option from the mount to silence this warning.
=======================================================
hfs: unable to locate alternate MDB
hfs: continuing without an alternate MDB
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/6066 is trying to acquire lock:
ffff888028b5a0a0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1
but task is already holding lock:
ffff888028b5a0a0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&tree->tree_lock/1);
lock(&tree->tree_lock/1);
*** DEADLOCK ***
May be due to missing lock nesting notation
5 locks held by syz.0.17/6066:
#0: ffff888028b58480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff888025dc18c0 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock_killable include/linux/fs.h:1032 [inline]
#1: ffff888025dc18c0 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: do_truncate+0x18f/0x250 fs/open.c:63
#2: ffff888025dc16e8 (&HFS_I(inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf2/0x15e0 fs/hfs/extent.c:397
#3: ffff888028b5a0a0 (&tree->tree_lock/1){+.+.}-{4:4}, at: hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1
#4: ffff888025dc0128 (&HFS_I(tree->inode)->extents_lock){+.+.}-{4:4}, at: hfs_extend_file+0xf2/0x15e0 fs/hfs/extent.c:397
stack backtrace:
CPU: 0 UID: 0 PID: 6066 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
check_deadlock kernel/locking/lockdep.c:3093 [inline]
validate_chain kernel/locking/lockdep.c:3895 [inline]
__lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
__mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552
hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1
hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
hfs_extend_file+0x35c/0x15e0 fs/hfs/extent.c:401
hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
__hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
__hfs_ext_cache_extent+0x6b/0x9b0 fs/hfs/extent.c:174
hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
hfs_extend_file+0x39b/0x15e0 fs/hfs/extent.c:401
hfs_get_block+0x412/0xc50 fs/hfs/extent.c:353
__block_write_begin_int+0x6c6/0x1910 fs/buffer.c:2145
block_write_begin fs/buffer.c:2256 [inline]
cont_write_begin+0x737/0xae0 fs/buffer.c:2594
hfs_write_begin+0x66/0xb0 fs/hfs/inode.c:53
cont_expand_zero fs/buffer.c:2522 [inline]
cont_write_begin+0x2e7/0xae0 fs/buffer.c:2584
hfs_write_begin+0x66/0xb0 fs/hfs/inode.c:53
hfs_file_truncate+0x1cf/0xb70 fs/hfs/extent.c:495
hfs_inode_setattr+0x4a9/0x670 fs/hfs/inode.c:666
notify_change+0xc18/0xf60 fs/attr.c:546
do_truncate+0x1c2/0x250 fs/open.c:68
vfs_truncate+0x4b4/0x540 fs/open.c:118
do_sys_truncate+0xf1/0x1c0 fs/open.c:141
__do_sys_truncate fs/open.c:153 [inline]
__se_sys_truncate fs/open.c:151 [inline]
__x64_sys_truncate+0x5b/0x70 fs/open.c:151
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fccb138acb9
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:00007ffe1470ca38 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007fccb1605fa0 RCX: 00007fccb138acb9
RDX: 0000000000000000 RSI: 0000000001001bfc RDI: 0000200000000040
RBP: 00007fccb13f8bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fccb1605fac R14: 00007fccb1605fa0 R15: 00007fccb1605fa0
------------[ cut here ]------------
rtmutex deadlock detected
WARNING: kernel/locking/rtmutex.c:1674 at rt_mutex_handle_deadlock+0x21/0xb0 kernel/locking/rtmutex.c:1674, CPU#0: syz.0.17/6066
Modules linked in:
