[CRIU] Error CRIU restore because pid not matched

[Aris Setyawan]

Hi Chris,

> For simple situations you may be able to start a script in the new namespace that restores, waits, and dumps again

Yes this is absolutely will work, If I use criu C API, but I currently
use criu command-line (then call it frm PHP script).

The problem I faced is, because I use separated command line to
restore and dump process (a web service process).
Using, "unshare" command, I successfully run restore process in new
namespace, to avoid PID mismatch. If I detach criu from my own process
(-d option), then the new namespace inherited from criu, will be
destroyed.
If I'm not using -d option, then I can dump the process again.

Btw,
I think, the sequences of "restore-process-dump" can be done with criu
service + RPC.
Is that possible? If yes, I can start criu service using "unshare -p
--fork --mount-proc" command.

On 1/3/15, Christopher Covington <cov at codeaurora.org> wrote:
> Hi Aris,
>
> On 12/31/2014 06:20 PM, Aris Setyawan wrote:
>>> P.S. I'd appreciate if any discussion about CRIU happens with the
>>> mailing
>>> list in Cc. My responsiveness throughput is limited :) but on the
>>> mailing
>>> list there are quite a lot of other people that can help.
>>
>> Ok.
>>
>>> [1] http://criu.org/When_C/R_fails
>>
>> Ok, I successfully restore it using unshare command, after dump it
>> (test.sh process):
>>
>> 	criu dump -t 422439 --images-dir /tmp/test --shell-job
>> 	unshare -p --fork --mount-proc criu restore --images-dir /tmp/test
>> --shell-job
>>
>> And the test.sh process, run as a child process (this is because we
>> can not running restore with -d option):
>>
>> 	$ ps ax | grep test
>> 	 422516 pts/0    S      0:00 /path/unshare -p --fork --mount-proc
>> /path/criu restore --images-dir /tmp/test --shell-job
>> 	 422517 pts/0    S      0:00 /path/criu restore --images-dir
>> /tmp/test --shell-job
>> 	 422518 pts/0    S      0:15 /bin/sh ./test.sh
>>
>> In my use case, I need to dump test.sh process again (and it's state)
>> and then restore it again, then doing a computation. And then dump it
>> again.
>>
>> New problem, come. How I can dump the process again?
>
> For simple situations you may be able to start a script in the new
> namespace
> that restores, waits, and dumps again. If that won't work, you may want to
> look into using the setns system call to enter the namespace.
>
> http://man7.org/linux/man-pages/man2/setns.2.html
>
> A brief look at the --namespaces option and the calls to switch_ns() [which
> calls setns()] makes me think CRIU currently does not have such
> functionality,
> but I may be misinterpreting or overlooking something.
>
> Chris
>
> --
> Qualcomm Innovation Center, Inc.
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