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-executor0:9520 blocked for more than 140 seconds.
      Not tainted 4.9.124-g09eb2ba #31
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D27704  9520  21177 0x00000004
 ffff8801b7174800 ffff8801a4f63480 ffff8801b5045500 ffff8801d91b0000
 ffff8801db221c18 ffff88019f80fb58 ffffffff839f0afd 0000000000000002
 0000000041b58ab3 ffffffff843bbc94 00ffffff81223870 ffff8801db2224e8
Call Trace:
 [<ffffffff839f20ff>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff816073d9>] wb_wait_for_completion+0x149/0x1b0 fs/fs-writeback.c:221
 [<ffffffff8160cb69>] sync_inodes_sb+0x1a9/0x8d0 fs/fs-writeback.c:2412
 [<ffffffff8161ec93>] sync_inodes_one_sb+0x43/0x60 fs/sync.c:73
 [<ffffffff81581590>] iterate_supers+0x130/0x260 fs/super.c:593
 [<ffffffff8161f5a2>] sys_sync+0xa2/0x170 fs/sync.c:112
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a019d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/518:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813689dc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813689dc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81428248>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3780:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839ffba2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff82125402>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor0/9520:
 #0:  (&type->s_umount_key#36){++++..}, at: [<ffffffff81581541>] iterate_supers+0xe1/0x260 fs/super.c:591
1 lock held by syz-executor0/9526:
 #0:  (&type->s_umount_key#36){++++..}, at: [<ffffffff81581541>] iterate_supers+0xe1/0x260 fs/super.c:591

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

NMI backtrace for cpu 0
CPU: 0 PID: 518 Comm: khungtaskd Not tainted 4.9.124-g09eb2ba #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9247d08 ffffffff81eb95e9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9fa0 ffff8801d9247d40
 ffffffff81ec4927 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb95e9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb95e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ec4927>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ec48ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810ba0a4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81368f74>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81368f74>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81368f74>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81368f74>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119f3cd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff83a01b9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6 Comm: kworker/u4:0 Not tainted 4.9.124-g09eb2ba #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn
c (flush-7:0)
c
task: ffff8801d9a38000 task.stack: ffff8801d9a40000
RIP: 0010:[<ffffffff811be1f0>] 
c [<ffffffff811be1f0>] preempt_count_add+0x10/0x170 kernel/sched/core.c:3233
RSP: 0018:ffff8801d9a474d8  EFLAGS: 00000246
RAX: dffffc0000000000 RBX: 0000000000000001 RCX: 1ffffffff0886881
RDX: 0000000000000000 RSI: ffffffff81f2106b RDI: 0000000000000001
RBP: ffff8801d9a474e0 R08: ffff8801d9a38988 R09: 0000000000000001
R10: ffff8801d9a38000 R11: 1ffff1003b34712c R12: ffff8801d5e8e3f0
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8801d5dc4888
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c4293c1010 CR3: 00000001cdb66000 CR4: 00000000001606f0
Stack:
 ffff8801d5e8e3f0
c ffff8801d9a47510
c ffffffff812863e7
c ffff8801d9a47510
c
 ffffea00072e2900
c ffff8801d5e8e3f0
c dffffc0000000000
c ffff8801d9a47520
c
 ffffffff8127e450
c ffff8801d9a47588
c ffffffff8143b3db
c ffffffff8143b090
c
Call Trace:
 [<ffffffff812863e7>] rcu_lockdep_current_cpu_online+0x37/0x140 kernel/rcu/tree.c:1104
 [<ffffffff8127e450>] rcu_read_lock_held+0x90/0xc0 kernel/rcu/update.c:295
 [<ffffffff8143b3db>] radix_tree_deref_slot include/linux/radix-tree.h:199 [inline]
 [<ffffffff8143b3db>] find_get_entry+0x34b/0x540 mm/filemap.c:1095
 [<ffffffff8143c50b>] pagecache_get_page+0x4b/0x720 mm/filemap.c:1201
 [<ffffffff81628732>] find_get_page_flags include/linux/pagemap.h:264 [inline]
 [<ffffffff81628732>] __find_get_block_slow+0xc2/0x330 fs/buffer.c:212
 [<ffffffff81628cde>] __find_get_block+0x23e/0x4c0 fs/buffer.c:1360
 [<ffffffff81629ae9>] __getblk_slow fs/buffer.c:1101 [inline]
 [<ffffffff81629ae9>] __getblk_gfp+0x189/0x710 fs/buffer.c:1386
 [<ffffffff8162d48d>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818db771>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818db771>] fat_clusters_flush+0x111/0x380 fs/fat/misc.c:69
 [<ffffffff818d56d2>] fat_write_inode+0xf2/0x170 fs/fat/inode.c:898
 [<ffffffff81606add>] write_inode fs/fs-writeback.c:1180 [inline]
 [<ffffffff81606add>] __writeback_single_inode+0x86d/0x1020 fs/fs-writeback.c:1379
 [<ffffffff81607ddc>] writeback_sb_inodes+0x4ac/0xe70 fs/fs-writeback.c:1584
 [<ffffffff8160889b>] __writeback_inodes_wb+0xfb/0x1e0 fs/fs-writeback.c:1653
 [<ffffffff81609022>] wb_writeback+0x512/0xbd0 fs/fs-writeback.c:1762
 [<ffffffff81612950>] wb_check_old_data_flush fs/fs-writeback.c:1877 [inline]
 [<ffffffff81612950>] wb_do_writeback fs/fs-writeback.c:1901 [inline]
 [<ffffffff81612950>] wb_workfn+0x850/0xdb0 fs/fs-writeback.c:1930
 [<ffffffff8118f461>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff81190256>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119f3cd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff83a01b9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Code: 
c6d 
c03 
c00 
c00 
c48 
cc7 
cc7 
c60 
c74 
cc5 
c83 
cc6 
c05 
c6d 
cd2 
ca8 
c03 
c01 
ce8 
c74 
c73 
c07 
c00 
cc9 
cc3 
c66 
c90 
c48 
cb8 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
c55 
c48 
c89 
ce5 
c41 
c54 
c<53> 
c89 
cfb 
c48 
cc7 
cc7 
c80 
cf6 
cb2 
c85 
c48 
c89 
cfa 
c48 
cc1 
cea 
c03 
c0f 
cb6 
c14 
c02 
c