NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
INFO: task syz-executor.1:16191 blocked for more than 140 seconds.
      Not tainted 4.14.184-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D29648 16191   6352 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x8a6/0x1d70 kernel/sched/core.c:3384
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x5f0/0x1430 kernel/locking/mutex.c:893
 fb_open+0xb7/0x400 drivers/video/fbdev/core/fbmem.c:1468
 chrdev_open+0x1fc/0x540 fs/char_dev.c:423
 do_dentry_open+0x44b/0xec0 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0xb68/0x2aa0 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x292/0x3e0 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45c1d9
RSP: 002b:00007f10dc2d8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000020880 RCX: 000000000045c1d9
RDX: 000000000082a685 RSI: 00000000200002c0 RDI: ffffffffffffff9c
RBP: 000000000078c088 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078c04c
R13: 00007ffe83bb3a1f R14: 00007f10dc2d99c0 R15: 000000000078c04c

Showing all locks held in the system:
1 lock held by khungtaskd/1057:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff8146c8d0>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
1 lock held by in:imklog/5991:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff8191e4e6>] __fdget_pos+0xa6/0xc0 fs/file.c:769
1 lock held by syz-executor.1/16191:
 #0:  (&fb_info->lock){+.+.}, at: [<ffffffff83182237>] fb_open+0xb7/0x400 drivers/video/fbdev/core/fbmem.c:1468

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

NMI backtrace for cpu 0
CPU: 0 PID: 1057 Comm: khungtaskd Not tainted 4.14.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x17f lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5e2/0xb80 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 16117 Comm: syz-executor.1 Not tainted 4.14.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88809f864640 task.stack: ffff888054688000
RIP: 0010:__sanitizer_cov_trace_pc+0x3d/0x50 kernel/kcov.c:87
RSP: 0018:ffff88805468f380 EFLAGS: 00000246
RAX: 0000000000040000 RBX: ffff8880000a0050 RCX: ffffc900060ff000
RDX: 000000000003ffff RSI: ffffffff831f9ef3 RDI: ffff88805468f438
RBP: 0000000000000050 R08: 000000000000ffff R09: ffffed104324893c
R10: ffffed104324893b R11: ffff8882192449df R12: ffff8880000a0023
R13: 0000000000000000 R14: 00000000e2a761b9 R15: 000000000000004f
FS:  00007f10dc31b700(0000) GS:ffff8880aed00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c01a228408 CR3: 00000000882ab000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 writeb arch/x86/include/asm/io.h:65 [inline]
 vga16fb_fillrect+0x943/0x1880 drivers/video/fbdev/vga16fb.c:923
 bit_clear_margins+0x2a4/0x480 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x274/0x300 drivers/video/fbdev/core/fbcon.c:1320
 fbcon_switch+0xc4e/0x1700 drivers/video/fbdev/core/fbcon.c:2302
 redraw_screen+0x332/0x760 drivers/tty/vt/vt.c:689
 fbcon_modechanged+0x552/0x800 drivers/video/fbdev/core/fbcon.c:2949
 fbcon_set_all_vcs+0x35d/0x420 drivers/video/fbdev/core/fbcon.c:2987
 fbcon_event_notify+0x72/0x1750 drivers/video/fbdev/core/fbcon.c:3305
 notifier_call_chain+0x107/0x1a0 kernel/notifier.c:93
 __blocking_notifier_call_chain kernel/notifier.c:317 [inline]
 __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 blocking_notifier_call_chain+0x79/0x90 kernel/notifier.c:325
 fb_set_var+0xaad/0xc70 drivers/video/fbdev/core/fbmem.c:1054
 do_fb_ioctl+0x3cc/0x840 drivers/video/fbdev/core/fbmem.c:1127
 fb_ioctl+0xda/0x120 drivers/video/fbdev/core/fbmem.c:1242
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45c1d9
RSP: 002b:00007f10dc31ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000000ce80 RCX: 000000000045c1d9
RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000004
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffe83bb3a1f R14: 00007f10dc31b9c0 R15: 000000000078bf0c
Code: 47 a7 7e 81 e2 00 01 1f 00 75 0b 8b 90 58 13 00 00 83 fa 01 74 01 c3 48 8b 34 24 48 8b 88 60 13 00 00 8b 80 5c 13 00 00 48 8b 11 <48> 83 c2 01 48 39 d0 76 e2 48 89 34 d1 48 89 11 c3 66 90 41 54