------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: ktimers/0/16
Modules linked in:
CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28
Code: e4 d1 f5 0a 67 48 0f b9 3a eb 4a e8 38 3d 01 fd 48 8d 3d e1 d1 f5 0a 67 48 0f b9 3a eb 37 e8 25 3d 01 fd 48 8d 3d de d1 f5 0a <67> 48 0f b9 3a eb 24 e8 12 3d 01 fd 48 8d 3d db d1 f5 0a 67 48 0f
RSP: 0018:ffffc90000157a28 EFLAGS: 00010246
RAX: ffffffff84c4468b RBX: 0000000000000003 RCX: ffff88801dab8000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffffff8fba1870
RBP: ffffc90000157b30 R08: ffff88801dab8000 R09: 0000000000000005
R10: 0000000000000100 R11: 0000000000000004 R12: 0000000000000000
R13: 00000000ffffe746 R14: ffff8880404e4820 R15: ffff8880404e49b8
FS:  0000000000000000(0000) GS:ffff888125c3c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c36e386 CR3: 0000000029a1e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x67b/0x9b0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
 handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:626
 __do_softirq kernel/softirq.c:660 [inline]
 run_ktimerd+0x69/0x100 kernel/softirq.c:1155
 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:436
 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:	e4 d1                	in     $0xd1,%al
   2:	f5                   	cmc
   3:	0a 67 48             	or     0x48(%rdi),%ah
   6:	0f b9 3a             	ud1    (%rdx),%edi
   9:	eb 4a                	jmp    0x55
   b:	e8 38 3d 01 fd       	call   0xfd013d48
  10:	48 8d 3d e1 d1 f5 0a 	lea    0xaf5d1e1(%rip),%rdi        # 0xaf5d1f8
  17:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1c:	eb 37                	jmp    0x55
  1e:	e8 25 3d 01 fd       	call   0xfd013d48
  23:	48 8d 3d de d1 f5 0a 	lea    0xaf5d1de(%rip),%rdi        # 0xaf5d208
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 24                	jmp    0x55
  31:	e8 12 3d 01 fd       	call   0xfd013d48
  36:	48 8d 3d db d1 f5 0a 	lea    0xaf5d1db(%rip),%rdi        # 0xaf5d218
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf