INFO: task syz-executor443:8525 blocked for more than 140 seconds. Not tainted 4.19.158-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor443 D28648 8525 8094 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x887/0x2040 kernel/sched/core.c:3517 schedule+0x8d/0x1b0 kernel/sched/core.c:3561 schedule_timeout+0x92d/0xfe0 kernel/time/timer.c:1794 __down_common kernel/locking/semaphore.c:221 [inline] __down+0x183/0x2a0 kernel/locking/semaphore.c:238 down+0x57/0x80 kernel/locking/semaphore.c:62 console_lock+0x25/0x80 kernel/printk/printk.c:2275 do_fb_ioctl+0x33e/0xb50 drivers/video/fbdev/core/fbmem.c:1109 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1230 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0xcdb/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: 0033:0x445189 Code: Bad RIP value. RSP: 002b:00007ffe06dac238 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000020000080 RCX: 0000000000445189 RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000003 RBP: 0000000000087630 R08: 00000000004002e0 R09: 00000000004002e0 R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000402350 R13: 00000000004023e0 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 7 locks held by kworker/u4:2/101: 1 lock held by khungtaskd/1567: #0: 00000000c59e5605 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440 1 lock held by in:imklog/7789: #0: 00000000e998af56 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767 2 locks held by agetty/7802: #0: 0000000086fa765f (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272 #1: 0000000035130b29 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x217/0x1950 drivers/tty/n_tty.c:2154 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1567 Comm: khungtaskd Not tainted 4.19.158-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+0x991/0xe60 kernel/hung_task.c:287 kthread+0x33f/0x460 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 101 Comm: kworker/u4:2 Not tainted 4.19.158-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound flush_to_ldisc RIP: 0010:vga16fb_fillrect+0x9d4/0x1940 drivers/video/fbdev/vga16fb.c:922 Code: ff 89 de 31 ed e8 4c 6e bc fd 85 db 4d 89 ec 74 22 e8 d0 6c bc fd 45 88 34 24 83 c5 01 89 df 49 83 c4 01 89 ee e8 ac 6d bc fd <39> eb 75 e3 89 d8 49 01 c5 e8 ae 6c bc fd 31 ff 44 89 fe 4c 03 2c RSP: 0018:ffff8880b53c74d0 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000050 RCX: ffffffff83a86344 RDX: 000000000000003c RSI: ffff8880b53bc3c0 RDI: 0000000000000004 RBP: 000000000000003c R08: 0000000000000010 R09: 0000000000000050 R10: 0000000000000004 R11: 0000000000000000 R12: ffff8880000a003c R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000e8bc1d07 FS: 0000000000000000(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000006d0080 CR3: 00000000a46c2000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: bit_clear+0x382/0x4d0 drivers/video/fbdev/core/bitblit.c:74 fbcon_clear+0x5d6/0x690 drivers/video/fbdev/core/fbcon.c:1258 fbcon_scroll+0x42e/0x3440 drivers/video/fbdev/core/fbcon.c:1756 con_scroll+0x5f8/0x720 drivers/tty/vt/vt.c:637 lf+0x262/0x2b0 drivers/tty/vt/vt.c:1491 do_con_write+0x133e/0x1d90 drivers/tty/vt/vt.c:2768 con_put_char+0x96/0xe0 drivers/tty/vt/vt.c:3155 tty_put_char+0xb7/0x150 drivers/tty/tty_io.c:2887 do_output_char+0x155/0x850 drivers/tty/n_tty.c:486 __process_echoes+0x38e/0x9f0 drivers/tty/n_tty.c:737 flush_echoes drivers/tty/n_tty.c:827 [inline] __receive_buf drivers/tty/n_tty.c:1646 [inline] n_tty_receive_buf_common+0xc0c/0x2a90 drivers/tty/n_tty.c:1740 tty_ldisc_receive_buf+0xa9/0x190 drivers/tty/tty_buffer.c:456 tty_port_default_receive_buf+0x78/0xa0 drivers/tty/tty_port.c:38 receive_buf drivers/tty/tty_buffer.c:476 [inline] flush_to_ldisc+0x21f/0x390 drivers/tty/tty_buffer.c:528 process_one_work+0x864/0x1570 kernel/workqueue.c:2155 worker_thread+0x64c/0x1130 kernel/workqueue.c:2298 kthread+0x33f/0x460 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415