Changes

* Only MAP_PRIVATE | MAP_ANONYMOUS will be supported in the 1st version due to kernel constraints.

* Only MAP_PRIVATE | MAP_ANONYMOUS will be supported in the 1st version due to kernel constraints.

* Userfault is known not to map one page into two places. Thus -- COW-ed pages will get COW-ed.

* Userfault is known not to map one page into two places. Thus -- COW-ed pages will get COW-ed.

* Andrea (author) states that UFFDIO_REMAP might be slow as compared to UUFDIO_COPY. Probably it makes sense to copy data into tasks, not move.

* Andrea (author) states that UFFDIO_REMAP might be slow as compared to UFFDIO_COPY. Probably it makes sense to copy data into tasks, not move.

* Unmaps and mremaps can screw things up. Either we have to make uffd-s per VMA or add events about such things.

* Unmaps and mremaps can screw things up. Either we have to make uffd-s per VMA or add events about such things.

* Forks are even worse -- kid will just populate its memory with zero pages :(

* Forks are even worse -- kid will just populate its memory with zero pages :(