Re: [PATCH v2 5/6] selftests/mm: add uffd unit test for UFFDIO_POISON

[Peter Xu]

On Thu, Jun 29, 2023 at 01:50:39PM -0700, Axel Rasmussen wrote:
> The test is pretty basic, and exercises UFFDIO_POISON straightforwardly.
> We register a region with userfaultfd, in missing fault mode. For each
> fault, we either UFFDIO_COPY a zeroed page (odd pages) or UFFDIO_POISON
> (even pages). We do this mix to test "something like a real use case",
> where guest memory would be some mix of poisoned and non-poisoned pages.
> 
> We read each page in the region, and assert that the odd pages are
> zeroed as expected, and the even pages yield a SIGBUS as expected.
> 
> Why UFFDIO_COPY instead of UFFDIO_ZEROPAGE? Because hugetlb doesn't
> support UFFDIO_ZEROPAGE, and we don't want to have special case code.
> 
> Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>

Acked-by: Peter Xu <peterx@xxxxxxxxxx>

-- 
Peter Xu