IPVS: stopping master sync thread 7508 ...
IPVS: stopping master sync thread 7479 ...
INFO: task syz-executor0:25063 blocked for more than 140 seconds.
      Not tainted 4.9.123-g8dd3fc2 #27
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D26296 25063      1 0x00000004
 ffff8801cc31e000 0000000000000000 ffff8801b608af40 ffff8801d9a6b000
 ffff8801db321c18 ffff8801aaf974c8 ffffffff839f0dbd ffff8801cc31e8c8
 ffffed0039863d18 ffff8801cc31e000 00fffc0000000000 ffff8801db3224e8
Call Trace:
 [<ffffffff839f23bf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839f2d43>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3586
 [<ffffffff839f71c6>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839f71c6>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff818df251>] vfat_lookup+0xd1/0x530 fs/fat/namei_vfat.c:729
 [<ffffffff815995de>] lookup_slow+0x23e/0x470 fs/namei.c:1668
 [<ffffffff815a5b66>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a7889>] link_path_walk+0x889/0x1200 fs/namei.c:2120
 [<ffffffff815a88fd>] path_openat+0x1ad/0x3590 fs/namei.c:3533
 [<ffffffff815affa7>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8157277d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff81572a5d>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff81572a5d>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a01c93>] 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: [<ffffffff81368a9c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81368a9c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.?..}, at: [<ffffffff81428308>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3776:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839ffe62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff821253c2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor0/25063:
 #0:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815994e1>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815994e1>] lookup_slow+0x141/0x470 fs/namei.c:1645
 #1:  (&sbi->s_lock){+.+.+.}, at: [<ffffffff818df251>] vfat_lookup+0xd1/0x530 fs/fat/namei_vfat.c:729
1 lock held by syz-executor0/10727:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815dc88c>] __fdget_pos+0xac/0xd0 fs/file.c:781

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.123-g8dd3fc2 #27
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d853fd08 ffffffff81eb9689 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9fa0 ffff8801d853fd40
 ffffffff81ec49c7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb9689>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb9689>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ec49c7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ec495a>] 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
 [<ffffffff81369034>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81369034>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81369034>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81369034>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119f3cd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff83a01e5c>] 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: 10674 Comm: syz-executor0 Not tainted 4.9.123-g8dd3fc2 #27
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88019ab9c800 task.stack: ffff880187de8000
RIP: 0010:[<ffffffff812384e5>] 
c [<ffffffff812384e5>] __lock_acquire+0x75/0x4070 kernel/locking/lockdep.c:3204
RSP: 0018:ffff880187def5b0  EFLAGS: 00000086
RAX: ffffed0030fbdeca RBX: 0000000000000246 RCX: 0000000000000002
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffffff846df4a0
RBP: ffff880187def758 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88019ab9c800
R13: 0000000000000000 R14: ffffffff846df4a0 R15: 0000000000000000
FS:  00007fa33de27700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000164e000 CR3: 000000018eab1000 CR4: 00000000001606f0
DR0: 0000000020000080 DR1: 0000000020000080 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff81238470
c ffff8801db321c00
c ffff88019c473000
c ffff880187def5d8
c
 ffff8801db321c00
c ffff880187def5f0
c ffffffff83a01918
c ffff8801db321c00
c
 ffff880187def648
c 0000000000000002
c ffff88019ab9d0c8
c ffffed0033573a18
c
Call Trace:
 [<ffffffff8123cf50>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff8143b1aa>] rcu_lock_acquire include/linux/rcupdate.h:493 [inline]
 [<ffffffff8143b1aa>] rcu_read_lock include/linux/rcupdate.h:875 [inline]
 [<ffffffff8143b1aa>] find_get_entry+0x4a/0x540 mm/filemap.c:1090
 [<ffffffff8143c5db>] pagecache_get_page+0x4b/0x720 mm/filemap.c:1201
 [<ffffffff81629c49>] find_or_create_page include/linux/pagemap.h:309 [inline]
 [<ffffffff81629c49>] grow_dev_page fs/buffer.c:1005 [inline]
 [<ffffffff81629c49>] grow_buffers fs/buffer.c:1078 [inline]
 [<ffffffff81629c49>] __getblk_slow fs/buffer.c:1105 [inline]
 [<ffffffff81629c49>] __getblk_gfp+0x249/0x710 fs/buffer.c:1386
 [<ffffffff8162d52d>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818bc718>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818bc718>] fat__get_entry+0x4c8/0x8f0 fs/fat/dir.c:100
 [<ffffffff818c578c>] fat_get_entry fs/fat/dir.c:128 [inline]
 [<ffffffff818c578c>] __fat_readdir+0x36c/0x1840 fs/fat/dir.c:589
 [<ffffffff818c6ca1>] fat_readdir+0x41/0x50 fs/fat/dir.c:703
 [<ffffffff815b877c>] iterate_dir+0x1ac/0x600 fs/readdir.c:50
 [<ffffffff815b97bc>] SYSC_getdents fs/readdir.c:230 [inline]
 [<ffffffff815b97bc>] SyS_getdents+0x13c/0x2a0 fs/readdir.c:211
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a01c93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c