INFO: task syz-executor.2:18641 blocked for more than 143 seconds. Not tainted 5.8.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28632 18641 6927 0x00004004 Call Trace: context_switch kernel/sched/core.c:3778 [inline] __schedule+0x8e5/0x21e0 kernel/sched/core.c:4527 schedule+0xd0/0x2a0 kernel/sched/core.c:4602 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4661 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x3e2/0x10e0 kernel/locking/mutex.c:1103 lock_fb_info include/linux/fb.h:636 [inline] fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1414 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x4b9/0x11b0 fs/open.c:817 do_open fs/namei.c:3249 [inline] path_openat+0x1b9a/0x2730 fs/namei.c:3366 do_filp_open+0x17e/0x3c0 fs/namei.c:3393 do_sys_openat2+0x16d/0x420 fs/open.c:1168 do_sys_open fs/open.c:1184 [inline] __do_sys_openat fs/open.c:1200 [inline] __se_sys_openat fs/open.c:1195 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1195 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d249 Code: Bad RIP value. RSP: 002b:00007f12f5f39c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000021940 RCX: 000000000045d249 RDX: 0000000000000000 RSI: 0000000020000180 RDI: ffffffffffffff9c RBP: 000000000118d028 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cfec R13: 00007ffecc1b1b6f R14: 00007f12f5f3a9c0 R15: 000000000118cfec Showing all locks held in the system: 1 lock held by khungtaskd/1167: #0: ffffffff89bd6380 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5825 1 lock held by in:imklog/6523: #0: ffff88809299d430 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930 2 locks held by agetty/6761: #0: ffff8880a8bc6098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900010202e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156 2 locks held by agetty/6762: #0: ffff888091c95098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc90000ff42e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.2/18557: 1 lock held by syz-executor.2/18641: #0: ffff8880a2e1b078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:636 [inline] #0: ffff8880a2e1b078 (&fb_info->lock){+.+.}-{3:3}, at: fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1414 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1167 Comm: khungtaskd Not tainted 5.8.0-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:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 18557 Comm: syz-executor.2 Not tainted 5.8.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__sanitizer_cov_trace_pc+0x55/0x60 kernel/kcov.c:207 Code: 82 e8 13 00 00 83 f8 02 75 20 48 8b 8a f0 13 00 00 8b 92 ec 13 00 00 48 8b 01 48 83 c0 01 48 39 c2 76 07 48 89 34 c1 48 89 01 66 2e 0f 1f 84 00 00 00 00 00 41 55 41 54 49 89 fc 55 48 bd eb RSP: 0018:ffffc9000303f848 EFLAGS: 00000246 RAX: 0000000000040000 RBX: 0000000000000050 RCX: ffffc900101ae000 RDX: 0000000000040000 RSI: ffffffff83c9a0e0 RDI: 0000000000000004 RBP: 0000000000000024 R08: 0000000000000001 R09: ffff8880a2d0d09f R10: 0000000000000050 R11: 0000000000000000 R12: ffff8880000a0024 R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000f0d4071d FS: 00007f12f5f5b700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055e8191e02a0 CR3: 000000009eb69000 CR4: 00000000001506e0 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+0x2d5/0x4b0 drivers/video/fbdev/core/bitblit.c:232 fbcon_clear_margins+0x1d5/0x230 drivers/video/fbdev/core/fbcon.c:1381 fbcon_switch+0xb6f/0x16c0 drivers/video/fbdev/core/fbcon.c:2363 redraw_screen+0x2af/0x770 drivers/tty/vt/vt.c:1020 fbcon_modechanged+0x575/0x710 drivers/video/fbdev/core/fbcon.c:3001 fbcon_update_vcs+0x3a/0x50 drivers/video/fbdev/core/fbcon.c:3048 do_fb_ioctl+0x62e/0x690 drivers/video/fbdev/core/fbmem.c:1106 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1181 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d249 Code: 5d b4 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 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f12f5f5ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000000000000d580 RCX: 000000000045d249 RDX: 0000000020000200 RSI: 0000000000004601 RDI: 0000000000000004 RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffecc1b1b6f R14: 00007f12f5f5b9c0 R15: 000000000118cf4c