01056-gae388edd4a8f #0 PREEMPT_{RT,(full)} Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2046 check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3911 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 down_read_killable+0x9d/0x220 kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:421 get_mmap_lock_carefully mm/mmap_lock.c:197 [inline] lock_mm_and_find_vma+0x2a8/0x300 mm/mmap_lock.c:248 do_user_addr_fault+0x331/0x1390 arch/x86/mm/fault.c:1359 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0010:filldir64+0x2c7/0x690 fs/readdir.c:379 Code: e8 48 8b 44 24 50 49 89 44 24 08 48 8b 4c 24 08 48 8b 44 24 58 48 89 01 48 8b 04 24 8b 54 24 14 49 bc 00 00 00 00 00 fc ff df <66> 89 41 10 80 e2 0f 88 51 12 49 63 ee c6 44 29 13 00 4c 8d 79 13 RSP: 0018:ffffc900059b7c50 EFLAGS: 00050287 RAX: 0000000000000020 RBX: ffffc900059b7e38 RCX: 0000200000000ff8 RDX: 0000000000000008 RSI: 0000200000000fd8 RDI: 0000200000001018 RBP: 00007ffffffff000 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: ffffed1006a023b9 R12: dffffc0000000000 R13: ffff8880278ad220 R14: 000000000000000c R15: 0000200000001018 dir_emit include/linux/fs.h:3951 [inline] kernfs_fop_readdir+0x537/0x870 fs/kernfs/dir.c:1910 iterate_dir+0x5b8/0x780 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/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8415d2e9a9 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:00007f8413b8e038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 00007f8415f55fa0 RCX: 00007f8415d2e9a9 RDX: 0000000000001000 RSI: 0000200000000f80 RDI: 0000000000000007 RBP: 00007f8415db0d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f8415f55fa0 R15: 00007ffcdc2d4f58 ---------------- Code disassembly (best guess): 0: e8 48 8b 44 24 call 0x24448b4d 5: 50 push %rax 6: 49 89 44 24 08 mov %rax,0x8(%r12) b: 48 8b 4c 24 08 mov 0x8(%rsp),%rcx 10: 48 8b 44 24 58 mov 0x58(%rsp),%rax 15: 48 89 01 mov %rax,(%rcx) 18: 48 8b 04 24 mov (%rsp),%rax 1c: 8b 54 24 14 mov 0x14(%rsp),%edx 20: 49 bc 00 00 00 00 00 movabs $0xdffffc0000000000,%r12 27: fc ff df * 2a: 66 89 41 10 mov %ax,0x10(%rcx) <-- trapping instruction 2e: 80 e2 0f and $0xf,%dl 31: 88 51 12 mov %dl,0x12(%rcx) 34: 49 63 ee movslq %r14d,%rbp 37: c6 44 29 13 00 movb $0x0,0x13(%rcx,%rbp,1) 3c: 4c 8d 79 13 lea 0x13(%rcx),%r15