CPU: 0 UID: 0 PID: 6066 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:rt_mutex_handle_deadlock+0x21/0xb0 kernel/locking/rtmutex.c:1674
Code: 90 90 90 90 90 90 90 90 90 41 57 41 56 41 55 41 54 53 83 ff dd 0f 85 81 00 00 00 48 89 f7 e8 96 39 01 00 48 8d 3d 5f 8c 2f 04 <67> 48 0f b9 3a 4c 8d 3d 00 00 00 00 65 48 8b 1d c3 69 05 07 4c 8d
RSP: 0018:ffffc90003c16c30 EFLAGS: 00010286
RAX: 0000000080000000 RBX: ffffc90003c16cc0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8b5f6240 RDI: ffffffff8f1e9290
RBP: ffffc90003c16dc8 R08: ffffffff8f1b6f77 R09: 1ffffffff1e36dee
R10: dffffc0000000000 R11: fffffbfff1e36def R12: 1ffff92000782d94
R13: ffffffff8aef00ed R14: ffff888028b5a048 R15: dffffc0000000000
FS: 000055558bf25500(0000) GS:ffff8881268d9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d588562138 CR3: 0000000040f94000 CR4: 00000000003526f0
Call Trace:
__rt_mutex_slowlock kernel/locking/rtmutex.c:1734 [inline]
__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
rt_mutex_slowlock+0x6c0/0x710 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
__mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline]
mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:552
hfs_find_init+0x18e/0x300 fs/hfs/bfind.c:-1
hfs_ext_read_extent fs/hfs/extent.c:200 [inline]
hfs_extend_file+0x35c/0x15e0 fs/hfs/extent.c:401
hfs_bmap_reserve+0x107/0x430 fs/hfs/btree.c:269
__hfs_ext_write_extent+0x1fa/0x470 fs/hfs/extent.c:121
__hfs_ext_cache_extent+0x6b/0x9b0 fs/hfs/extent.c:174
hfs_ext_read_extent fs/hfs/extent.c:202 [inline]
hfs_extend_file+0x39b/0x15e0 fs/hfs/extent.c:401
hfs_get_block+0x412/0xc50 fs/hfs/extent.c:353
__block_write_begin_int+0x6c6/0x1910 fs/buffer.c:2145
block_write_begin fs/buffer.c:2256 [inline]
cont_write_begin+0x737/0xae0 fs/buffer.c:2594
hfs_write_begin+0x66/0xb0 fs/hfs/inode.c:53
cont_expand_zero fs/buffer.c:2522 [inline]
cont_write_begin+0x2e7/0xae0 fs/buffer.c:2584
hfs_write_begin+0x66/0xb0 fs/hfs/inode.c:53
hfs_file_truncate+0x1cf/0xb70 fs/hfs/extent.c:495
hfs_inode_setattr+0x4a9/0x670 fs/hfs/inode.c:666
notify_change+0xc18/0xf60 fs/attr.c:546
do_truncate+0x1c2/0x250 fs/open.c:68
vfs_truncate+0x4b4/0x540 fs/open.c:118
do_sys_truncate+0xf1/0x1c0 fs/open.c:141
__do_sys_truncate fs/open.c:153 [inline]
__se_sys_truncate fs/open.c:151 [inline]
__x64_sys_truncate+0x5b/0x70 fs/open.c:151
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fccb138acb9
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:00007ffe1470ca38 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007fccb1605fa0 RCX: 00007fccb138acb9
RDX: 0000000000000000 RSI: 0000000001001bfc RDI: 0000200000000040
RBP: 00007fccb13f8bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fccb1605fac R14: 00007fccb1605fa0 R15: 00007fccb1605fa0
----------------
Code disassembly (best guess):
0: 90 nop
1: 90 nop
2: 90 nop
3: 90 nop
4: 90 nop
5: 90 nop
6: 90 nop
7: 90 nop
8: 90 nop
9: 41 57 push %r15
b: 41 56 push %r14
d: 41 55 push %r13
f: 41 54 push %r12
11: 53 push %rbx
12: 83 ff dd cmp $0xffffffdd,%edi
15: 0f 85 81 00 00 00 jne 0x9c
1b: 48 89 f7 mov %rsi,%rdi
1e: e8 96 39 01 00 call 0x139b9
23: 48 8d 3d 5f 8c 2f 04 lea 0x42f8c5f(%rip),%rdi # 0x42f8c89
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 4c 8d 3d 00 00 00 00 lea 0x0(%rip),%r15 # 0x36
36: 65 48 8b 1d c3 69 05 mov %gs:0x70569c3(%rip),%rbx # 0x7056a01
3d: 07
3e: 4c rex.WR
3f: 8d .byte 0x8d