WARNING: kobject bug in __dlm_new_lockspace

Status: upstream: reported on 2026/08/17 08:57
Subsystems: gfs2
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+b2b8d04ec4914f618d23@syzkaller.appspotmail.com
First crash: 41d, last: 8d00h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
2d44ae19 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING: kobject bug in __dlm_new_lockspace 2026/08/03 01:25 2026/08/03 01:25 2026/08/03 01:30 e611ffe1
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [gfs2?] WARNING: kobject bug in __dlm_new_lockspace 0 (1) 2026/08/17 08:57

Sample crash report:
dlm: ls1: can't start dlm_recoverd -4
------------[ cut here ]------------
kobject: '(null)' (ffff8880370e40c8): is not initialized, yet kobject_put() is being called.
WARNING: lib/kobject.c:736 at kobject_put+0x66/0x550 lib/kobject.c:734, CPU#1: syz.8.511/8761
Modules linked in:
CPU: 1 UID: 0 PID: 8761 Comm: syz.8.511 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:kobject_put+0x8e/0x550 lib/kobject.c:734
Code: 77 04 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 48 89 df e8 db 29 e6 f6 48 8b 33 4c 89 f7 48 89 da <67> 48 0f b9 3a eb 05 e8 06 7b 7a f6 4c 8d 73 38 4c 89 f7 be 04 00
RSP: 0018:ffffc9000485f9f0 EFLAGS: 00010246
RAX: 1ffff11006e1c819 RBX: ffff8880370e40c8 RCX: dffffc0000000000
RDX: ffff8880370e40c8 RSI: 0000000000000000 RDI: ffffffff8fc3b1e0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f63bb0 R12: 1ffff11006e1c820
R13: 00000000fffffffc R14: ffffffff8fc3b1e0 R15: ffff8880370e4000
FS:  00007fc8d9d656c0(0000) GS:ffff888125cd5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6f1eb90a10 CR3: 000000005d6cc000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 new_lockspace fs/dlm/lockspace.c:617 [inline]
 __dlm_new_lockspace+0x19f0/0x2060 fs/dlm/lockspace.c:638
 device_create_lockspace+0xc7/0x350 fs/dlm/user.c:414
 device_write+0x875/0xed0 fs/dlm/user.c:606
 vfs_write+0x29f/0xbb0 fs/read_write.c:685
 ksys_write+0x156/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc8dbb2e159
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:00007fc8d9d65028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc8dbdb6090 RCX: 00007fc8dbb2e159
RDX: 0000000000000078 RSI: 00002000000003c0 RDI: 0000000000000005
RBP: 00007fc8dbbc5024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc8dbdb6128 R14: 00007fc8dbdb6090 R15: 00007ffddf8605f8
 </TASK>
----------------
Code disassembly (best guess):
   0:	77 04                	ja     0x6
   2:	48 89 d8             	mov    %rbx,%rax
   5:	48 c1 e8 03          	shr    $0x3,%rax
   9:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  10:	fc ff df
  13:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1)
  17:	74 08                	je     0x21
  19:	48 89 df             	mov    %rbx,%rdi
  1c:	e8 db 29 e6 f6       	call   0xf6e629fc
  21:	48 8b 33             	mov    (%rbx),%rsi
  24:	4c 89 f7             	mov    %r14,%rdi
  27:	48 89 da             	mov    %rbx,%rdx
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 05                	jmp    0x36
  31:	e8 06 7b 7a f6       	call   0xf67a7b3c
  36:	4c 8d 73 38          	lea    0x38(%rbx),%r14
  3a:	4c 89 f7             	mov    %r14,%rdi
  3d:	be                   	.byte 0xbe
  3e:	04 00                	add    $0x0,%al

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/03 18:34 upstream 8ab1afb2eb24 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING: kobject bug in __dlm_new_lockspace
2026/09/03 18:33 upstream 8ab1afb2eb24 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING: kobject bug in __dlm_new_lockspace
2026/08/17 10:18 upstream 8d3ae59288f1 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING: kobject bug in __dlm_new_lockspace
2026/08/17 10:09 upstream 8d3ae59288f1 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING: kobject bug in __dlm_new_lockspace
2026/08/17 08:56 upstream 8d3ae59288f1 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING: kobject bug in __dlm_new_lockspace
2026/08/13 19:06 upstream 3aa1dcaa4f6f b13552fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING: kobject bug in __dlm_new_lockspace
2026/08/04 14:51 upstream 848acc8ffe1b d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING: kobject bug in __dlm_new_lockspace
2026/08/01 05:52 upstream 0131b508c0e2 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING: kobject bug in __dlm_new_lockspace
2026/09/03 15:21 upstream 940de590b839 a8a356ea .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: kobject bug in __dlm_new_lockspace
2026/08/08 09:31 upstream 3f008280327b 5d63f80b .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING: kobject bug in __dlm_new_lockspace
* Struck through repros no longer work on HEAD.