======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.6.295/8707 is trying to acquire lock:
ffff888023e425f8 (sb_pagefaults#2){.+.+}-{0:0}, at: do_page_mkwrite+0x150/0x310 mm/memory.c:3528
but task is already holding lock:
ffff88813ff74238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x267/0x870 fs/kernfs/dir.c:1896
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (&root->kernfs_rwsem){++++}-{4:4}:
down_write+0x3a/0x50 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+0x6b1/0xcd0 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+0x25b/0x2900 fs/btrfs/qgroup.c:1002
btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3613
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/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
-> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
btrfs_quota_enable+0x29d/0x2900 fs/btrfs/qgroup.c:1031
btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3613
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/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
-> #2 (btrfs_trans_num_extwriters){++++}-{0:0}:
join_transaction+0x1a4/0xc90 fs/btrfs/transaction.c:323
start_transaction+0x6b7/0x15f0 fs/btrfs/transaction.c:707
btrfs_rebuild_free_space_tree+0xad/0x6c0 fs/btrfs/free-space-tree.c:1330
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
-> #1 (btrfs_trans_num_writers){++++}-{0:0}:
__lock_release kernel/locking/lockdep.c:5574 [inline]
lock_release+0x1ab/0x3b0 kernel/locking/lockdep.c:5889
percpu_up_read include/linux/percpu-rwsem.h:112 [inline]
__sb_end_write include/linux/fs/super.h:14 [inline]
sb_end_intwrite+0x26/0x1c0 include/linux/fs/super.h:101
__btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1083
btrfs_dirty_inode+0x14c/0x190 fs/btrfs/inode.c:6337
inode_update_time fs/inode.c:2167 [inline]
file_update_time_flags+0x38d/0x4f0 fs/inode.c:2395
btrfs_page_mkwrite+0x5dd/0x1a80 fs/btrfs/file.c:1916
do_page_mkwrite+0x150/0x310 mm/memory.c:3528
do_shared_fault mm/memory.c:5831 [inline]
do_fault mm/memory.c:5893 [inline]
do_pte_missing+0x78b/0x27a0 mm/memory.c:4401
handle_pte_fault mm/memory.c:6273 [inline]
__handle_mm_fault mm/memory.c:6411 [inline]
handle_mm_fault+0xcc1/0x1330 mm/memory.c:6580
do_user_addr_fault+0x764/0x1380 arch/x86/mm/fault.c:1387
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
-> #0 (sb_pagefaults#2){.+.+}-{0:0}:
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
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_pagefault include/linux/fs/super.h:159 [inline]
btrfs_page_mkwrite+0x32c/0x1a80 fs/btrfs/file.c:1875
do_page_mkwrite+0x150/0x310 mm/memory.c:3528
wp_page_shared mm/memory.c:3929 [inline]
do_wp_page+0x25e8/0x4970 mm/memory.c:4148
handle_pte_fault mm/memory.c:6289 [inline]
__handle_mm_fault mm/memory.c:6411 [inline]
handle_mm_fault+0x9f6/0x1330 mm/memory.c:6580
do_user_addr_fault+0x764/0x1380 arch/x86/mm/fault.c:1387
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
user_access_begin arch/x86/include/asm/uaccess.h:-1 [inline]
filldir64+0x29d/0x690 fs/readdir.c:373
dir_emit include/linux/fs.h:3527 [inline]
kernfs_fop_readdir+0x53a/0x870 fs/kernfs/dir.c:1913
iterate_dir+0x3a5/0x580 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
other info that might help us debug this:
Chain exists of:
sb_pagefaults#2 --> &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#2);
*** DEADLOCK ***
4 locks held by syz.6.295/8707:
#0: ffff88804cb9db28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x253/0x320 fs/file.c:1255
#1: ffff8880638ad3f8 (&type->i_mutex_dir_key#4){++++}-{4:4}, at: iterate_dir+0x29e/0x580 fs/readdir.c:101
#2: ffff88813ff74238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x267/0x870 fs/kernfs/dir.c:1896
#3: ffff8880315d36b0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:410 [inline]
#3: ffff8880315d36b0 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:390 [inline]
#3: ffff8880315d36b0 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x32/0x300 mm/mmap_lock.c:450
stack backtrace:
CPU: 1 UID: 0 PID: 8707 Comm: syz.6.295 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
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
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_pagefault include/linux/fs/super.h:159 [inline]
btrfs_page_mkwrite+0x32c/0x1a80 fs/btrfs/file.c:1875
do_page_mkwrite+0x150/0x310 mm/memory.c:3528
wp_page_shared mm/memory.c:3929 [inline]
do_wp_page+0x25e8/0x4970 mm/memory.c:4148
handle_pte_fault mm/memory.c:6289 [inline]
__handle_mm_fault mm/memory.c:6411 [inline]
handle_mm_fault+0x9f6/0x1330 mm/memory.c:6580
do_user_addr_fault+0x764/0x1380 arch/x86/mm/fault.c:1387
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
RIP: 0010:filldir64+0x29d/0x690 fs/readdir.c:377
Code: 8b ff 4c 89 ff 4c 89 e6 e8 20 53 8b ff 4d 39 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
RSP: 0018:ffffc900054afc58 EFLAGS: 00050287
RAX: 00000000158f045c RBX: ffffc900054afe38 RCX: ffff88802b1cbc80
RDX: 0000000000000002 RSI: 0000200000003340 RDI: 0000200000003360
RBP: 00007ffffffff000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff82351f40 R12: 0000200000003340
R13: ffffffff8bdc46a0 R14: 0000000000000007 R15: 0000200000003360
dir_emit include/linux/fs.h:3527 [inline]
kernfs_fop_readdir+0x53a/0x870 fs/kernfs/dir.c:1913
iterate_dir+0x3a5/0x580 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
RIP: 0033:0x7feacc7ff749
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:00007feacaa3d038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007feacca56090 RCX: 00007feacc7ff749
RDX: 0000000000000030 RSI: 0000200000003340 RDI: 0000000000000008
RBP: 00007feacc883f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007feacca56128 R14: 00007feacca56090 R15: 00007ffc891e7d78
</TASK>
----------------
Code disassembly (best guess):
0: 8b ff mov %edi,%edi
2: 4c 89 ff mov %r15,%rdi
5: 4c 89 e6 mov %r12,%rsi
8: e8 20 53 8b ff call 0xff8b532d
d: 4d 39 e7 cmp %r12,%r15
10: 0f 82 5b 02 00 00 jb 0x271
16: 49 39 ef cmp %rbp,%r15
19: 0f 87 52 02 00 00 ja 0x271
1f: 0f 01 cb stac
22: 0f ae e8 lfence
25: 48 8b 44 24 50 mov 0x50(%rsp),%rax
* 2a: 49 89 44 24 08 mov %rax,0x8(%r12) <-- trapping instruction
2f: 48 8b 4c 24 08 mov 0x8(%rsp),%rcx
34: 48 8b 44 24 58 mov 0x58(%rsp),%rax
39: 48 89 01 mov %rax,(%rcx)
3c: 48 8b 04 24 mov (%rsp),%rax