INFO: task syz-executor.0:6314 blocked for more than 140 seconds. Not tainted 4.19.126-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D29152 6314 11996 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_timeout+0x8f3/0xed0 kernel/time/timer.c:1782 __down_common kernel/locking/semaphore.c:221 [inline] __down+0x192/0x2b0 kernel/locking/semaphore.c:238 down+0x57/0x80 kernel/locking/semaphore.c:62 console_lock+0x25/0x80 kernel/printk/printk.c:2244 do_con_write.part.0+0xa8/0x1db0 drivers/tty/vt/vt.c:2576 do_con_write drivers/tty/vt/vt.c:2571 [inline] con_write+0x41/0xe0 drivers/tty/vt/vt.c:3138 process_output_block drivers/tty/n_tty.c:593 [inline] n_tty_write+0x3ee/0x1080 drivers/tty/n_tty.c:2331 do_tty_write drivers/tty/tty_io.c:960 [inline] tty_write+0x455/0x790 drivers/tty/tty_io.c:1044 __vfs_write+0xf7/0x760 fs/read_write.c:485 vfs_write+0x1f3/0x540 fs/read_write.c:549 ksys_write+0x12b/0x2a0 fs/read_write.c:599 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45ca69 Code: 48 c7 44 24 10 00 00 00 00 48 8b 44 24 68 48 89 44 24 18 48 8b 44 24 70 48 89 44 24 20 48 8b 44 24 78 48 89 44 24 28 48 89 4c <24> 30 0f 57 c0 0f 11 44 24 38 48 c7 44 24 48 00 00 00 00 e8 0f d4 RSP: 002b:00007f903485bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000050c680 RCX: 000000000045ca69 RDX: 0000000000001006 RSI: 0000000020001440 RDI: 0000000000000004 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000ce0 R14: 00000000004cf306 R15: 00007f903485c6d4 Showing all locks held in the system: 1 lock held by khungtaskd/1078: #0: 000000007d1676e2 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440 1 lock held by in:imklog/6126: #0: 00000000b473d325 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:767 2 locks held by agetty/6348: #0: 000000005a6423c1 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272 #1: 00000000aab1d15e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x217/0x1a50 drivers/tty/n_tty.c:2154 2 locks held by agetty/6349: #0: 0000000049db6b4b (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272 #1: 000000007b562005 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x217/0x1a50 drivers/tty/n_tty.c:2154 1 lock held by syz-executor.4/6311: 4 locks held by syz-executor.0/6314: #0: 0000000049db6b4b (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272 #1: 0000000031bd40e2 (&tty->atomic_write_lock){+.+.}, at: tty_write_lock+0x1e/0x80 drivers/tty/tty_io.c:886 #2: 00000000376c7745 (&tty->termios_rwsem){++++}, at: n_tty_write+0x1b2/0x1080 drivers/tty/n_tty.c:2314 #3: 0000000037cc0d62 (&ldata->output_lock){+.+.}, at: process_output_block drivers/tty/n_tty.c:548 [inline] #3: 0000000037cc0d62 (&ldata->output_lock){+.+.}, at: n_tty_write+0x505/0x1080 drivers/tty/n_tty.c:2331 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1078 Comm: khungtaskd Not tainted 4.19.126-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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 6311 Comm: syz-executor.4 Not tainted 4.19.126-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__sanitizer_cov_trace_pc+0x37/0x50 kernel/kcov.c:106 Code: 65 8b 15 ec 62 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 00 00 48 8b 11 <48> 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 c3 0f 1f 84 00 00 RSP: 0018:ffff88804938f680 EFLAGS: 00000246 RAX: 0000000000040000 RBX: 0000000000000000 RCX: ffffc9000e4f9000 RDX: 000000000003ffff RSI: ffffffff83770c7c RDI: 0000000000000005 RBP: ffff8880000a00c0 R08: ffff8880426fa540 R09: 0000000000000040 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000050 R13: ffff8880000a0000 R14: 0000000000000000 R15: 0000000000000038 FS: 00007f927a602700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000c008cb9578 CR3: 0000000042675000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: bitfill_aligned drivers/video/fbdev/core/cfbfillrect.c:64 [inline] bitfill_aligned+0xfc/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_do_set_font+0x71d/0xa30 drivers/video/fbdev/core/fbcon.c:2585 fbcon_set_font+0x733/0x870 drivers/video/fbdev/core/fbcon.c:2677 con_font_set drivers/tty/vt/vt.c:4529 [inline] con_font_op+0xd3e/0x1130 drivers/tty/vt/vt.c:4594 vt_ioctl+0xcd0/0x2500 drivers/tty/vt/vt_ioctl.c:928 tty_ioctl+0x7a5/0x1420 drivers/tty/tty_io.c:2669 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: 0033:0x45ca69 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:00007f927a601c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004e96c0 RCX: 000000000045ca69 RDX: 0000000020000240 RSI: 0000000000004b61 RDI: 0000000000000003 RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000421 R14: 00000000004c6e58 R15: 00007f927a6026d4