INFO: task syz-executor.1:12364 blocked for more than 143 seconds.
      Not tainted 5.3.0-rc3-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D28232 12364   6824 0x00004004
Call Trace:
 context_switch kernel/sched/core.c:3254 [inline]
 __schedule+0x82a/0x18e0 kernel/sched/core.c:3880
 schedule+0x8f/0x260 kernel/sched/core.c:3944
 schedule_timeout+0x5a7/0x9d0 kernel/time/timer.c:1783
 do_wait_for_common kernel/sched/completion.c:83 [inline]
 __wait_for_common kernel/sched/completion.c:104 [inline]
 wait_for_common+0x3ff/0x560 kernel/sched/completion.c:115
 wait_for_completion+0x18/0x20 kernel/sched/completion.c:136
 flush_workqueue+0x35d/0x1350 kernel/workqueue.c:2826
 nbd_start_device_ioctl drivers/block/nbd.c:1254 [inline]
 __nbd_ioctl drivers/block/nbd.c:1329 [inline]
 nbd_ioctl+0x975/0xb40 drivers/block/nbd.c:1369
 __blkdev_driver_ioctl block/ioctl.c:304 [inline]
 blkdev_ioctl+0x998/0x1820 block/ioctl.c:606
 block_ioctl+0xd7/0x130 fs/block_dev.c:1994
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x196/0x1150 fs/ioctl.c:696
 ksys_ioctl+0x62/0x90 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:718
 do_syscall_64+0xd0/0x540 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45dd99
Code: 05 fd 1a 24 00 48 89 04 24 48 c7 44 24 08 10 00 00 00 e8 8a 47 fd ff 90 e8 f4 21 00 00 eb c2 cc cc 64 48 8b 0c 25 f8 ff ff ff <48> 3b 61 10 0f 86 af 01 00 00 48 83 ec 70 48 89 6c 24 68 48 8d 6c
RSP: 002b:00007fb2b14d1c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000012e80 RCX: 000000000045dd99
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 000000000118c000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bfd4
R13: 00007ffd55e555af R14: 00007fb2b14d29c0 R15: 000000000118bfd4
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 PID: 1106 Comm: khungtaskd Not tainted 5.3.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x165/0x21a lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.0+0x49/0x86 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x194/0x1bd lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
 watchdog+0x6a3/0xb60 kernel/hung_task.c:289
 kthread+0x331/0x3f0 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:60