pktgen: kernel_thread() failed for cpu 0
pktgen: Cannot create thread for cpu 0 (-4)
pktgen: kernel_thread() failed for cpu 1
pktgen: Cannot create thread for cpu 1 (-4)
pktgen: Initialization failed for all threads
INFO: task syz-executor3:13244 blocked for more than 120 seconds.
      Not tainted 4.9.110-g00a0bcb #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor3   D28928 13244   3870 0x00000004
 ffff88019fbb1800 ffff8801d4ca5f80 ffff8801d4ca5f80 ffff8801ce93b000
 ffff8801db221c18 ffff8801a0d4f9f0 ffffffff839e6ded 0000000000000002
 0000000041b58ab3 ffffffff843babdb 00ffffff81221500 ffff8801db2224e8
Call Trace:
 [<ffffffff839e83ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff81e3fa24>] blk_mq_freeze_queue_wait+0x114/0x230 block/blk-mq.c:75
 [<ffffffff81e48d1d>] blk_freeze_queue block/blk-mq.c:92 [inline]
 [<ffffffff81e48d1d>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:101
 [<ffffffff825c94a2>] loop_switch drivers/block/loop.c:599 [inline]
 [<ffffffff825c94a2>] loop_change_fd drivers/block/loop.c:685 [inline]
 [<ffffffff825c94a2>] lo_ioctl+0x722/0x1aa0 drivers/block/loop.c:1350
 [<ffffffff81e55f26>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
 [<ffffffff81e55f26>] blkdev_ioctl+0x7b6/0x1a70 block/ioctl.c:590
 [<ffffffff81632b8e>] block_ioctl+0xde/0x120 fs/block_dev.c:1688
 [<ffffffff815b2b9c>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815b2b9c>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff815b2b9c>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff815b3c1f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815b3c1f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f7cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425cb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3681:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d803c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3777:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f5e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211e1e2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor3/13244:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor3/13260:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor0/13308:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c8e0b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.110-g00a0bcb #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d851fd08 ffffffff81eb2329 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9580 ffff8801d851fd40
 ffffffff81ebd627 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb2329>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb2329>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebd627>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebd5ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9684>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366bc4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366bc4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366bc4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366bc4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f7e9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff839f68f6