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

[Adrian Reber]

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.

		Adrian