Dear Maintainer,
*** Reporter, please consider answering these questions, where appropriate
***
* What led up to the situation?
I have a problem to send random text to the console (/dev/ttyS1)
without stopping,
after a few minutes, the box becomes unresponsive. I can see wa
consumes the
CPU, but the box does not have much disk I/O operation. Also, I can
see agetty
is in D state.
top - 08:27:30 up 10 min, 1 user, load average: 1.22, 0.41, 0.21
Tasks: 161 total, 3 running, 158 sleeping, 0 stopped, 0 zombie
%Cpu0 : 0.3 us, 0.0 sy, 0.0 ni, 99.7 id, 0.0 wa, 0.0 hi, 0.0 si,
0.0 st
%Cpu1 : 0.0 us, 0.3 sy, 0.0 ni, 0.0 id, 99.7 wa, 0.0 hi, 0.0 si,
0.0 st
%Cpu2 : 0.0 us, 0.0 sy, 0.0 ni, 0.0 id,100.0 wa, 0.0 hi, 0.0 si,
0.0 st
%Cpu3 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si,
0.0 st
KiB Mem: 8180376 total, 767372 used, 7413004 free, 64420 buffers
KiB Swap: 0 total, 0 used, 0 free. 317000 cached Mem
admin@str-s6100-acs-4:~$ ps aux | grep D
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 161 0.0 0.0 0 0 ? D 00:12 0:01
[jbd2/sda4-8]
root 197 0.0 0.0 0 0 ? D< 00:12 0:01 [loop1]
root 198 0.0 0.0 0 0 ? D 00:12 0:00
[jbd2/loop1-8]
root 15101 0.0 0.0 0 0 ? Ds 22:20 0:00 [agetty]
root 15120 0.0 0.0 27860 2384 ? D 22:21 0:00
/usr/sbin/logrotate /etc/logrotate.conf
root 15123 0.0 0.0 27856 2468 ? D 22:22 0:00
/usr/sbin/logrotate /etc/logrotate.conf
admin 15130 0.0 0.0 11132 940 pts/10 S+ 22:22 0:00 grep D
* What exactly did you do (or not do) that was effective (or
ineffective)?
Continuously sending random text to console cause kernel to become
unresponsive.
* What was the outcome of this action?
The kernel becomes unresponsive.
* What outcome did you expect instead?
I have tried the same experiment on Debian stretch with 4.9 kernel.
stretch is working fine.
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