------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 3 PID: 0 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Modules linked in:
CPU: 3 UID: 0 PID: 0 Comm: swapper/3 Not tainted 6.15.0-rc7-syzkaller-00014-gd608703fcdd9 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28
Code: ff 89 de e8 38 19 ea fc 84 db 0f 85 66 ff ff ff e8 4b 1e ea fc c6 05 1d 75 9c 0b 01 90 48 c7 c7 a0 4e f4 8b e8 a7 ab a9 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 28 1e ea fc 0f b6 1d f8 74 9c 0b 31
RSP: 0018:ffffc900006f8d90 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff817ad4f8
RDX: ffff88801daf0000 RSI: ffffffff817ad505 RDI: 0000000000000001
RBP: ffff88805031f768 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88805031f768
R13: ffff888048851000 R14: 0000000000000015 R15: 1ffff1102186680c
FS:  0000000000000000(0000) GS:ffff8880d6cda000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000000f000 CR3: 000000002707e000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __refcount_sub_and_test include/linux/refcount.h:400 [inline]
 __refcount_dec_and_test include/linux/refcount.h:432 [inline]
 refcount_dec_and_test include/linux/refcount.h:450 [inline]
 p9_req_put+0x1ec/0x250 net/9p/client.c:404
 req_done+0x1dc/0x2e0 net/9p/trans_virtio.c:147
 vring_interrupt drivers/virtio/virtio_ring.c:2715 [inline]
 vring_interrupt+0x31e/0x400 drivers/virtio/virtio_ring.c:2690
 __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
 handle_edge_irq+0x263/0xd10 kernel/irq/chip.c:831
 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
 handle_irq arch/x86/kernel/irq.c:254 [inline]
 call_irq_handler arch/x86/kernel/irq.c:266 [inline]
 __common_interrupt+0xe2/0x250 arch/x86/kernel/irq.c:292
 common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285
 </IRQ>
 <TASK>
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
RIP: 0010:finish_task_switch.isra.0+0x22a/0xc10 kernel/sched/core.c:5250
Code: fb 09 00 00 44 8b 05 49 cb fb 0e 45 85 c0 0f 85 be 01 00 00 4c 89 e7 e8 a4 f6 ff ff e8 ff 77 39 00 fb 65 48 8b 1d 8e cd 1a 12 <48> 8d bb 18 16 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1
RSP: 0018:ffffc90000197be0 EFLAGS: 00000206
RAX: 000000000029443f RBX: ffff88801daf0000 RCX: ffffffff81c3097f
RDX: 0000000000000000 RSI: ffffffff8dbe4615 RDI: ffffffff8bf4a2a0
RBP: ffffc90000197c28 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff90852e17 R11: 0000000000000000 R12: ffff88806a739dc0
R13: ffff88804457a440 R14: ffff88802ae38000 R15: ffff88806a73abf0
 context_switch kernel/sched/core.c:5385 [inline]
 __schedule+0x1177/0x5de0 kernel/sched/core.c:6767
 schedule_idle+0x5c/0x90 kernel/sched/core.c:6886
 do_idle+0x2b6/0x510 kernel/sched/idle.c:353
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423
 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315
 common_startup_64+0x13e/0x148
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	00 00                	add    %al,(%rax)
   2:	44 8b 05 49 cb fb 0e 	mov    0xefbcb49(%rip),%r8d        # 0xefbcb52
   9:	45 85 c0             	test   %r8d,%r8d
   c:	0f 85 be 01 00 00    	jne    0x1d0
  12:	4c 89 e7             	mov    %r12,%rdi
  15:	e8 a4 f6 ff ff       	call   0xfffff6be
  1a:	e8 ff 77 39 00       	call   0x39781e
  1f:	fb                   	sti
  20:	65 48 8b 1d 8e cd 1a 	mov    %gs:0x121acd8e(%rip),%rbx        # 0x121acdb6
  27:	12
* 28:	48 8d bb 18 16 00 00 	lea    0x1618(%rbx),%rdi <-- trapping instruction
  2f:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  36:	fc ff df
  39:	48 89 fa             	mov    %rdi,%rdx
  3c:	48                   	rex.W
  3d:	c1                   	.byte 0xc1