[syzbot] [gfs2?] WARNING: kobject bug in __dlm_new_lockspace

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8d3ae59288f1 Linux 7.2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=144ed6c6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4c9eb8e593cf8c5c
dashboard link: https://syzkaller.appspot.com/bug?extid=b2b8d04ec4914f618d23
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e3213198af93/disk-8d3ae592.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ccb0eb1c86ad/vmlinux-8d3ae592.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8c009fbdf753/bzImage-8d3ae592.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b2b8d0...@syzkaller.appspotmail.com

dlm: Using TCP for communications
workqueue: Failed to create a rescuer kthread for wq "dlm_callback": -EINTR
dlm: can't start dlm_callback workqueue
dlm: mydomain: can't start dlm_callback -12
------------[ cut here ]------------
kobject: '(null)' (ffff888060a7c0c8): 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.2.3/5785
Modules linked in:
CPU: 1 UID: 0 PID: 5785 Comm: syz.2.3 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: 85 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 2b 7e f3 f6 48 8b 33 4c 89 f7 48 89 da <67> 48 0f b9 3a eb 05 e8 f6 f9 89 f6 4c 8d 73 38 4c 89 f7 be 04 00
RSP: 0018:ffffc90004347810 EFLAGS: 00010246
RAX: 1ffff1100c14f819 RBX: ffff888060a7c0c8 RCX: dffffc0000000000
RDX: ffff888060a7c0c8 RSI: 0000000000000000 RDI: ffffffff8fc1a5a0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f5f267 R12: 1ffff1100c14f820
R13: 00000000fffffff4 R14: ffffffff8fc1a5a0 R15: ffff888060a7c000
FS: 00007f3edfd866c0(0000) GS:ffff888125d3a000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff044558000 CR3: 000000003c66c000 CR4: 00000000003526f0
Call Trace:
<TASK>
new_lockspace fs/dlm/lockspace.c:617 [inline]
__dlm_new_lockspace+0x19f0/0x2060 fs/dlm/lockspace.c:638
user_cluster_connect+0x231/0xcc0 fs/ocfs2/stack_user.c:976
ocfs2_cluster_connect+0x445/0x720 fs/ocfs2/stackglue.c:355
ocfs2_cluster_connect_agnostic+0x6e/0x90 fs/ocfs2/stackglue.c:385
user_dlm_register+0xd2/0x210 fs/ocfs2/dlmfs/userdlm.c:669
dlmfs_mkdir+0x13c/0x340 fs/ocfs2/dlmfs/dlmfs.c:434
vfs_mkdir+0x402/0x620 fs/namei.c:5276
filename_mkdirat+0x289/0x520 fs/namei.c:5309
__do_sys_mkdir fs/namei.c:5336 [inline]
__se_sys_mkdir+0x34/0x150 fs/namei.c:5333
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3ee1b2e0d9
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:00007f3edfd86028 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007f3ee1db5fa0 RCX: 00007f3ee1b2e0d9
RDX: 0000000000000000 RSI: 00000000000001ff RDI: 00002000000006c0
RBP: 00007f3ee1bc5024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3ee1db6038 R14: 00007f3ee1db5fa0 R15: 00007ffc09922098
</TASK>
----------------
Code disassembly (best guess):
0: 85 04 48 test %eax,(%rax,%rcx,2)
3: 89 d8 mov %ebx,%eax
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 2b 7e f3 f6 call 0xf6f37e4c
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 f6 f9 89 f6 call 0xf689fa2c
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


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