[CRIU] remap_dead_pid test hang?

[Tycho Andersen]

On Fri, Mar 20, 2015 at 12:59:43AM +0300, Pavel Emelyanov wrote:
> On 03/20/2015 12:42 AM, Tycho Andersen wrote:
> > On Thu, Mar 19, 2015 at 10:05:09PM +0300, Pavel Emelyanov wrote:
> >> On 03/19/2015 10:01 PM, Pavel Emelyanov wrote:
> >>> On 03/19/2015 09:54 PM, Tycho Andersen wrote:
> >>>> On Thu, Mar 19, 2015 at 07:36:41PM +0300, Pavel Emelyanov wrote:
> >>>>> On 03/19/2015 05:54 PM, Tycho Andersen wrote:
> >>>>>> Hi all,
> >>>>>>
> >>>>>> While testing the cgroup property restore patch, I noticed that the
> >>>>>> remap_dead_pid test seems to hang both with my patch and the current
> >>>>>> master. Has anyone else noticed this?
> >>>>>
> >>>>> No. We have Jenkins running full zdtm suite (and more) in 7x24 manner
> >>>>> and though it fails sometimes, but we haven't met any issues with this
> >>>>> particular test.
> >>>>>
> >>>>> Does the test hang by itself, or after restore?
> >>>>
> >>>> How do I tell? It looks like it's just hung:
> >>>>
> >>>> root     32749  0.0  0.1  11652  3292 pts/1    S    18:49   0:00 /bin/bash ./zdtm.sh --ct -r static/remap_dead_pid
> >>>> root       314  0.0  0.0   4196   644 pts/1    S    18:49   0:00  \_ ./zdtm_ct ./zdtm.sh -r static/remap_dead_pid
> >>>> root       370  0.0  0.1  11752  3476 ?        Ss   18:49   0:00      \_ /bin/bash ./zdtm.sh -r static/remap_dead_pid
> >>>> root     15963  0.0  0.1  11752  2372 ?        S    18:49   0:00          \_ /bin/bash ./zdtm.sh -r static/remap_dead_pid
> >>>> root     15964  0.0  0.1   8464  2332 ?        S    18:49   0:00              \_ make -C zdtm/live/static remap_dead_pid.pid
> >>>> 18943    17937  0.0  0.0   4492   816 ?        S    18:49   0:00                  \_ ./remap_dead_pid --pidfile=remap_dead_pid.pid --outfile=remap_dead_pid.out
> >>>> 18943    17940  0.0  0.0   4492   104 ?        Ss   18:49   0:00                      \_ ./remap_dead_pid --pidfile=remap_dead_pid.pid --outfile=remap_dead_pid.out
> >>>> 18943    17941  0.0  0.0   4492  1136 ?        S    18:49   0:00                          \_ ./remap_dead_pid --pidfile=remap_dead_pid.pid --outfile=remap_dead_pid.out
> >>>
> >>> Hm... :) There should be a directory where criu is supposed to put it's output
> >>> (logs and images), the test/dump/ one if I'm not mistaken. Then you can check
> >>> the remap_dead_pid's directory to container dump.log or restore.log to find
> >>> out whether any of those actions took place.
> >>>
> >>
> >> Ah, no, what am I telling?! Sorry, of course there hasn't been any dumps
> >> yet, the make $test.pid is still there. And it's not finished because the
> >> process 816 hasn't exited. Yet. Can you strace them all to check what are
> >> they currently doing?
> > 
> > Yes, 17940 was in waitpid4, and 17941 was in nanosleep. I guess that
> > means the kill() in that test failed somehow? 
> 
> Looks like yes. What bothers me is that the task is killed with SIGINT,
> not SIGKILL. Is this signal blocked or ignored by 17941? Can you check
> it in /proc/pid/status?

Doesn't look like it,

http://paste.ubuntu.com/10630380/

However, when I switch it to SIGKILL it does seem to succeed every
time for me.

Tycho

> > Is there a race there that I am missing?
> 
> Shouldn't be. The code is pretty straightforward -- fork, kill then wait.
> 
> Thanks,
> Pavel
>