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Hello Brian.

Sorry, I'm unable to reproduce this on my workstation even when going up to 824 characters per /proc/self/cgroup. Could you please provide us with detailed reproduction scenario?

Thanks in advance.

Regards,
Jaromir.

Created attachment 1066368 [details]
Example output from valgrind of 'ps' segfaulting

Hi,

Sorry for the delay - have been on travel the last month.

See the attached output of "valgrind ps xawf -eo pid,user,cgroup,args"

Is it possible that I have more cgroup controllers mounted than you, causing the problem?

Thanks,

Brian

Hello Brian.

Everything is possible till you find a reliable reproducer and till we get a clue what's wrong after debugging with gdb. Try to reproduce your system state in a virtual machine and provide me with exact step by step instructions if it gets you to the crashing state again.

Thanks,
Jaromir.

Alright, try this:

1) Run "ps xawf -eo pid,user,cgroup,args" and make sure it exits without segfault.
2) Make sure at least the blkio, freezer, memory, cpuacct, and cpu controllers are mounted.  For me, they are mounted at /cgroup.
3) Create a cgroup with an excessively long name mkdir -p /cgroup/{blkio,freezer,memory,cpuacct,cpu}/condor/condor_var_lib_condor_execute_slot1_2.ede
4) Add current shell to excessively long cgroup name:
  - echo $$ > /cgroup/cpu/condor/condor_var_lib_condor_execute_slot1_2\@red-d9n3.unl.ede/tasks
  - echo $$ > /cgroup/cpuacct/condor/condor_var_lib_condor_execute_slot1_2\@red-d9n3.unl.ede/tasks
  - echo $$ > /cgroup/memory/condor/condor_var_lib_condor_execute_slot1_2\@red-d9n3.unl.ede/tasks
  - echo $$ > /cgroup/freezer/condor/condor_var_lib_condor_execute_slot1_2\@red-d9n3.unl.ede/tasks
  - echo $$ > /cgroup/blkio/condor/condor_var_lib_condor_execute_slot1_2\@red-d9n3.unl.ede/tasks
5) Run "ps xawf -eo pid,user,cgroup,args" again. This time, it should crash when it gets to the PID associated with your current shell.

I'm sorry. I did exactly what was written in #c6 and still get no crash.

In my case the difference active_cols-actual-tmpspace never gets negative.

In my case the active_cols is always equal to 131072 on the line 1843. The rest two values are too low to beat it (getting up to 681).

Ah - what terminal are you using?

I noticed that:

ps xawf -eo pid,user,cgroup,args

crashes but 

ps xawf -eo pid,user,cgroup,args | cat

works (the latter has 'ps' outputting to a pipe and not a TTY).  That indicates the issue might be related to terminal width.  I'm currently using a 213x42 terminal with:

# echo $TERM 
xterm-color

The length of the cgroup longest column is 381 characters; I see a segfault at a terminal of width 252 characters and no longer at 253.

(In reply to Brian Bockelman from comment #10)
> Ah - what terminal are you using?

I tried konsole, xfce4 terminal and xterm -> no crash. But when running the debug binary in xterm, the value really gets negative. So, at least this one got sorted out. Thanks.


> I noticed that:
> 
> ps xawf -eo pid,user,cgroup,args
> 
> crashes but 
> 
> ps xawf -eo pid,user,cgroup,args | cat
> 
> works (the latter has 'ps' outputting to a pipe and not a TTY).  That
> indicates the issue might be related to terminal width.  I'm currently using
> a 213x42 terminal with:

I tried several widths and still getting no crash. But that could still be caused by differences in the environment.


> # echo $TERM 
> xterm-color
> 
> The length of the cgroup longest column is 381 characters; I see a segfault
> at a terminal of width 252 characters and no longer at 253.

Ok. I'll try several widths. Anyway, the code probably needs to be analysed.

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