syzbot

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refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 20 at lib/refcount.c:28 refcount_warn_saturate+0x11b/0x1a0 lib/refcount.c:28
Modules linked in:
CPU: 1 PID: 20 Comm: ksoftirqd/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:refcount_warn_saturate+0x11b/0x1a0 lib/refcount.c:28
Code: 09 01 48 c7 c7 e0 67 59 8a e8 d1 91 c3 05 0f 0b eb c4 e8 28 f4 9c fd c6 05 7f 1a 7b 09 01 48 c7 c7 40 68 59 8a e8 b5 91 c3 05 <0f> 0b eb a8 e8 0c f4 9c fd c6 05 60 1a 7b 09 01 48 c7 c7 80 67 59
RSP: 0018:ffffc90000da7c78 EFLAGS: 00010246

RAX: 1708c79c29411400 RBX: 0000000000000003 RCX: ffff888016a90000
RDX: 0000000000000100 RSI: 0000000000000100 RDI: 0000000000000000
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff1ad32b6
R10: fffffbfff1ad32b6 R11: 1ffffffff1ad32b5 R12: dffffc0000000000
R13: 0000000000000005 R14: 0000000000000003 R15: ffffffff8a7ca320
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c006cc3000 CR3: 000000007a5ea000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 blk_complete_reqs block/blk-mq.c:587 [inline]
 blk_done_softirq+0xfa/0x140 block/blk-mq.c:592
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 run_ksoftirqd+0x98/0xf0 kernel/softirq.c:943
 smpboot_thread_fn+0x4f6/0x970 kernel/smpboot.c:164
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>