syzbot


WARNING in filename_unlinkat

Status: moderation: reported on 2026/04/30 07:10
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+d7ea8f71e1a0d4ef32a0@syzkaller.appspotmail.com
First crash: 6d10h, last: 6d10h

Sample crash report:
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current)
WARNING: kernel/locking/rtmutex_common.h:193 at debug_rt_mutex_unlock kernel/locking/rtmutex_common.h:193 [inline], CPU#1: syz.5.454/8093
WARNING: kernel/locking/rtmutex_common.h:193 at rt_mutex_slowunlock+0x6d9/0x8b0 kernel/locking/rtmutex.c:1428, CPU#1: syz.5.454/8093
Modules linked in:
CPU: 1 UID: 0 PID: 8093 Comm: syz.5.454 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:debug_rt_mutex_unlock kernel/locking/rtmutex_common.h:193 [inline]
RIP: 0010:rt_mutex_slowunlock+0x6e0/0x8b0 kernel/locking/rtmutex.c:1428
Code: 88 8f 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 c0 01 00 00 83 3d 74 4a 6b 04 00 75 13 48 8d 3d c7 58 6e 04 48 c7 c6 e0 f2 4c 8b <67> 48 0f b9 3a 90 e9 2a fa ff ff 90 0f 0b 90 e9 4c fe ff ff be 02
RSP: 0000:ffffc9000df67cc0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff888061a47588 RCX: 0000000000080000
RDX: ffffc9001c77a000 RSI: ffffffff8b4cf2e0 RDI: ffffffff8f8bf270
RBP: ffffc9000df67db0 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f11c83 R12: dffffc0000000000
R13: 1ffff92001becfa0 R14: 0000000000000246 R15: ffff888061a47538
FS:  00007f6d907bd6c0(0000) GS:ffff88812627d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdac1481000 CR3: 0000000060c5e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 inode_unlock include/linux/fs.h:1039 [inline]
 __start_dirop fs/namei.c:2918 [inline]
 start_dirop fs/namei.c:2938 [inline]
 filename_unlinkat+0x4ce/0x610 fs/namei.c:5549
 __do_sys_unlinkat fs/namei.c:5597 [inline]
 __se_sys_unlinkat+0x83/0x1a0 fs/namei.c:5589
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6d9258cdd9
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:00007f6d907bd028 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f6d92806090 RCX: 00007f6d9258cdd9
RDX: 0000000000000000 RSI: 0000200000000140 RDI: ffffffffffffff9c
RBP: 00007f6d92622d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6d92806128 R14: 00007f6d92806090 R15: 00007ffdd72eda08
 </TASK>
----------------
Code disassembly (best guess):
   0:	88 8f 48 c1 e8 03    	mov    %cl,0x3e8c148(%rdi)
   6:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax
   b:	84 c0                	test   %al,%al
   d:	0f 85 c0 01 00 00    	jne    0x1d3
  13:	83 3d 74 4a 6b 04 00 	cmpl   $0x0,0x46b4a74(%rip)        # 0x46b4a8e
  1a:	75 13                	jne    0x2f
  1c:	48 8d 3d c7 58 6e 04 	lea    0x46e58c7(%rip),%rdi        # 0x46e58ea
  23:	48 c7 c6 e0 f2 4c 8b 	mov    $0xffffffff8b4cf2e0,%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	90                   	nop
  30:	e9 2a fa ff ff       	jmp    0xfffffa5f
  35:	90                   	nop
  36:	0f 0b                	ud2
  38:	90                   	nop
  39:	e9 4c fe ff ff       	jmp    0xfffffe8a
  3e:	be                   	.byte 0xbe
  3f:	02                   	.byte 0x2

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/26 07:06 upstream 897d54018cc9 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in filename_unlinkat
* Struck through repros no longer work on HEAD.