INFO: task syz-executor.3:11042 blocked for more than 143 seconds.
      Not tainted 5.8.0-rc6-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D28752 11042   7125 0x00004004
Call Trace:
 context_switch kernel/sched/core.c:3458 [inline]
 __schedule+0x91f/0x2250 kernel/sched/core.c:4215
 schedule+0xd0/0x2a0 kernel/sched/core.c:4290
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4349
 __mutex_lock_common kernel/locking/mutex.c:1033 [inline]
 __mutex_lock+0x3e2/0x10d0 kernel/locking/mutex.c:1103
 lock_fb_info include/linux/fb.h:637 [inline]
 fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1418
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x501/0x1290 fs/open.c:828
 do_open fs/namei.c:3243 [inline]
 path_openat+0x1bb9/0x2750 fs/namei.c:3360
 do_filp_open+0x17e/0x3c0 fs/namei.c:3387
 do_sys_openat2+0x16f/0x3b0 fs/open.c:1179
 do_sys_open fs/open.c:1195 [inline]
 __do_sys_openat fs/open.c:1209 [inline]
 __se_sys_openat fs/open.c:1204 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1204
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c1f9
Code: Bad RIP value.
RSP: 002b:00007f95a439dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000020ec0 RCX: 000000000045c1f9
RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c
RBP: 000000000078bfe8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bfac
R13: 0000000000c9fb6f R14: 00007f95a439e9c0 R15: 000000000078bfac

Showing all locks held in the system:
1 lock held by khungtaskd/1151:
 #0: ffffffff89bc11c0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5779
1 lock held by in:imklog/6715:
 #0: ffff88809692baf0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826
2 locks held by syz-executor.3/10994:
1 lock held by syz-executor.3/11042:
 #0: ffff88821881f078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline]
 #0: ffff88821881f078 (&fb_info->lock){+.+.}-{3:3}, at: fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1418

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

NMI backtrace for cpu 1
CPU: 1 PID: 1151 Comm: khungtaskd Not tainted 5.8.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline]
 watchdog+0xd7d/0x1000 kernel/hung_task.c:295
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10994 Comm: syz-executor.3 Not tainted 5.8.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__sanitizer_cov_trace_pc+0x3c/0x60 kernel/kcov.c:203
Code: 01 ff 00 48 8b 34 24 74 0f f6 c4 01 74 35 8b 82 04 14 00 00 85 c0 74 2b 8b 82 e0 13 00 00 83 f8 02 75 20 48 8b 8a e8 13 00 00 <8b> 92 e4 13 00 00 48 8b 01 48 83 c0 01 48 39 c2 76 07 48 89 34 c1
RSP: 0018:ffffc900081675a8 EFLAGS: 00000246
RAX: 0000000000000002 RBX: 0000000000000050 RCX: ffffc9000f331000
RDX: ffff88809017c1c0 RSI: ffffffff83c66fd0 RDI: 0000000000000004
RBP: 0000000000000048 R08: 0000000000000001 R09: ffff88821881c2df
R10: 0000000000000050 R11: 0000000000000000 R12: ffff8880000a0048
R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000f21c2db9
FS:  00007f95a43bf700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff9f0772d7f CR3: 00000000a2420000 CR4: 00000000001406f0
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+0x9c0/0x193b drivers/video/fbdev/vga16fb.c:923
 bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x1d5/0x230 drivers/video/fbdev/core/fbcon.c:1381
 fbcon_switch+0xb6e/0x16c0 drivers/video/fbdev/core/fbcon.c:2363
 redraw_screen+0x2ae/0x770 drivers/tty/vt/vt.c:1015
 fbcon_modechanged+0x575/0x710 drivers/video/fbdev/core/fbcon.c:3001
 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3048
 fb_set_var+0xae8/0xd60 drivers/video/fbdev/core/fbmem.c:1056
 do_fb_ioctl+0x33f/0x6c0 drivers/video/fbdev/core/fbmem.c:1109
 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1185
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c1f9
Code: Bad RIP value.
RSP: 002b:00007f95a43bec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000000d400 RCX: 000000000045c1f9
RDX: 00000000200001c0 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 0000000000c9fb6f R14: 00007f95a43bf9c0 R15: 000000000078bf0c