[Vserver] [Re:] vcontext/login CPU usage at 100%

From: Luis <luis_at_riseup.net>
Date: Sat 24 Mar 2007 - 17:26:07 GMT
Message-ID: <46055F2F.7020408@riseup.net>

Summary:
===================================
After a "vserver XX enter", if vcontext/login gets disconnected from its
terminal its CPU usage steadily increases to 100%.
===================================

Description:
===================================
We are having exactly the same problem this guy had:
http://archives.linux-vserver.org/200701/0054.html

Here is his description of the problem and how he managed to reproduce it:

> First problem:
> In some situations my CPU was burning like hell for days before I
> noticed it.
> This was the vcontext/login process, the one running when using the
> command "vserver XX enter".
> If it happens that the process is disconnected from its terminal it
> eats all the CPU :-(
>
> Apparently it happens when the session is not ended properly
> (disconnections, etc)
> I could reproduce the problem as follow:
> * ssh to the server as normal user
> * sudo su -
> * vserver XX enter
> * now from another term, kill -9 on either of the two su processes
> ("su -" or "-su")
> At that point the session in the vserver ends but vcontext is still
> hooked to the current terminal so cpu is fine.
> * now quit the current terminal
> At that point vcontext is not hooked to any terminal (vps ax => "?"
> on the tty column) and using top you see it's running 100% cpu, ~ 80%
> system and 20% user.

We can reproduce this problem following exactly the same steps. After
quitting the terminal, CPU usage steadily increases to 100%.

Let us know if there's any other information that might be useful. Also,
if you can't reproduce the problem on your side, maybe we can help
debugging it from here. Anyway, let us know.
===================================

Environment:
===================================

Kernel
==============
$ cat /proc/version
Linux version 2.6.20.1-vs2.2.0-rc15 (root@satanbuild) (gcc version
3.4.6) #1 SMP Fri Mar 2 20:28:38 BRT 2007
==============

CPU
==============
$ cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 43
model name : AMD Athlon(tm) 64 X2 Dual Core Processor 3800+
stepping : 1
cpu MHz : 2010.339
cache size : 512 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext
fxsr_opt lm 3dnowext 3dnow pni lahf_lm cmp_legacy
bogomips : 4023.12
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp

processor : 1
vendor_id : AuthenticAMD
cpu family : 15
model : 43
model name : AMD Athlon(tm) 64 X2 Dual Core Processor 3800+
stepping : 1
cpu MHz : 2010.339
cache size : 512 KB
physical id : 0
siblings : 2
core id : 1
cpu cores : 2
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext
fxsr_opt lm 3dnowext 3dnow pni lahf_lm cmp_legacy
bogomips : 4020.87
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp
==============

Modules
==============
Monolithic kernel, no modules support.
==============

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

testme.sh output:
===================================
Linux-VServer Test [V0.17] Copyright (C) 2003-2006 H.Poetzl
chcontext is working.
chbind is working.
Linux 2.6.20.1-vs2.2.0-rc15 #1 SMP Fri Mar 2 20:28:38 BRT 2007 x86_64
Ea 0.30.212 236/glibc (S*) <v13,net,v21>
VCI: 0002:0200 236 03000417 (TbLgnsP)

---
[000]# succeeded.
[001]# succeeded.
[011]# succeeded.
[031]# succeeded.
[101]# succeeded.
[102]# succeeded.
[201]# succeeded.
[202]# succeeded.
===================================
testfs.sh output:
===================================
Legacy mode
==============
Linux-VServer FS Test [V0.15] Copyright (C) 2005-2006 H.Poetzl
Linux 2.6.20.1-vs2.2.0-rc15 x86_64/0.30.212
VCI:  0002:0200 236 03000417 (ID24)
---
testing ext2 filesystem ...
[000]. xattr related tests ...
[101]. [102]. [103]* [104]* [106]. [108]. [109]*
[112]. [113]* [114]* [115]. [116]* [117]. [118]. [119]*
[121]* [122]* [123]* [124]* [128]. [129].
---
testing ext3 filesystem ...
[000]. xattr related tests ...
[101]. [102]. [103]* [104]* [106]. [108]. [109]*
[112]. [113]* [114]* [115]. [116]* [117]. [118]. [119]*
[121]* [122]* [123]* [124]* [128]. [129].
---
testing xfs filesystem ...
[000]. xattr related tests ...
[101]. [102]. [103]* [104]* [106]. [108]. [109]*
[112]. [113]* [114]* [115]. [116]* [117]. [118]. [119]*
[121]* [122]* [123]* [124]* [128]. [129].
---
testing reiser filesystem ...
[000]. xattr related tests ...
[101]. [102]. [103]* [104]* [106]. [108]. [109]*
[112]. [113]* [114]* [115]. [116]* [117]. [118]. [119]*
[121]* [122]* [123]* [124]* [128]. [129].
---
testing jfs filesystem ...
[000]. xattr related tests ...
[101]*
==============
New-style config
==============
Linux-VServer FS Test [V0.15] Copyright (C) 2005-2006 H.Poetzl
Linux 2.6.20.1-vs2.2.0-rc15 x86_64/0.30.212
VCI:  0002:0200 236 03000417 (ID24)
---
testing ext2 filesystem ...
[000]. xattr related tests ...
[101]. [102]. [103]. [104]. [106]. [108]. [109].
[112]. [113]. [114]. [115]. [116]* [117]* [118]. [119].
[121]. [122]. [123]. [124]. [128]. [129].
---
testing ext3 filesystem ...
[000]. xattr related tests ...
[101]. [102]. [103]. [104]. [106]. [108]. [109].
[112]. [113]. [114]. [115]. [116]* [117]* [118]. [119].
[121]. [122]. [123]. [124]. [128]. [129].
---
testing xfs filesystem ...
[000]. xattr related tests ...
[101]. [102]. [103]. [104]. [106]. [108]. [109].
[112]. [113]. [114]. [115]. [116]* [117]* [118]. [119].
[121]. [122]. [123]. [124]. [128]. [129].
---
testing reiser filesystem ...
[000]. xattr related tests ...
[101]. [102]. [103]. [104]. [106]. [108]. [109].
[112]. [113]. [114]. [115]. [116]* [117]* [118]. [119].
[121]. [122]. [123]. [124]. [128]. [129].
---
testing jfs filesystem ...
[000]. xattr related tests ...
[101]*
==============
===================================
-- 
Luis
OpenPGP key:
0xA53D8214 | keyserver.noreply.org

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