9pnet_virtio: no channels available for device (null)
9pnet: Insufficient options for proto=fd
INFO: task syz-executor6:7066 blocked for more than 140 seconds.
      Not tainted 4.9.120-gf85543b #24
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor6   D26760  7066      1 0x00000004
 ffff8801cfc0b000 0000000000000000 ffff8801d3652f40 ffff8801d9a6b000
 ffff8801db321c18 ffff8801a89474b8 ffffffff839eedcd dffffc0000000000
 ffff8801bb62ed70 ffff8801a8947478 00ff8801cfc0b8c0 ffff8801db3224e8
Call Trace:
 [<ffffffff839f03cf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff815cab72>] d_wait_lookup fs/dcache.c:2454 [inline]
 [<ffffffff815cab72>] d_alloc_parallel+0xeb2/0x17c0 fs/dcache.c:2536
 [<ffffffff81597cbc>] lookup_slow+0x19c/0x470 fs/namei.c:1650
 [<ffffffff815a42e6>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a6009>] link_path_walk+0x889/0x1200 fs/namei.c:2120
 [<ffffffff815a707d>] path_openat+0x1ad/0x3590 fs/namei.c:3533
 [<ffffffff815ae727>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff81570efd>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff815711dd>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff815711dd>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839ffcd3>] 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: [<ffffffff813684dc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813684dc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81427d48>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3780:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839fde72>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff82123d42>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor6/7066:
 #0:  (&sb->s_type->i_mutex_key#16){++++++}, at: [<ffffffff81597c61>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#16){++++++}, at: [<ffffffff81597c61>] lookup_slow+0x141/0x470 fs/namei.c:1645

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.120-gf85543b #24
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d855fd08 ffffffff81eb8049 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9fa0 ffff8801d855fd40
 ffffffff81ec3357 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb8049>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb8049>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ec3357>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ec32ea>] 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
 [<ffffffff81368a74>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81368a74>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81368a74>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81368a74>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ee0d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839ffe9c>] 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: 29633 Comm: syz-executor6 Not tainted 4.9.120-gf85543b #24
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801ce279800 task.stack: ffff8801d0328000
RIP: 0010:[<ffffffff81f1fab3>] 
c [<ffffffff81f1fab3>] arch_local_save_flags arch/x86/include/asm/paravirt.h:763 [inline]
RIP: 0010:[<ffffffff81f1fab3>] 
c [<ffffffff81f1fab3>] check_preemption_disabled+0x53/0x170 lib/smp_processor_id.c:18
RSP: 0018:ffff8801d032f010  EFLAGS: 00000046
RAX: 0000000000000046 RBX: 0000000000000001 RCX: ffffc90010dd6000
RDX: 0000000000040000 RSI: ffffffff81f1fab1 RDI: ffffffff83e2e820
RBP: ffff8801d032f040 R08: ffff8801ce27a138 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff10039c4f422 R12: ffffffff83e2e820
R13: ffffffff83ccebe0 R14: ffff8801bb4ac150 R15: 000000000000000f
FS:  00007f54e162a700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f710db2e000 CR3: 00000001d3d2f000 CR4: 00000000001606f0
Stack:
 ffffffff843bd709
c ffffffff83ccebe0
c ffff8801bb4ac150
c dffffc0000000000
c
 ffff8801bb4ac150
c 000000000000000f
c ffff8801d032f058
c ffffffff81f1fc0c
c
 000000000000000f
c ffff8801d032f0a8
c ffffffff81627335
c 00000200087db540
c
Call Trace:
 [<ffffffff81f1fc0c>] __this_cpu_preempt_check+0x1c/0x20 lib/smp_processor_id.c:62
 [<ffffffff81627335>] lookup_bh_lru fs/buffer.c:1327 [inline]
 [<ffffffff81627335>] __find_get_block+0x75/0x4c0 fs/buffer.c:1356
 [<ffffffff81628309>] __getblk_slow fs/buffer.c:1101 [inline]
 [<ffffffff81628309>] __getblk_gfp+0x189/0x710 fs/buffer.c:1386
 [<ffffffff8162bcad>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818bad48>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818bad48>] fat__get_entry+0x4c8/0x8f0 fs/fat/dir.c:100
 [<ffffffff818c2b47>] fat_get_entry fs/fat/dir.c:128 [inline]
 [<ffffffff818c2b47>] fat_search_long+0x277/0x1180 fs/fat/dir.c:477
 [<ffffffff818dd0b4>] vfat_find+0x134/0x180 fs/fat/namei_vfat.c:708
 [<ffffffff818dd891>] vfat_lookup+0xe1/0x530 fs/fat/namei_vfat.c:731
 [<ffffffff81597d5e>] lookup_slow+0x23e/0x470 fs/namei.c:1668
 [<ffffffff815a42e6>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a6009>] link_path_walk+0x889/0x1200 fs/namei.c:2120
 [<ffffffff815a707d>] path_openat+0x1ad/0x3590 fs/namei.c:3533
 [<ffffffff815ae727>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff81570efd>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff815711dd>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff815711dd>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839ffcd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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