syzbot


INFO: task hung in con_write

Status: auto-closed as invalid on 2020/10/15 09:20
Reported-by: syzbot+f222fc6433e7e0ac3882@syzkaller.appspotmail.com
First crash: 857d, last: 790d
similar bugs (3):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in con_write (2) 3 762d 810d 0/23 auto-closed as invalid on 2020/10/13 06:51
upstream INFO: task hung in con_write 1 975d 975d 0/23 auto-closed as invalid on 2020/03/14 17:26
linux-4.14 INFO: task hung in con_write 1 820d 820d 0/1 auto-closed as invalid on 2020/09/14 21:41

Sample crash report:
INFO: task syz-executor.1:15390 blocked for more than 140 seconds.
      Not tainted 4.19.128-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D28352 15390   6568 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
 con_flush_chars drivers/tty/vt/vt.c:3215 [inline]
 con_flush_chars drivers/tty/vt/vt.c:3207 [inline]
 con_write+0x7c/0xe0 drivers/tty/vt/vt.c:3139
 n_tty_write+0xa69/0x1080 drivers/tty/n_tty.c:2354
 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: 0033:0x45ca59
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:00007f0e5a8b0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000050d1a0 RCX: 000000000045ca59
RDX: 0000000000001006 RSI: 0000000020001440 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000cff R14: 00000000004cf549 R15: 00007f0e5a8b16d4
INFO: task syz-executor.0:15420 blocked for more than 140 seconds.
      Not tainted 4.19.128-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D29440 15420   6449 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_fb_ioctl+0x3e1/0x9c0 drivers/video/fbdev/core/fbmem.c:1109
 fb_ioctl+0xda/0x120 drivers/video/fbdev/core/fbmem.c:1230
 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: 0033:0x45ca59
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:00007f4316cfec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e4fa0 RCX: 000000000045ca59
RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000004
RBP: 000000000078c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000002f7 R14: 00000000004c575e R15: 00007f4316cff6d4
INFO: task syz-executor.5:15425 blocked for more than 140 seconds.
      Not tainted 4.19.128-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D29280 15425   6959 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
 vcs_open+0x62/0xc0 drivers/tty/vt/vc_screen.c:660
 chrdev_open+0x219/0x5c0 fs/char_dev.c:423
 do_dentry_open+0x4a8/0x1160 fs/open.c:796
 do_last fs/namei.c:3421 [inline]
 path_openat+0xe06/0x2eb0 fs/namei.c:3537
 do_filp_open+0x1a1/0x280 fs/namei.c:3567
 do_sys_open+0x3aa/0x510 fs/open.c:1085
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x416851
Code: 75 14 b8 02 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 19 00 00 c3 48 83 ec 08 e8 0a fa ff ff 48 89 04 24 b8 02 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fa ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f2f5d3df7a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000416851
RDX: 0000000000000000 RSI: 0000000000000401 RDI: 00007f2f5d3df850
RBP: 000000000078bfa0 R08: 000000000000000f R09: 0000000000000000
R10: 00007f2f5d3e09d0 R11: 0000000000000293 R12: 00000000ffffffff
R13: 0000000000000c40 R14: 00000000004ce973 R15: 00007f2f5d3e06d4

Showing all locks held in the system:
1 lock held by khungtaskd/1079:
 #0: 0000000012096e04 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by in:imklog/6136:
 #0: 0000000031e1aeda (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:767
2 locks held by agetty/6347:
 #0: 00000000e7515d0e (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
 #1: 00000000f59a9c45 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x217/0x1a50 drivers/tty/n_tty.c:2154
2 locks held by kworker/u4:12/6898:
4 locks held by syz-executor.1/15390:
 #0: 00000000e7515d0e (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
 #1: 0000000084f7e4fa (&tty->atomic_write_lock){+.+.}, at: tty_write_lock+0x1e/0x80 drivers/tty/tty_io.c:886
 #2: 00000000dddae3ff (&tty->termios_rwsem){++++}, at: n_tty_write+0x1b2/0x1080 drivers/tty/n_tty.c:2314
 #3: 00000000b8e476f1 (&ldata->output_lock){+.+.}, at: n_tty_write+0xa2f/0x1080 drivers/tty/n_tty.c:2353
3 locks held by syz-executor.0/15391:

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

NMI backtrace for cpu 1
CPU: 1 PID: 1079 Comm: khungtaskd Not tainted 4.19.128-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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 6898 Comm: kworker/u4:12 Not tainted 4.19.128-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
RIP: 0010:find_held_lock+0x17f/0x200 kernel/locking/lockdep.c:3541
Code: 85 c0 75 15 41 83 ed 01 49 83 ec 28 41 83 fd ff 0f 85 3c ff ff ff 45 31 e4 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <0f> b6 14 02 4c 89 f0 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 26 5b
RSP: 0018:ffff88804fc9fae0 EFLAGS: 00000802
RAX: dffffc0000000000 RBX: ffffffff8b6dbaa0 RCX: ffff88804fc9fb58
RDX: 1ffff11009f93f6b RSI: ffffffff88b933a0 RDI: ffff888051e0ced0
RBP: 0000000000000004 R08: 0000000000000000 R09: ffffed1015cc473b
R10: ffffed1015cc473a R11: ffff8880ae6239d3 R12: ffff888051e0cec0
R13: 0000000000000003 R14: ffff88804fc9fb58 R15: ffffffff88b933a0
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9b2def93a0 CR3: 00000000a45c2000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __lock_release kernel/locking/lockdep.c:3676 [inline]
 lock_release+0x244/0x810 kernel/locking/lockdep.c:3926
 rcu_lock_release include/linux/rcupdate.h:247 [inline]
 rcu_read_unlock include/linux/rcupdate.h:681 [inline]
 batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:952 [inline]
 batadv_iv_ogm_schedule_buff+0x7c2/0x1230 net/batman-adv/bat_iv_ogm.c:1006
 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:1050 [inline]
 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:1043 [inline]
 batadv_iv_send_outstanding_bat_ogm_packet+0x5e0/0x7a0 net/batman-adv/bat_iv_ogm.c:1869
 process_one_work+0x892/0x1580 kernel/workqueue.c:2155
 worker_thread+0x96/0xe20 kernel/workqueue.c:2298
 kthread+0x30b/0x410 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-19 2020/06/17 09:19 linux-4.19.y 3fc898571b97 b9f3810b .config log report
ci2-linux-4-19 2020/04/11 08:02 linux-4.19.y dda0e2920330 a8c6a3f8 .config log report