[lxc-users] LXCFS and ProcPS Interaction Issue

[Serge Hallyn]

Quoting Robert Pendell (shinji at elite-systems.org):
> On Mon, Jun 1, 2015 at 8:42 PM, Serge Hallyn <serge.hallyn at ubuntu.com> wrote:
> > Quoting Robert Pendell (shinji at elite-systems.org):
> >> First some basic information so you know my environment...
> >> Host: Linode
> >> OS: Ubuntu 14.04.2
> >> Kernel: Host supplied 4.0.1 -- also tested against PV-Grub loaded 4.1-RC4
> >> Container Privilage: Unprivileged.
> >> shinji at icarus:/proc> apt-cache policy lxcfs
> >> lxcfs:
> >>   Installed: 0.7-0ubuntu2~ubuntu14.04.1~ppa1
> >>   Candidate: 0.7-0ubuntu2~ubuntu14.04.1~ppa1
> >>   Version table:
> >>  *** 0.7-0ubuntu2~ubuntu14.04.1~ppa1 0
> >>         500 http://ppa.launchpad.net/ubuntu-lxc/daily/ubuntu/
> >> trusty/main amd64 Packages
> >>         100 /var/lib/dpkg/status
> >>
> >> I literally just noticed this today.  When LXCFS is started and
> >> running ProcPS throws a Floating Point Exception.  I do not know why
> >> this is the case.  Oddly enough stopping LXCFS on the host and
> >> restarting the container makes the bug go away.  Ideas?  Anything I
> >> can test to isolate?
> >
> > Can you build 0.9.0 from the wily sources, just to make sure this isn't
> > somethign fixed upstream?
> >
> > Also, if you can run lxcfs under gdb and get stack trace when it crashes
> > that woudl be helpful.
> >
> >> LXCFS Stopped
> >> shinji at trusty-x86:~> ps u
> >> USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
> >> shinji    1506  0.0  0.1   5816  3536 pts/4    Ss+  12:42   0:00 -bash
> >> shinji    1519  0.0  0.1   5404  2684 pts/4    S+   12:42   0:00 tmux -2 -f /usr
> >> shinji    1573  0.3  0.1   5696  3412 pts/5    Ss   12:42   0:00 /bin/bash
> >> shinji    1679  0.0  0.1   5228  2340 pts/5    R+   12:42   0:00 ps u
> >>
> >> LXCFS Started
> >> shinji at trusty-x86:~> ps u
> >> USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
> >> Signal 8 (FPE) caught by ps (procps-ng version 3.3.9).
> >> shinji    1521  0.0ps:display.c:66: please report this bug
> >> Floating point exception
> >>
> 
> I could but I guess I forgot to mention on here that the issue was
> already identified when I ran a ticket on LXC.

Ah, great, thanks.

> The issue is identified by LXCFS not handling the situation where
> /proc/meminfo is empty.  I don't see a change that would make it
> handle it better in 0.9.  The empty scenario happens in a few
> conditions.
> 
> The memory cgroup isn't compiled into the kernel being used at all
> The memory cgroup functions are compiled in but are disabled at boot
> time (cgroup_disable=memory)
> The memory cgroup functions are compiled in but are disabled by
> default at boot time
> 
> See ticket: https://github.com/lxc/lxcfs/issues/30
> 
> The first scenario applies to me above.
> 
> Robert Pendell
> shinji at elite-systems.org
> A perfect world is one of chaos.
> Keybase: http://keybase.io/shinji257
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