syzbot

 sign-in | mailing list | source | docs
🐞 Open [712]
🐞 Fixed [297]
🐞 Invalid [838]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: task hung in vt_ioctl

Status: auto-closed as invalid on 2020/09/24 20:12
Reported-by: syzbot+6d3ed27bd81301cc5b45@syzkaller.appspotmail.com
First crash: 2240d, last: 2240d
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in vt_ioctl (7) prio:high kernel 1 2 92d 95d 0/29 auto-obsoleted due to no activity on 2026/07/14 12:03
linux-6.6 INFO: task hung in vt_ioctl 1 1 255d 255d 0/2 auto-obsoleted due to no activity on 2026/02/10 14:54
upstream INFO: task hung in vt_ioctl (4) serial 1 1 1030d 1030d 0/29 auto-obsoleted due to no activity on 2023/12/19 05:20
upstream INFO: task hung in vt_ioctl (6) kernel 1 1 332d 332d 0/29 auto-obsoleted due to no activity on 2025/11/16 03:48
upstream INFO: task hung in vt_ioctl (3) serial 1 1 1210d 1210d 0/29 auto-obsoleted due to no activity on 2023/06/22 09:16
upstream INFO: task hung in vt_ioctl serial 1 1 2334d 2334d 0/29 auto-closed as invalid on 2020/05/23 20:53
upstream INFO: task hung in vt_ioctl (2) serial 1 2 2204d 2242d 0/29 auto-closed as invalid on 2020/10/01 08:58
upstream INFO: task hung in vt_ioctl (5) kernel 1 1 494d 494d 0/29 auto-obsoleted due to no activity on 2025/06/06 19:57

Sample crash report:
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
NOHZ: local_softirq_pending 08
INFO: task syz-executor.0:17895 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.0  D27888 17895   6462 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
 vt_ioctl+0x105c/0x2500 drivers/tty/vt/vt_ioctl.c:843
 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: 0033:0x45ca29
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:00007fd688e67c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e6cc0 RCX: 000000000045ca29
RDX: 0000000020000240 RSI: 0000000000005609 RDI: 0000000000000006
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000037a R14: 00000000004c60c9 R15: 00007fd688e686d4

Showing all locks held in the system:
1 lock held by khungtaskd/1079:
 #0: 000000009dad672f (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by in:imklog/6128:
 #0: 00000000d7e3808b (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:767
1 lock held by syz-executor.0/17885:

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

NMI backtrace for cpu 0
CPU: 0 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 17885 Comm: syz-executor.0 Not tainted 4.19.125-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__sanitizer_cov_trace_pc+0x22/0x50 kernel/kcov.c:101
Code: 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 00 00 48 8b 11 48
RSP: 0018:ffff8880466af4c8 EFLAGS: 00000246
RAX: ffff8880935ca340 RBX: 0000000000000000 RCX: ffffffff83774994
RDX: 0000000000000002 RSI: ffffffff8377495c RDI: 0000000000000005
RBP: ffff8880000a0200 R08: ffff8880935ca340 R09: 0000000000000040
R10: ffffed1014aa41a3 R11: ffff8880a5520d1f R12: 0000000000000050
R13: ffff8880000a0000 R14: 0000000000000000 R15: 0000000000000010
FS:  00007fd688e89700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b2361ba920 CR3: 000000009f2e8000 CR4: 00000000001426e0
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_switch+0xd9f/0x18f0 drivers/video/fbdev/core/fbcon.c:2324
 redraw_screen+0x37d/0x870 drivers/tty/vt/vt.c:1015
 vc_do_resize+0x108e/0x1380 drivers/tty/vt/vt.c:1317
 vt_ioctl+0x10c1/0x2500 drivers/tty/vt/vt_ioctl.c:850
 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: 0033:0x45ca29
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:00007fd688e88c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e6cc0 RCX: 000000000045ca29
RDX: 0000000020000240 RSI: 0000000000005609 RDI: 0000000000000006
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000037a R14: 00000000004c60c9 R15: 00007fd688e896d4

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/05/27 20:11 linux-4.19.y 2d16cf4817bc 9072c126 .config console log report ci2-linux-4-19
* Struck through repros no longer work on HEAD.