dlm: dlm1: join complete
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x111/0x130 lib/refcount.c:25, CPU#0: syz.3.28/5936
Modules linked in:
CPU: 0 UID: 0 PID: 5936 Comm: syz.3.28 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:refcount_warn_saturate+0x111/0x130 lib/refcount.c:25
Code: fb e8 33 df e2 fc 48 8d 3d 3c 33 27 0c 67 48 0f b9 3a e8 22 df e2 fc 5b 5d e9 36 51 e7 fb e8 16 df e2 fc 48 8d 3d 2f 33 27 0c <67> 48 0f b9 3a e8 05 df e2 fc 5b 5d e9 19 51 e7 fb 48 89 df e8 26
RSP: 0018:ffffc90004f07b00 EFLAGS: 00010287
RAX: 00000000000008e1 RBX: ffff888048c2c130 RCX: ffffc9000f446000
RDX: 0000000000080000 RSI: ffffffff8528efda RDI: ffffffff91502310
RBP: 0000000000000002 R08: 0000000000000005 R09: 0000000000000004
R10: 0000000000000002 R11: 0000000000000000 R12: ffff8880223d6000
R13: 0000000000000000 R14: ffff888048c2c130 R15: 0000000000000000
FS:  00007f0691f816c0(0000) GS:ffff888123b61000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555584047a38 CR3: 000000006452d000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:289 [inline]
 __refcount_inc include/linux/refcount.h:366 [inline]
 refcount_inc include/linux/refcount.h:383 [inline]
 kref_get include/linux/kref.h:45 [inline]
 hold_lkb fs/dlm/lock.c:1618 [inline]
 dlm_user_request+0x5bb/0x690 fs/dlm/lock.c:5788
 device_user_lock fs/dlm/user.c:288 [inline]
 device_write+0x1703/0x1c90 fs/dlm/user.c:582
 vfs_write+0x2aa/0x1050 fs/read_write.c:685
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f069119e159
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:00007f0691f81028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f0691426180 RCX: 00007f069119e159
RDX: 000000000000007c RSI: 0000200000000200 RDI: 0000000000000009
RBP: 00007f0691235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0691426218 R14: 00007f0691426180 R15: 00007ffeb1569d48
 </TASK>
----------------
Code disassembly (best guess):
   0:	fb                   	sti
   1:	e8 33 df e2 fc       	call   0xfce2df39
   6:	48 8d 3d 3c 33 27 0c 	lea    0xc27333c(%rip),%rdi        # 0xc273349
   d:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  12:	e8 22 df e2 fc       	call   0xfce2df39
  17:	5b                   	pop    %rbx
  18:	5d                   	pop    %rbp
  19:	e9 36 51 e7 fb       	jmp    0xfbe75154
  1e:	e8 16 df e2 fc       	call   0xfce2df39
  23:	48 8d 3d 2f 33 27 0c 	lea    0xc27332f(%rip),%rdi        # 0xc273359
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e8 05 df e2 fc       	call   0xfce2df39
  34:	5b                   	pop    %rbx
  35:	5d                   	pop    %rbp
  36:	e9 19 51 e7 fb       	jmp    0xfbe75154
  3b:	48 89 df             	mov    %rbx,%rdi
  3e:	e8                   	.byte 0xe8
  3f:	26                   	es