INFO: task kworker/u8:1:13 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:1    state:D stack:0     pid:13    tgid:13    ppid:2      flags:0x00004000
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6063 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7883
 __schedule_loop kernel/sched/core.c:7960 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7975
 io_schedule+0x85/0x150 kernel/sched/core.c:8790
 rq_qos_wait+0x25f/0x400 block/blk-rq-qos.c:284
 __wbt_wait block/blk-wbt.c:596 [inline]
 wbt_wait+0x297/0x680 block/blk-wbt.c:661
 __rq_qos_throttle+0x7d/0xd0 block/blk-rq-qos.c:67
 rq_qos_throttle block/blk-rq-qos.h:151 [inline]
 blk_mq_get_new_requests block/blk-mq.c:3081 [inline]
 blk_mq_submit_bio+0xf65/0x2420 block/blk-mq.c:3233
 __submit_bio+0x223/0x9b0 block/blk-core.c:637
 __submit_bio_noacct_mq block/blk-core.c:724 [inline]
 submit_bio_noacct_nocheck+0x496/0xab0 block/blk-core.c:753
 submit_bio_noacct+0xc0e/0x1620 block/blk-core.c:876
 submit_bio+0x424/0x5b0 block/blk-core.c:951
 ext4_io_submit+0xe5/0x150 fs/ext4/page-io.c:389
 ext4_do_writepages+0x2741/0x39f0 fs/ext4/inode.c:2758
 ext4_writepages+0x28c/0x550 fs/ext4/inode.c:2827
 do_writepages+0x3d4/0x7f0 mm/page-writeback.c:2690
 __writeback_single_inode+0xc8/0xba0 fs/fs-writeback.c:1674
 writeback_sb_inodes+0x6a5/0xfb0 fs/fs-writeback.c:1970
 __writeback_inodes_wb+0x129/0x280 fs/fs-writeback.c:2041
 wb_writeback+0x3bb/0x850 fs/fs-writeback.c:2152
 wb_check_old_data_flush fs/fs-writeback.c:2256 [inline]
 wb_do_writeback fs/fs-writeback.c:2309 [inline]
 wb_workfn+0xa03/0xef0 fs/fs-writeback.c:2337
 process_one_work kernel/workqueue.c:3273 [inline]
 process_scheduled_works+0x7f4/0x1060 kernel/workqueue.c:3354
 worker_thread+0xc99/0x13f0 kernel/workqueue.c:3435
 kthread+0x2c4/0x360 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 c2fb930d72f135c881cb4f9a154f1d3dce73421b
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:114
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:63
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 cpumask_backtrace+0x1f/0x30 lib/nmi_backtrace.c:127
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xe45/0xf90 kernel/hung_task.c:423
 kthread+0x2c4/0x360 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 c2fb930d72f135c881cb4f9a154f1d3dce73421b
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:116
Code: cc cc cc cc cc cc cc b8 d6 a7 17 a9 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d c3 e7 41 00 55 48 89 e5 fb f4 <5d> c3 cc cc cc cc cc cc cc cc cc cc cc b8 00 00 00 00 90 90 90 90
RSP: 0018:ffffc900001a7e00 EFLAGS: 000002c2
RAX: ffff8881f6f00000 RBX: ffff888103669300 RCX: ffffffff85a5753d
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 000000000002f604
RBP: ffffc900001a7e00 R08: ffff8881f6f395eb R09: 1ffff1103ede72bd
R10: dffffc0000000000 R11: ffffed103ede72be R12: 0000000000000000
R13: 1ffff110206cd260 R14: dffffc0000000000 R15: ffffffff87ececa8
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f646b738540 CR3: 000000010cf5a000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:-1 [inline]
 default_idle+0x17/0x30 arch/x86/kernel/process.c:754
 arch_cpu_idle+0xd/0x20 arch/x86/kernel/process.c:791
 default_idle_call+0x3e/0x80 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:193 [inline]
 do_idle+0x1df/0x570 kernel/sched/idle.c:346
 cpu_startup_entry+0x47/0x60 kernel/sched/idle.c:445
 start_secondary+0x12e/0x140 arch/x86/kernel/smpboot.c:314
 common_startup_64+0x13b/0x157
 </TASK>