====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc1-syzkaller-00004-gaef17cb3d3c4 #0 Not tainted ------------------------------------------------------ syz.7.683/12280 is trying to acquire lock: ffff8880549c8520 (sb_pagefaults#3){.+.+}-{0:0}, at: do_page_mkwrite+0x14a/0x310 mm/memory.c:3378 but task is already holding lock: ffff88801b2fd188 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x264/0x870 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+0x96/0x1f0 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+0x59f/0xb40 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:2635 btrfs_quota_enable+0x278/0x1d50 fs/btrfs/qgroup.c:1030 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 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/mutex.c:602 [inline] __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:747 btrfs_quota_enable+0x2be/0x1d50 fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 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+0x1a4/0xd70 fs/btrfs/transaction.c:321 start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705 btrfs_rebuild_free_space_tree+0xb1/0x4e0 fs/btrfs/free-space-tree.c:1333 btrfs_start_pre_rw_mount+0xd76/0x1180 fs/btrfs/disk-io.c:3077 open_ctree+0x2078/0x2800 fs/btrfs/disk-io.c:3617 btrfs_fill_super+0x19d/0x2e0 fs/btrfs/super.c:968 btrfs_get_tree_super fs/btrfs/super.c:1893 [inline] btrfs_get_tree+0x107c/0x1630 fs/btrfs/super.c:2088 vfs_get_tree+0x92/0x2b0 fs/super.c:1802 fc_mount+0x1c/0xb0 fs/namespace.c:1290 btrfs_get_tree_subvol fs/btrfs/super.c:2046 [inline] btrfs_get_tree+0x67d/0x1630 fs/btrfs/super.c:2089 vfs_get_tree+0x92/0x2b0 fs/super.c:1802 do_new_mount+0x24a/0xa40 fs/namespace.c:3885 do_mount fs/namespace.c:4222 [inline] __do_sys_mount fs/namespace.c:4433 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4410 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:1788 [inline] sb_end_intwrite+0x26/0x1c0 include/linux/fs.h:1905 __btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1076 btrfs_dirty_inode+0x14c/0x190 fs/btrfs/inode.c:6239 inode_update_time fs/inode.c:2076 [inline] __file_update_time fs/inode.c:2305 [inline] file_update_time+0x347/0x490 fs/inode.c:2335 btrfs_page_mkwrite+0x572/0x18b0 fs/btrfs/file.c:1870 do_page_mkwrite+0x14a/0x310 mm/memory.c:3378 do_shared_fault mm/memory.c:5686 [inline] do_fault mm/memory.c:5748 [inline] do_pte_missing mm/memory.c:4251 [inline] handle_pte_fault mm/memory.c:6089 [inline] __handle_mm_fault+0x1a60/0x5620 mm/memory.c:6232 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6401 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336 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 -> #0 (sb_pagefaults#3){.+.+}-{0:0}: 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 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.h:1793 [inline] sb_start_pagefault include/linux/fs.h:1958 [inline] btrfs_page_mkwrite+0x308/0x18b0 fs/btrfs/file.c:1852 do_page_mkwrite+0x14a/0x310 mm/memory.c:3378 wp_page_shared mm/memory.c:3779 [inline] do_wp_page+0x268d/0x5800 mm/memory.c:3998 handle_pte_fault mm/memory.c:6105 [inline] __handle_mm_fault+0x1144/0x5620 mm/memory.c:6232 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6401 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387 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+0x2b2/0x690 fs/readdir.c:-1 dir_emit include/linux/fs.h:3915 [inline] kernfs_fop_readdir+0x537/0x870 fs/kernfs/dir.c:1910 iterate_dir+0x5af/0x770 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: sb_pagefaults#3 --> &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(sb_pagefaults#3); *** DEADLOCK *** 4 locks held by syz.7.683/12280: #0: ffff8880250200f8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x320 fs/file.c:1213 #1: ffff888077013398 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x49f/0x770 fs/readdir.c:101 #2: ffff88801b2fd188 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x264/0x870 fs/kernfs/dir.c:1893 #3: ffff88804b652be0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:431 [inline] #3: ffff88804b652be0 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:188 [inline] #3: ffff88804b652be0 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x32/0x300 mm/mmap_lock.c:248 stack backtrace: CPU: 0 UID: 0 PID: 12280 Comm: syz.7.683 Not tainted 6.16.0-rc1-syzkaller-00004-gaef17cb3d3c4 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 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 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.h:1793 [inline] sb_start_pagefault include/linux/fs.h:1958 [inline] btrfs_page_mkwrite+0x308/0x18b0 fs/btrfs/file.c:1852 do_page_mkwrite+0x14a/0x310 mm/memory.c:3378 wp_page_shared mm/memory.c:3779 [inline] do_wp_page+0x268d/0x5800 mm/memory.c:3998 handle_pte_fault mm/memory.c:6105 [inline] __handle_mm_fault+0x1144/0x5620 mm/memory.c:6232 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6401 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387 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+0x2b2/0x690 fs/readdir.c:378 Code: e7 0f 82 5b 02 00 00 49 39 ef 0f 87 52 02 00 00 0f 01 cb 0f ae 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 RSP: 0018:ffffc90003477c50 EFLAGS: 00050283 RAX: 00000000000000ff RBX: ffffc90003477e38 RCX: 0000200000004000 RDX: 0000000000000002 RSI: 0000200000003fd8 RDI: 0000200000004020 RBP: 00007ffffffff000 R08: ffff88802b473c07 R09: 1ffff1100568e780 R10: dffffc0000000000 R11: ffffed100568e781 R12: 0000200000003fd8 R13: ffff888026a85e00 R14: 000000000000000b R15: 0000200000004020 dir_emit include/linux/fs.h:3915 [inline] kernfs_fop_readdir+0x537/0x870 fs/kernfs/dir.c:1910 iterate_dir+0x5af/0x770 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: 0033:0x7fddbd98e929 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:00007fddbe73a038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 00007fddbdbb5fa0 RCX: 00007fddbd98e929 RDX: 0000000000001010 RSI: 0000200000003fc0 RDI: 0000000000000003 RBP: 00007fddbda10b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fddbdbb5fa0 R15: 00007fff4fc3c068 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 0f 82 5b 02 00 00 jb 0x261 6: 49 39 ef cmp %rbp,%r15 9: 0f 87 52 02 00 00 ja 0x261 f: 0f 01 cb stac 12: 0f ae e8 lfence 15: 48 8b 44 24 50 mov 0x50(%rsp),%rax 1a: 49 89 44 24 08 mov %rax,0x8(%r12) 1f: 48 8b 4c 24 08 mov 0x8(%rsp),%rcx 24: 48 8b 44 24 58 mov 0x58(%rsp),%rax * 29: 48 89 01 mov %rax,(%rcx) <-- trapping instruction 2c: 48 8b 04 24 mov (%rsp),%rax 30: 8b 54 24 14 mov 0x14(%rsp),%edx 34: 49 bc 00 00 00 00 00 movabs $0xdffffc0000000000,%r12 3b: fc ff df 3e: 66 data16