======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.270/7905 is trying to acquire lock:
ffff88802a90a5f8 (sb_pagefaults#2){.+.+}-{0:0}, at: do_page_mkwrite+0x150/0x310 mm/memory.c:3589
but task is already holding lock:
ffff888019c4d238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x275/0x8d0 fs/kernfs/dir.c:1898
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:796
kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1098
sysfs_create_dir_ns+0x12f/0x2a0 fs/sysfs/dir.c:59
create_dir lib/kobject.c:73 [inline]
kobject_add_internal+0x631/0xd10 lib/kobject.c:240
kobject_add_varg lib/kobject.c:374 [inline]
kobject_init_and_add+0x12b/0x1a0 lib/kobject.c:457
btrfs_sysfs_add_qgroups+0x116/0x2e0 fs/btrfs/sysfs.c:2604
btrfs_quota_enable+0x282/0x2850 fs/btrfs/qgroup.c:1034
btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3540
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+0x14d/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+0x2c6/0x2850 fs/btrfs/qgroup.c:1063
btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3540
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+0x14d/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+0x6b9/0x1650 fs/btrfs/transaction.c:708
btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6443
file_update_time_flags+0x2d5/0x4b0 fs/inode.c:2426
btrfs_page_mkwrite+0x5df/0x1b10 fs/btrfs/file.c:1914
do_page_mkwrite+0x150/0x310 mm/memory.c:3589
wp_page_shared mm/memory.c:3990 [inline]
do_wp_page+0x203b/0x49d0 mm/memory.c:4209
handle_pte_fault mm/memory.c:6333 [inline]
__handle_mm_fault mm/memory.c:6455 [inline]
handle_mm_fault+0x9f5/0x13c0 mm/memory.c:6624
do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334
handle_page_fault arch/x86/mm/fault.c:1474 [inline]
exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
-> #1 (btrfs_trans_num_writers){++++}-{0:0}:
__lock_release kernel/locking/lockdep.c:5574 [inline]
lock_release+0x199/0x3d0 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:1085
btrfs_dirty_inode+0x14c/0x190 fs/btrfs/inode.c:6457
file_update_time_flags+0x2d5/0x4b0 fs/inode.c:2426
btrfs_page_mkwrite+0x5df/0x1b10 fs/btrfs/file.c:1914
do_page_mkwrite+0x150/0x310 mm/memory.c:3589
wp_page_shared mm/memory.c:3990 [inline]
do_wp_page+0x203b/0x49d0 mm/memory.c:4209
handle_pte_fault mm/memory.c:6333 [inline]
__handle_mm_fault mm/memory.c:6455 [inline]
handle_mm_fault+0x9f5/0x13c0 mm/memory.c:6624
do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334
handle_page_fault arch/x86/mm/fault.c:1474 [inline]
exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0xf0/0x2e0 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+0x329/0x1b10 fs/btrfs/file.c:1873
do_page_mkwrite+0x150/0x310 mm/memory.c:3589
wp_page_shared mm/memory.c:3990 [inline]
do_wp_page+0x203b/0x49d0 mm/memory.c:4209
handle_pte_fault mm/memory.c:6333 [inline]
__handle_mm_fault mm/memory.c:6455 [inline]
handle_mm_fault+0x9f5/0x13c0 mm/memory.c:6624
do_user_addr_fault+0x75b/0x1340 arch/x86/mm/fault.c:1385
handle_page_fault arch/x86/mm/fault.c:1474 [inline]
exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
filldir+0x2b5/0x690 fs/readdir.c:295
dir_emit include/linux/fs.h:3566 [inline]
kernfs_fop_readdir+0x57e/0x8d0 fs/kernfs/dir.c:1915
iterate_dir+0x3a5/0x580 fs/readdir.c:108
__do_sys_getdents fs/readdir.c:327 [inline]
__se_sys_getdents+0xf1/0x270 fs/readdir.c:312
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/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.5.270/7905:
#0: ffff888035eedd28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1261
#1: ffff88804090d978 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x29e/0x580 fs/readdir.c:101
#2: ffff888019c4d238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x275/0x8d0 fs/kernfs/dir.c:1898
#3: ffff888035cfd1b0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:611 [inline]
#3: ffff888035cfd1b0 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:441 [inline]
#3: ffff888035cfd1b0 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x36/0x340 mm/mmap_lock.c:501
stack backtrace:
CPU: 0 UID: 0 PID: 7905 Comm: syz.5.270 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_circular_bug+0x2e1/0x300 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0xf0/0x2e0 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+0x329/0x1b10 fs/btrfs/file.c:1873
do_page_mkwrite+0x150/0x310 mm/memory.c:3589
wp_page_shared mm/memory.c:3990 [inline]
do_wp_page+0x203b/0x49d0 mm/memory.c:4209
handle_pte_fault mm/memory.c:6333 [inline]
__handle_mm_fault mm/memory.c:6455 [inline]
handle_mm_fault+0x9f5/0x13c0 mm/memory.c:6624
do_user_addr_fault+0x75b/0x1340 arch/x86/mm/fault.c:1385
handle_page_fault arch/x86/mm/fault.c:1474 [inline]
exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0010:filldir+0x2b5/0x690 fs/readdir.c:296
Code: 87 73 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 1c <66> 89 41 10 80 e2 0f 41 89 c7 42 88 54 39 ff 49 63 ee c6 44 29 12
RSP: 0018:ffffc90005f6fc40 EFLAGS: 00050283
RAX: 0000000000000020 RBX: ffffc90005f6fe38 RCX: 0000200000001ff0
RDX: 0000000000000008 RSI: 0000200000001fd8 RDI: 0000200000002010
RBP: 00007ffffffff000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1004e5f001 R12: 0000200000001fd8
R13: ffff888019c6c5c0 R14: 000000000000000b R15: 0000200000002010
dir_emit include/linux/fs.h:3566 [inline]
kernfs_fop_readdir+0x57e/0x8d0 fs/kernfs/dir.c:1915
iterate_dir+0x3a5/0x580 fs/readdir.c:108
__do_sys_getdents fs/readdir.c:327 [inline]
__se_sys_getdents+0xf1/0x270 fs/readdir.c:312
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1855dcc799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f184bc05028 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007f1856046090 RCX: 00007f1855dcc799
RDX: 00000000000000b8 RSI: 0000200000001fc0 RDI: 0000000000000009
RBP: 00007f1855e62c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1856046128 R14: 00007f1856046090 R15: 00007ffd166a1708
</TASK>
----------------
Code disassembly (best guess):
0: 87 73 02 xchg %esi,0x2(%rbx)
3: 00 00 add %al,(%rax)
5: 0f 01 cb stac
8: 0f ae e8 lfence
b: 48 8b 44 24 50 mov 0x50(%rsp),%rax
10: 49 89 44 24 08 mov %rax,0x8(%r12)
15: 48 8b 4c 24 08 mov 0x8(%rsp),%rcx
1a: 48 8b 44 24 58 mov 0x58(%rsp),%rax
1f: 48 89 01 mov %rax,(%rcx)
22: 48 8b 04 24 mov (%rsp),%rax
26: 8b 54 24 1c mov 0x1c(%rsp),%edx
* 2a: 66 89 41 10 mov %ax,0x10(%rcx) <-- trapping instruction
2e: 80 e2 0f and $0xf,%dl
31: 41 89 c7 mov %eax,%r15d
34: 42 88 54 39 ff mov %dl,-0x1(%rcx,%r15,1)
39: 49 63 ee movslq %r14d,%rbp
3c: c6 .byte 0xc6
3d: 44 29 12 sub %r10d,(%rdx)