[CRIU] [PATCH 0/2] cr-check: use two features to verify userfaultfd availability

[Mike Rapoport]

On Tue, Aug 08, 2017 at 12:24:35PM +0200, Adrian Reber wrote:
> On Tue, Aug 08, 2017 at 10:05:55AM +0300, Mike Rapoport wrote:
> > This is somewhat v2 of "test/zdtm: do not allow running with --lazy-pages on
> > kernel without uffd" (1)
> > 
> > I've changed criu check verification for uffd availability and now instead
> > of '--feature lazy-pages' we'll have  '--feature uffd' and '--feature
> > uffd-noncoop'.
> > 
> > The first one checks if userfaultfd is available at all and the second
> > checks whether it supports non-cooperative mode.
> > 
> > [1] https://lists.openvz.org/pipermail/criu/2017-July/038757.html
> 
> Thinking about RPC (because of my runC PR) it would probably make sense
> to only answer the lazy_pages feature check with true if full UFFD
> support is in the kernel. There could be containers which can be lazily
> migrated without coop but it does not make much sense to offer such fine
> granularity for this feature via RPC. Either we have full UFFD support
> or none at all.

I think you are right and this will keep us on the safe side.
I'll prepare a patch a bit later.
 
> 		Adrian
> 

-- 
Sincerely yours,
Mike.