device lo left promiscuous mode
device lo left promiscuous mode
INFO: task syz-executor0:3826 blocked for more than 140 seconds.
      Not tainted 4.9.111-g03c70fe #6
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D27640  3826      1 0x00000004
 ffff8801bbc20000 0000000000000000 ffff8801bcf56a00 ffff8801c4a13000
 ffff8801db321c18 ffff8801aeb47b40 ffffffff839e7ded 0000000000000002
 0000000041b58ab3 ffffffff843bac1b 00ffffff81221510 ffff8801db3224e8
Call Trace:
 [<ffffffff839e93ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff81602ba9>] wb_wait_for_completion+0x149/0x1b0 fs/fs-writeback.c:221
 [<ffffffff81602e17>] __writeback_inodes_sb_nr+0x207/0x300 fs/fs-writeback.c:2310
 [<ffffffff81602f67>] writeback_inodes_sb_nr fs/fs-writeback.c:2327 [inline]
 [<ffffffff81602f67>] writeback_inodes_sb+0x27/0x30 fs/fs-writeback.c:2342
 [<ffffffff8161ab23>] __sync_filesystem fs/sync.c:35 [inline]
 [<ffffffff8161ab23>] sync_filesystem+0x93/0x240 fs/sync.c:63
 [<ffffffff815795b5>] generic_shutdown_super+0x75/0x300 fs/super.c:423
 [<ffffffff81579eef>] kill_block_super+0x9f/0x120 fs/super.c:1127
 [<ffffffff8157a265>] deactivate_locked_super+0x75/0xd0 fs/super.c:310
 [<ffffffff8157ac71>] deactivate_super+0x91/0xd0 fs/super.c:341
 [<ffffffff815dcfb2>] cleanup_mnt+0xb2/0x160 fs/namespace.c:1134
 [<ffffffff815dd0e6>] __cleanup_mnt+0x16/0x20 fs/namespace.c:1141
 [<ffffffff8119833c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff8100559c>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:161
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<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
2 locks held by getty/3768:
 #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-executor0/3826:
 #0:  (&type->s_umount_key#48){++++..}, at: [<ffffffff8157ac69>] deactivate_super+0x89/0xd0 fs/super.c:340

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.111-g03c70fe #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8fb7d08 ffffffff81eb2729 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9af0 ffff8801d8fb7d40
 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: 8700 Comm: kworker/u4:9 Not tainted 4.9.111-g03c70fe #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn
c (flush-7:0)
c
task: ffff8801c4a13000 task.stack: ffff8801ac0f0000
RIP: 0010:[<ffffffff816242f1>] 
c [<ffffffff816242f1>] lookup_bh_lru fs/buffer.c:1327 [inline]
RIP: 0010:[<ffffffff816242f1>] 
c [<ffffffff816242f1>] __find_get_block+0x81/0x4c0 fs/buffer.c:1356
RSP: 0018:ffff8801ac0f75f8  EFLAGS: 00000082
RAX: 000000000001eee0 RBX: 0000000000000007 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81f1a18b RDI: ffffffff83e2da20
RBP: ffff8801ac0f7638 R08: ffff8801c4a13938 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff10038942722 R12: ffff8801a00190a8
R13: dffffc0000000000 R14: ffff8801a00191f8 R15: 0000000000000007
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcbbcc77000 CR3: 00000001bbf46000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 00000200072cba80
c 0000000000000041
c ffff8801d6192840
c 0000000000000001
c
 ffffea00072cba9c
c ffffea00072cba80
c 0000000000000200
c dffffc0000000000
c
 ffff8801ac0f76d8
c ffffffff816252b9
c ffffffff81e26534
c ffff8801d6192848
c
Call Trace:
 [<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
 [<ffffffff816045af>] wb_writeback+0x2cf/0xbd0 fs/fs-writeback.c:1760
 [<ffffffff8160dade>] wb_do_writeback fs/fs-writeback.c:1894 [inline]
 [<ffffffff8160dade>] wb_workfn+0x20e/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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c