syzbot

 sign-in | mailing list | source | docs
🐞 Open [717]
🐞 Fixed [181]
🐞 Invalid [640]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: task hung in con_install

Status: auto-closed as invalid on 2020/08/16 15:03
Reported-by: syzbot+98494b1671f1ad93faed@syzkaller.appspotmail.com
First crash: 2115d, last: 2115d
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in con_install (2) serial 1 1 914d 914d 0/29 auto-obsoleted due to no activity on 2023/10/31 16:25
linux-4.19 INFO: task hung in con_install (2) 1 1 2061d 2061d 0/1 auto-closed as invalid on 2020/10/09 22:35
upstream INFO: task hung in con_install (3) kernel 1 32 10d 19d 0/29 upstream: reported on 2026/01/13 11:30
upstream INFO: task hung in con_install serial 1 6 2035d 2217d 0/29 closed as dup on 2020/08/16 15:20
linux-4.19 INFO: task hung in con_install 1 1 2194d 2194d 0/1 auto-closed as invalid on 2020/05/29 01:06

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.0:20305 blocked for more than 140 seconds.
      Not tainted 4.14.176-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D29136 20305   6374 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_timeout+0x946/0xe40 kernel/time/timer.c:1723
 __down_common kernel/locking/semaphore.c:221 [inline]
 __down+0x160/0x290 kernel/locking/semaphore.c:238
 down+0x57/0x80 kernel/locking/semaphore.c:62
 console_lock+0x24/0x70 kernel/printk/printk.c:2216
 con_install+0x46/0x490 drivers/tty/vt/vt.c:2891
 tty_driver_install_tty drivers/tty/tty_io.c:1225 [inline]
 tty_init_dev drivers/tty/tty_io.c:1338 [inline]
 tty_init_dev+0xe1/0x3a0 drivers/tty/tty_io.c:1315
 tty_open_by_driver drivers/tty/tty_io.c:1973 [inline]
 tty_open+0x410/0x9c0 drivers/tty/tty_io.c:2021
 chrdev_open+0x1fc/0x540 fs/char_dev.c:423
 do_dentry_open+0x732/0xe90 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0x8ca/0x3c50 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x29d/0x3f0 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x416661
RSP: 002b:00007f70f25607a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f70f25616d4 RCX: 0000000000416661
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007f70f25607d0
RBP: 000000000076bf00 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000064 R11: 0000000000000293 R12: 00000000ffffffff
R13: 0000000000000c0f R14: 00000000004ce414 R15: 000000000076bf0c
INFO: task syz-executor.5:20321 blocked for more than 140 seconds.
      Not tainted 4.14.176-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D28848 20321   6372 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 tty_open_by_driver drivers/tty/tty_io.c:1937 [inline]
 tty_open+0x352/0x9c0 drivers/tty/tty_io.c:2021
 chrdev_open+0x1fc/0x540 fs/char_dev.c:423
 do_dentry_open+0x732/0xe90 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0x8ca/0x3c50 fs/namei.c:3569
 do_filp_open+0x18e/0x250 fs/namei.c:3603
 do_sys_open+0x29d/0x3f0 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x416661
RSP: 002b:00007f203e6c17a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f203e6c26d4 RCX: 0000000000416661
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00007f203e6c17d0
RBP: 000000000076bf00 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000064 R11: 0000000000000293 R12: 00000000ffffffff
R13: 0000000000000c0f R14: 00000000004ce414 R15: 000000000076bf0c

Showing all locks held in the system:
1 lock held by khungtaskd/1057:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff81465bb3>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4544
1 lock held by in:imklog/6005:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff8191b886>] __fdget_pos+0xa6/0xc0 fs/file.c:769
2 locks held by syz-executor.0/20305:
 #0:  (tty_mutex){+.+.}, at: [<ffffffff8339eac2>] tty_open_by_driver drivers/tty/tty_io.c:1937 [inline]
 #0:  (tty_mutex){+.+.}, at: [<ffffffff8339eac2>] tty_open+0x352/0x9c0 drivers/tty/tty_io.c:2021
 #1:  (&tty->legacy_mutex){+.+.}, at: [<ffffffff833b51ef>] tty_lock+0x5f/0x70 drivers/tty/tty_mutex.c:19
1 lock held by syz-executor.5/20321:
 #0:  (tty_mutex){+.+.}, at: [<ffffffff8339eac2>] tty_open_by_driver drivers/tty/tty_io.c:1937 [inline]
 #0:  (tty_mutex){+.+.}, at: [<ffffffff8339eac2>] tty_open+0x352/0x9c0 drivers/tty/tty_io.c:2021

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

NMI backtrace for cpu 0
CPU: 0 PID: 1057 Comm: khungtaskd Not tainted 4.14.176-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x13e/0x194 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x139/0x17e lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5e2/0xb80 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 20297 Comm: syz-executor.4 Not tainted 4.14.176-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88809ed08100 task.stack: ffff88805bc48000
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x50 kernel/kcov.c:60
RSP: 0018:ffff88805bc4f820 EFLAGS: 00000283
RAX: 0000000000040000 RBX: ffff8880000a0050 RCX: ffffc9000866a000
RDX: 0000000000040000 RSI: ffffffff831eabd3 RDI: ffff88805bc4f8d8
RBP: 0000000000000050 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880000a002a
R13: 0000000000000000 R14: 00000000d0bba3bb R15: 000000000000004f
FS:  00007f61de66d700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31a24000 CR3: 000000005b8fa000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 writeb arch/x86/include/asm/io.h:65 [inline]
 vga16fb_fillrect+0x943/0x1880 drivers/video/fbdev/vga16fb.c:923
 bit_clear_margins+0x2a4/0x480 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x285/0x310 drivers/video/fbdev/core/fbcon.c:1320
 fbcon_do_set_font+0x6b3/0x990 drivers/video/fbdev/core/fbcon.c:2563
 fbcon_set_font+0x687/0x7c0 drivers/video/fbdev/core/fbcon.c:2654
 con_font_set drivers/tty/vt/vt.c:4182 [inline]
 con_font_op+0xb73/0xf70 drivers/tty/vt/vt.c:4247
 vt_ioctl+0x736/0x1f20 drivers/tty/vt/vt_ioctl.c:928
 tty_ioctl+0x6c5/0x1220 drivers/tty/tty_io.c:2661
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c869
RSP: 002b:00007f61de66cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f61de66d6d4 RCX: 000000000045c869
RDX: 00000000200000c0 RSI: 0000000000004b61 RDI: 0000000000000006
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000041b R14: 00000000004c6c3b R15: 000000000076bf0c
Code: 00 48 c7 c7 c0 90 ad 86 4c 89 3d fc bf fe 08 41 bd f4 ff ff ff e8 6c bd ee ff 48 c7 05 e6 bf fe 08 00 00 00 00 e9 be ed ff ff 90 <65> 48 8b 04 25 40 ee 01 00 48 85 c0 74 1a 65 8b 15 1b a7 a7 7e

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/04/18 15:02 linux-4.14.y c10b57a567e4 365fba24 .config console log report ci2-linux-4-14
* Struck through repros no longer work on HEAD.