IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
INFO: task syz-executor0:8666 blocked for more than 120 seconds.
      Not tainted 4.9.111-g03c70fe #5
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D28712  8666   1592 0x00000004
 ffff8801c97fe000 ffff8801b4730540 ffff8801b4730540 ffff88019fe99800
 ffff8801db221c18 ffff88019fbffce8 ffffffff839e7ded ffff8801c97fe8c8
 ffffed00392ffd18 ffff8801c97fe000 00fffc0000000000 ffff8801db2224e8
Call Trace:
 [<ffffffff839e93ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839e9d73>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590
 [<ffffffff839ee1f6>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839ee1f6>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff815d810c>] __fdget_pos+0xac/0xd0 fs/file.c:781
 [<ffffffff815767fe>] fdget_pos include/linux/file.h:66 [inline]
 [<ffffffff815767fe>] SYSC_write fs/read_write.c:599 [inline]
 [<ffffffff815767fe>] SyS_write+0x7e/0x1c0 fs/read_write.c:596
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f8cd3>] 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: [<ffffffff813666fc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813666fc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425d87>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3681:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d810c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3777:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211e602>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor0/8666:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d810c>] __fdget_pos+0xac/0xd0 fs/file.c:781

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.111-g03c70fe #5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d86ffd08 ffffffff81eb2729 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9af0 ffff8801d86ffd40
 ffffffff81ebda27 0000000000000000 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb2729>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb2729>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebda27>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebd9ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9bf4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366c94>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366c94>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366c94>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366c94>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d05d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f8e9c>] 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: 5192 Comm: kworker/u4:7 Not tainted 4.9.111-g03c70fe #5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn
c (flush-7:0)
c
task: ffff88019ae7c800 task.stack: ffff88019af08000
RIP: 0010:[<ffffffff8127beeb>] 
c [<ffffffff8127beeb>] debug_lockdep_rcu_enabled+0x3b/0x90 kernel/rcu/update.c:264
RSP: 0018:ffff88019af0f460  EFLAGS: 00000202
RAX: 0000000000000007 RBX: ffff8801d5d93188 RCX: 0000000000000006
RDX: 0000000000000002 RSI: ffffffff81438f12 RDI: ffffffff84c5e6c4
RBP: ffff88019af0f460 R08: ffff88019ae7d160 R09: 0000000000000001
R10: ffff88019ae7c800 R11: 1ffff100335cfa27 R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8801d5d93188
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c427231010 CR3: 00000001d52e0000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffff88019af0f4c8
c ffffffff81438f17
c ffffffff81438b80
c ffffed00335cfa18
c
 ffff88019ae7d0c8
c 0000000000000041
c ffff8801d5d93190
c 0000000000000000
c
 ffff8801d5d93188
c 0000000000000001
c dffffc0000000000
c 0000000000000000
c
Call Trace:
 [<ffffffff81438f17>] rcu_read_unlock include/linux/rcupdate.h:927 [inline]
 [<ffffffff81438f17>] find_get_entry+0x397/0x540 mm/filemap.c:1132
 [<ffffffff81439ffb>] pagecache_get_page+0x4b/0x720 mm/filemap.c:1203
 [<ffffffff81623f02>] find_get_page_flags include/linux/pagemap.h:264 [inline]
 [<ffffffff81623f02>] __find_get_block_slow+0xc2/0x330 fs/buffer.c:212
 [<ffffffff816244ae>] __find_get_block+0x23e/0x4c0 fs/buffer.c:1360
 [<ffffffff816252b9>] __getblk_slow fs/buffer.c:1101 [inline]
 [<ffffffff816252b9>] __getblk_gfp+0x189/0x710 fs/buffer.c:1386
 [<ffffffff81628c5d>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818cbbdb>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818cbbdb>] __fat_write_inode+0x2ab/0x980 fs/fat/inode.c:844
 [<ffffffff818cfde9>] fat_write_inode+0x79/0x170 fs/fat/inode.c:893
 [<ffffffff816022ad>] write_inode fs/fs-writeback.c:1180 [inline]
 [<ffffffff816022ad>] __writeback_single_inode+0x86d/0x1020 fs/fs-writeback.c:1379
 [<ffffffff816035ac>] writeback_sb_inodes+0x4ac/0xe70 fs/fs-writeback.c:1584
 [<ffffffff8160406b>] __writeback_inodes_wb+0xfb/0x1e0 fs/fs-writeback.c:1653
 [<ffffffff816047f2>] wb_writeback+0x512/0xbd0 fs/fs-writeback.c:1762
 [<ffffffff8160e120>] wb_check_old_data_flush fs/fs-writeback.c:1877 [inline]
 [<ffffffff8160e120>] wb_do_writeback fs/fs-writeback.c:1901 [inline]
 [<ffffffff8160e120>] wb_workfn+0x850/0xdb0 fs/fs-writeback.c:1930
 [<ffffffff8118d131>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118df26>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119d05d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f8e9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Code: 
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