======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc1-syzkaller-00060-ga24588245776 #0 Not tainted
------------------------------------------------------
syz.1.191/7483 is trying to acquire lock:
ffff88806a269fe0 (&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:
-> #5 (&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+0xf3/0x230 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #4 (&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_quota_enable+0x2cb/0x21a0 fs/btrfs/qgroup.c:1059
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+0xf3/0x230 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #3 (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_rebuild_free_space_tree+0xb4/0x500 fs/btrfs/free-space-tree.c:1317
btrfs_start_pre_rw_mount+0xef1/0x1310 fs/btrfs/disk-io.c:3074
open_ctree+0x246c/0x2990 fs/btrfs/disk-io.c:3614
btrfs_fill_super fs/btrfs/super.c:972 [inline]
btrfs_get_tree_super fs/btrfs/super.c:1898 [inline]
btrfs_get_tree+0x131c/0x19e0 fs/btrfs/super.c:2093
vfs_get_tree+0x90/0x2b0 fs/super.c:1759
fc_mount+0x1b/0xb0 fs/namespace.c:1293
btrfs_get_tree_subvol fs/btrfs/super.c:2051 [inline]
btrfs_get_tree+0x68a/0x19e0 fs/btrfs/super.c:2094
vfs_get_tree+0x90/0x2b0 fs/super.c:1759
do_new_mount+0x2cf/0xb70 fs/namespace.c:3879
do_mount fs/namespace.c:4219 [inline]
__do_sys_mount fs/namespace.c:4430 [inline]
__se_sys_mount+0x38c/0x400 fs/namespace.c:4407
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (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]
__file_update_time fs/inode.c:2305 [inline]
file_update_time+0x314/0x450 fs/inode.c:2335
btrfs_page_mkwrite+0x666/0x16e0 fs/btrfs/file.c:1814
do_page_mkwrite+0x159/0x340 mm/memory.c:3287
do_shared_fault mm/memory.c:5594 [inline]
do_fault mm/memory.c:5656 [inline]
do_pte_missing mm/memory.c:4160 [inline]
handle_pte_fault+0x10c6/0x61c0 mm/memory.c:5997
__handle_mm_fault mm/memory.c:6140 [inline]
handle_mm_fault+0x1030/0x1aa0 mm/memory.c:6309
do_user_addr_fault arch/x86/mm/fault.c:1388 [inline]
handle_page_fault arch/x86/mm/fault.c:1480 [inline]
exc_page_fault+0x2bb/0x920 arch/x86/mm/fault.c:1538
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
-> #1 (sb_pagefaults#3){.+.+}-{0:0}:
lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
percpu_down_read include/linux/percpu-rwsem.h:52 [inline]
__sb_start_write include/linux/fs.h:1783 [inline]
sb_start_pagefault include/linux/fs.h:1948 [inline]
btrfs_page_mkwrite+0x3ea/0x16e0 fs/btrfs/file.c:1798
do_page_mkwrite+0x159/0x340 mm/memory.c:3287
do_shared_fault mm/memory.c:5594 [inline]
do_fault mm/memory.c:5656 [inline]
do_pte_missing mm/memory.c:4160 [inline]
handle_pte_fault+0x10c6/0x61c0 mm/memory.c:5997
__handle_mm_fault mm/memory.c:6140 [inline]
handle_mm_fault+0x1030/0x1aa0 mm/memory.c:6309
do_user_addr_fault arch/x86/mm/fault.c:1388 [inline]
handle_page_fault arch/x86/mm/fault.c:1480 [inline]
exc_page_fault+0x2bb/0x920 arch/x86/mm/fault.c:1538
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
-> #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
filldir64+0x2bb/0x690 fs/readdir.c:-1
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_getdents64 fs/readdir.c:403 [inline]
__se_sys_getdents64+0x1e4/0x4c0 fs/readdir.c:389
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf3/0x230 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.1.191/7483:
#0: ffff88804c9ff7b8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x310 fs/file.c:1213
#1: ffff888050392988 (&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: 1 UID: 0 PID: 7483 Comm: syz.1.191 Not tainted 6.15.0-rc1-syzkaller-00060-ga24588245776 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
<TASK>
__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:filldir64+0x2bb/0x690 fs/readdir.c:374
Code: e8 48 8b 44 24 58 49 89 46 08 48 8b 4c 24 18 48 8b 44 24 50 48 89 01 48 8b 44 24 20 8b 54 24 34 66 89 41 10 88 51 12 4d 63 f7 <42> c6 44 31 13 00 48 8d 69 13 bf 07 00 00 00 44 89 fe e8 6e b4 80
RSP: 0018:ffffc90004bafc38 EFLAGS: 00050283
RAX: 0000000000000030 RBX: 0000200000003008 RCX: 0000200000002fd8
RDX: 0000000000000008 RSI: 0000200000002fb8 RDI: 0000200000003008
RBP: 00007ffffffff000 R08: ffffffff8242a42a R09: 1ffff1100b26cb40
R10: dffffc0000000000 R11: ffffed100b26cb41 R12: ffff88802912bac0
R13: ffffc90004bafe50 R14: 0000000000000016 R15: 0000000000000016
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_getdents64 fs/readdir.c:403 [inline]
__se_sys_getdents64+0x1e4/0x4c0 fs/readdir.c:389
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f63a2d8d169
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:00007f63a3b38038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f63a2fa6080 RCX: 00007f63a2d8d169
RDX: 0000000000001002 RSI: 0000200000002f40 RDI: 0000000000000004
RBP: 00007f63a2e0e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f63a2fa6080 R15: 00007fff8a00fe88
</TASK>
----------------
Code disassembly (best guess):
0: e8 48 8b 44 24 call 0x24448b4d
5: 58 pop %rax
6: 49 89 46 08 mov %rax,0x8(%r14)
a: 48 8b 4c 24 18 mov 0x18(%rsp),%rcx
f: 48 8b 44 24 50 mov 0x50(%rsp),%rax
14: 48 89 01 mov %rax,(%rcx)
17: 48 8b 44 24 20 mov 0x20(%rsp),%rax
1c: 8b 54 24 34 mov 0x34(%rsp),%edx
20: 66 89 41 10 mov %ax,0x10(%rcx)
24: 88 51 12 mov %dl,0x12(%rcx)
27: 4d 63 f7 movslq %r15d,%r14
* 2a: 42 c6 44 31 13 00 movb $0x0,0x13(%rcx,%r14,1) <-- trapping instruction
30: 48 8d 69 13 lea 0x13(%rcx),%rbp
34: bf 07 00 00 00 mov $0x7,%edi
39: 44 89 fe mov %r15d,%esi
3c: e8 .byte 0xe8
3d: 6e outsb %ds:(%rsi),(%dx)
3e: b4 80 mov $0x80,%ah