blk_update_request: I/O error, dev nbd4, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
Buffer I/O error on dev nbd4, logical block 0, async page read
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 150 at lib/refcount.c:28 refcount_warn_saturate+0x11b/0x1a0 lib/refcount.c:28
Modules linked in:
CPU: 0 PID: 150 Comm: kworker/0:1H Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: kblockd blk_mq_run_work_fn
RIP: 0010:refcount_warn_saturate+0x11b/0x1a0 lib/refcount.c:28
Code: 09 01 48 c7 c7 20 b9 79 8a e8 41 70 cd 05 0f 0b eb c4 e8 18 59 95 fd c6 05 a4 6b 92 09 01 48 c7 c7 80 b9 79 8a e8 25 70 cd 05 <0f> 0b eb a8 e8 fc 58 95 fd c6 05 85 6b 92 09 01 48 c7 c7 c0 b8 79
RSP: 0018:ffffc9000180f7e8 EFLAGS: 00010246
RAX: b286156e806b8300 RBX: 0000000000000003 RCX: ffff88801becbb80
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000180f990 R08: ffffc9000180f307 R09: 1ffff92000301e60
R10: dffffc0000000000 R11: fffff52000301e61 R12: dffffc0000000000
R13: 1ffff11004241049 R14: 0000000000000003 R15: ffff8880210dd000
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3261fff8 CR3: 0000000078e3c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 000000000000000e DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 blk_mq_end_request block/blk-mq.c:578 [inline]
 blk_mq_dispatch_rq_list+0xba3/0x1d40 block/blk-mq.c:1409
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:200 [inline]
 blk_mq_do_dispatch_sched+0xae2/0xc90 block/blk-mq-sched.c:214
 __blk_mq_sched_dispatch_requests+0x2f3/0x410 block/blk-mq-sched.c:340
 blk_mq_sched_dispatch_requests+0xf4/0x1b0 block/blk-mq-sched.c:366
 __blk_mq_run_hw_queue+0xbb/0x100 block/blk-mq.c:1512
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>