NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
INFO: task syz-executor.4:2695 blocked for more than 140 seconds.
      Not tainted 4.19.125-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D29224  2695   6851 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2826 [inline]
 __schedule+0x8a2/0x1fc0 kernel/sched/core.c:3515
 schedule+0x8d/0x1b0 kernel/sched/core.c:3559
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3617
 __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
 __mutex_lock+0x5b8/0x1300 kernel/locking/mutex.c:1072
 fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1457
 chrdev_open+0x219/0x5c0 fs/char_dev.c:423
 do_dentry_open+0x4a8/0x1160 fs/open.c:796
 do_last fs/namei.c:3421 [inline]
 path_openat+0xe06/0x2eb0 fs/namei.c:3537
 do_filp_open+0x1a1/0x280 fs/namei.c:3567
 do_sys_open+0x3aa/0x510 fs/open.c:1085
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45ca29
Code: 8b 44 24 10 48 85 c0 74 09 48 8b 2c 24 48 83 c4 08 c3 e8 fa 96 fa ff 0f 0b 48 8d 7c 24 10 48 39 3b 75 dc 48 89 23 eb d7 cc cc <cc> cc cc cc cc cc cc 64 48 8b 0c 25 f8 ff ff ff 48 3b 61 10 76 79
RSP: 002b:00007f71bf545c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00000000004f7640 RCX: 000000000045ca29
RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c
RBP: 000000000078c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000007a0 R14: 00000000004ca744 R15: 00007f71bf5466d4

Showing all locks held in the system:
1 lock held by khungtaskd/1079:
 #0: 0000000040f07e1f (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by in:imklog/6127:
 #0: 000000004093d4ba (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:767
3 locks held by syz-executor.4/2637:
1 lock held by syz-executor.4/2695:
 #0: 000000004ff50aaa (&fb_info->lock){+.+.}, at: fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1457

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

NMI backtrace for cpu 1
CPU: 1 PID: 1079 Comm: khungtaskd Not tainted 4.19.125-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+0x1fc/0x2fe lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
 watchdog+0x962/0xe40 kernel/hung_task.c:287
 kthread+0x30b/0x410 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2637 Comm: syz-executor.4 Not tainted 4.19.125-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__read_once_size include/linux/compiler.h:193 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:69 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x1c/0x50 kernel/kcov.c:101
Code: b6 93 06 0a 00 00 00 00 e9 24 ec ff ff 90 48 8b 34 24 65 48 8b 04 25 40 ee 01 00 65 8b 15 2c 64 9a 7e 81 e2 00 01 1f 00 75 2b <8b> 90 d8 12 00 00 83 fa 02 75 20 48 8b 88 e0 12 00 00 8b 80 dc 12
RSP: 0018:ffff8880947ff198 EFLAGS: 00000246
RAX: ffff888042c44580 RBX: 0000000000000000 RCX: ffffffff83774925
RDX: 0000000000000000 RSI: ffffffff83774933 RDI: 0000000000000005
RBP: 0000000000000040 R08: ffff888042c44580 R09: 0000000000000040
R10: ffffed1014acd7c3 R11: ffff8880a566be1f R12: 0000000000001400
R13: ffff8880000a0000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f71bf588700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f77160dbc60 CR3: 000000008c6dc000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 bitfill_aligned drivers/video/fbdev/core/cfbfillrect.c:62 [inline]
 bitfill_aligned+0xd3/0x200 drivers/video/fbdev/core/cfbfillrect.c:35
 cfb_fillrect+0x418/0x7a0 drivers/video/fbdev/core/cfbfillrect.c:327
 vga16fb_fillrect+0x68f/0x1960 drivers/video/fbdev/vga16fb.c:951
 bit_clear_margins+0x2d5/0x4a0 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x2c7/0x350 drivers/video/fbdev/core/fbcon.c:1342
 fbcon_switch+0xd9f/0x18f0 drivers/video/fbdev/core/fbcon.c:2324
 redraw_screen+0x37d/0x870 drivers/tty/vt/vt.c:1015
 fbcon_modechanged+0x5a0/0x870 drivers/video/fbdev/core/fbcon.c:2972
 fbcon_set_all_vcs+0x3b5/0x470 drivers/video/fbdev/core/fbcon.c:3010
 fbcon_event_notify+0x95/0x1d60 drivers/video/fbdev/core/fbcon.c:3350
 notifier_call_chain+0xc0/0x230 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+0x85/0xa0 kernel/notifier.c:325
 fb_set_var+0xc39/0xe00 drivers/video/fbdev/core/fbmem.c:1042
 do_fb_ioctl+0x450/0x9c0 drivers/video/fbdev/core/fbmem.c:1115
 fb_ioctl+0xda/0x120 drivers/video/fbdev/core/fbmem.c:1230
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcda/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45ca29
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f71bf587c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e4ac0 RCX: 000000000045ca29
RDX: 0000000020000340 RSI: 0000000000004601 RDI: 0000000000000008
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000002f2 R14: 00000000004c56c8 R15: 00007f71bf5886d4