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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 848acc8ffe1b Merge tag 'fsverity-for-linus' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=134db649580000
kernel config: https://syzkaller.appspot.com/x/.config?x=cb17729fb04b1e3a
dashboard link: https://syzkaller.appspot.com/bug?extid=fdbfc0c2425fb3e2280b
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [aahr...@redhat.com gf...@lists.linux.dev linux-...@vger.kernel.org teig...@redhat.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/375d27e96ecb/disk-848acc8f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4ba19a656b9d/vmlinux-848acc8f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7c2a17aaee7c/bzImage-848acc8f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fdbfc0...@syzkaller.appspotmail.com

dlm: myls: can't start dlm_recoverd -4
------------[ cut here ]------------
kobject: '(null)' (ffff88802c5000c8): 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: iou-wrk-5931/5942
Modules linked in:
CPU: 1 UID: 0 PID: 5942 Comm: iou-wrk-5931 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: 87 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 be f4 f6 48 8b 33 4c 89 f7 48 89 da <67> 48 0f b9 3a eb 05 e8 86 4a 8b f6 4c 8d 73 38 4c 89 f7 be 04 00
RSP: 0018:ffffc90005fe7610 EFLAGS: 00010246
RAX: 1ffff110058a0019 RBX: ffff88802c5000c8 RCX: dffffc0000000000
RDX: ffff88802c5000c8 RSI: 0000000000000000 RDI: ffffffff8fc1aca0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f5f467 R12: 1ffff110058a0020
R13: 00000000fffffffc R14: ffffffff8fc1aca0 R15: ffff88802c500000
FS: 00007f8190b556c0(0000) GS:ffff888125d3e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f80f84c3286 CR3: 000000002bbfc000 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
loop_rw_iter+0x42f/0x6a0 include/linux/uio.h:-1
io_write+0x11e6/0x1690 io_uring/rw.c:1184
__io_issue_sqe+0x188/0x4d0 io_uring/io_uring.c:1395
io_issue_sqe+0x16d/0x1020 io_uring/io_uring.c:1418
io_wq_submit_work+0x7b4/0xca0 io_uring/io_uring.c:1534
io_worker_handle_work+0x72e/0x10e0 io_uring/io-wq.c:652
io_wq_worker+0x452/0xf10 io_uring/io-wq.c:706
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
----------------
Code disassembly (best guess):
0: 87 04 48 xchg %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 be f4 f6 call 0xf6f4be4c
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 86 4a 8b f6 call 0xf68b4abc
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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