INFO: task agetty:6546 blocked for more than 143 seconds. Not tainted 5.9.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:agetty state:D stack:27648 pid: 6546 ppid: 1 flags:0x00000000 Call Trace: context_switch kernel/sched/core.c:3778 [inline] __schedule+0xea9/0x2230 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 commit_echoes+0x4c/0x210 drivers/tty/n_tty.c:778 n_tty_receive_char_fast drivers/tty/n_tty.c:1449 [inline] n_tty_receive_buf_fast drivers/tty/n_tty.c:1609 [inline] __receive_buf drivers/tty/n_tty.c:1644 [inline] n_tty_receive_buf_common+0x203f/0x2bc0 drivers/tty/n_tty.c:1742 tiocsti drivers/tty/tty_io.c:2196 [inline] tty_ioctl+0xf2e/0x15f0 drivers/tty/tty_io.c:2572 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: 0033:0x7fe86426a017 Code: Bad RIP value. RSP: 002b:00007fff33842848 EFLAGS: 00000202 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fff338429c1 RCX: 00007fe86426a017 RDX: 00007fff338429c0 RSI: 0000000000005412 RDI: 0000000000000000 RBP: 00007fff338429c5 R08: ffffffffffffff98 R09: 00007fff338428c0 R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff33842864 R13: 00007fff338429c0 R14: 00007fff338428c0 R15: 0000000000000000 Showing all locks held in the system: 1 lock held by khungtaskd/1167: #0: ffffffff89bd6a40 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5829 1 lock held by in:imklog/6529: #0: ffff8880a802f430 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930 3 locks held by agetty/6546: #0: ffff8880a96af098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffff8880a96af2e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_receive_buf_common+0x89/0x2bc0 drivers/tty/n_tty.c:1705 #2: ffffc90000f01378 (&ldata->output_lock){+.+.}-{3:3}, at: commit_echoes+0x4c/0x210 drivers/tty/n_tty.c:778 5 locks held by syz-executor.5/13224: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1167 Comm: khungtaskd Not tainted 5.9.0-rc3-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+0x198/0x1fd 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: 13224 Comm: syz-executor.5 Not tainted 5.9.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:write_comp_data+0x0/0x80 kernel/kcov.c:212 Code: e8 ff ff cc cc cc cc cc cc cc 65 48 8b 04 25 c0 fe 01 00 48 8b 80 18 14 00 00 c3 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 <49> 89 f2 65 8b 05 36 b8 8d 7e 65 48 8b 34 25 c0 fe 01 00 a9 00 01 RSP: 0018:ffffc90015d9f748 EFLAGS: 00000286 RAX: 0000000000040000 RBX: 0000000000000050 RCX: ffffffff83cadd14 RDX: 000000000000003f RSI: 0000000000000050 RDI: 0000000000000004 RBP: 000000000000003f R08: 0000000000000010 R09: 0000000000000280 R10: 0000000000000050 R11: 0000000000000000 R12: ffff8880000a003f R13: ffff8880000a0000 R14: 0000000000000000 R15: 00000000efd464bd FS: 00007f7c7210b700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fea5bbbb000 CR3: 000000008547a000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: vga16fb_fillrect+0x9d4/0x193b drivers/video/fbdev/vga16fb.c:922 bit_clear+0x386/0x4d0 drivers/video/fbdev/core/bitblit.c:74 fbcon_clear+0x519/0x5a0 drivers/video/fbdev/core/fbcon.c:1351 fbcon_scroll+0x1e20/0x3600 drivers/video/fbdev/core/fbcon.c:1980 con_scroll+0x5b9/0x6d0 drivers/tty/vt/vt.c:629 lf+0x26b/0x2c0 drivers/tty/vt/vt.c:1490 vc_con_write_normal drivers/tty/vt/vt.c:2806 [inline] do_con_write+0xedd/0x1d70 drivers/tty/vt/vt.c:2910 con_write+0x22/0xb0 drivers/tty/vt/vt.c:3250 process_output_block drivers/tty/n_tty.c:595 [inline] n_tty_write+0x3ce/0xf80 drivers/tty/n_tty.c:2333 do_tty_write drivers/tty/tty_io.c:962 [inline] tty_write+0x4d9/0x870 drivers/tty/tty_io.c:1046 vfs_write+0x2b0/0x730 fs/read_write.c:576 ksys_write+0x12d/0x250 fs/read_write.c:631 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 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:00007f7c7210ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000038900 RCX: 000000000045d5b9 RDX: 0000000000001006 RSI: 0000000020001440 RDI: 0000000000000007 RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 000000000169fb6f R14: 00007f7c7210b9c0 R15: 000000000118cf4c