blk_update_request: I/O error, dev nbd0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0 Buffer I/O error on dev nbd0, logical block 0, async page read ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 227 at lib/refcount.c:28 refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 Modules linked in: CPU: 1 PID: 227 Comm: kworker/1:1H Not tainted 5.15.189-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: kblockd blk_mq_run_work_fn pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 lr : refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 sp : ffff80001bf575c0 x29: ffff80001bf575c0 x28: fffffbffefff1500 x27: 1fffe000198bbf83 x26: 1fffe000198bbf83 x25: 0000000000000000 x24: 0000000000000001 x23: dfff800000000000 x22: fffffbffefff15c8 x21: 0000000000000000 x20: ffff0000cc5dfce8 x19: ffff8000165b2000 x18: 0000000000000001 x17: 0000000000000000 x16: ffff8000083020fc x15: 00000000ffffffff x14: 0000000000ff0100 x13: 0000000000000001 x12: 0000000000ff0100 x11: 0000000000000000 x10: 0000000000000000 x9 : 28f40d3e30e00100 x8 : 28f40d3e30e00100 x7 : 0000000000000001 x6 : 0000000000000001 x5 : ffff80001bf56eb8 x4 : ffff80001424f400 x3 : ffff80000830220c x2 : 0000000000000001 x1 : 0000000100000000 x0 : 0000000000000026 Call trace: refcount_warn_saturate+0x154/0x1f8 lib/refcount.c:28 __refcount_sub_and_test include/linux/refcount.h:283 [inline] __refcount_dec_and_test include/linux/refcount.h:315 [inline] refcount_dec_and_test include/linux/refcount.h:333 [inline] blk_mq_free_request+0x434/0x578 block/blk-mq.c:543 __blk_mq_end_request+0x30c/0x344 block/blk-mq.c:568 blk_mq_end_request block/blk-mq.c:577 [inline] blk_mq_dispatch_rq_list+0x960/0x13c8 block/blk-mq.c:1408 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:200 [inline] blk_mq_do_dispatch_sched+0x7e8/0x92c block/blk-mq-sched.c:214 __blk_mq_sched_dispatch_requests+0x2c4/0x3cc block/blk-mq-sched.c:-1 blk_mq_sched_dispatch_requests+0xc4/0x174 block/blk-mq-sched.c:366 __blk_mq_run_hw_queue block/blk-mq.c:1511 [inline] blk_mq_run_work_fn+0xfc/0x19c block/blk-mq.c:1848 process_one_work+0x79c/0x1140 kernel/workqueue.c:2310 worker_thread+0x8f4/0x101c kernel/workqueue.c:2457 kthread+0x374/0x454 kernel/kthread.c:334 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:855 irq event stamp: 52980 hardirqs last enabled at (52979): [] __up_console_sem+0xb4/0x100 kernel/printk/printk.c:257 hardirqs last disabled at (52980): [] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:396 softirqs last enabled at (52950): [] softirq_handle_end kernel/softirq.c:419 [inline] softirqs last enabled at (52950): [] handle_softirqs+0xa4c/0xbf0 kernel/softirq.c:604 softirqs last disabled at (52739): [] __do_softirq kernel/softirq.c:610 [inline] softirqs last disabled at (52739): [] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline] softirqs last disabled at (52739): [] invoke_softirq kernel/softirq.c:457 [inline] softirqs last disabled at (52739): [] __irq_exit_rcu+0x240/0x440 kernel/softirq.c:659 ---[ end trace 71062e79568bfe12 ]--- blk_update_request: I/O error, dev nbd0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0 Buffer I/O error on dev nbd0, logical block 0, async page read blk_update_request: I/O error, dev nbd1, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0 Buffer I/O error on dev nbd1, logical block 0, async page read blk_update_request: I/O error, dev nbd1, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0 Buffer I/O error on dev nbd1, logical block 0, async page read