[CRIU] Preserve the "dumpable" flag on criu dump/restore.

[Pavel Emelyanov]

On 05/13/2014 02:37 AM, Filipe Brandenburger wrote:
> Hi,
> 
> Sorry for the double report, but I didn't know whether Bugzilla or
> mailing list was more appropriate...
> 
> I found this issue with the files in /proc/$pid being owned by
> root:root after a criu restore. I traced it to the fact that the
> "dumpable" flag for the task does not get preserved over a criu
> dump/restore.
> 
> I filed this bug about it:
> https://bugzilla.openvz.org/show_bug.cgi?id=2968

Good catch, thank you! :)

> And I sent this patch which fixes the issue:
> http://2968.bugzilla.openvz.org/attachment.cgi?id=2147

Can you please send this patch to the mailing list, please? I
glanced through it via bugzilla interface and have one comment,
and it's more convenient to do this conversation over the 
mailing thread.

> While testing the patch with zdtm, I also found that it caused
> static/cow01 to break. After some investigation, I got to the
> conclusion that cow01 was inherently broken and without the "dumpable"
> flag being preserved it would always succeed even though it was not
> really checking whether pages are COWed...

Ouch... Can you shed more light on this?

> On the other hand, after the fix to preserve the "dumpable" flag, then
> test static/cow01 was failing consistently. It turns out that it seems
> that COW is not really working as expected, and now that the test was
> fixed it's showing that this is actually broken.
> 
> I filed this bug to report the fact that the static/cow01 test seems
> to be broken:
> https://bugzilla.openvz.org/show_bug.cgi?id=2967
> 
> It seems that COW support itself also needs to be fixed. I'm currently
> looking into it but I'm not really sure where the problem is yet.

Great!

> Let me know if you have any questions about the dumpable flag patch.

Thanks,
Pavel