Re: [Patch v2] selftests/mm: check content to see whether mremap corrupt data

[David Hildenbrand <david@redhat.com>]

On 02.09.25 10:13, Wei Yang wrote:
> On Tue, Sep 02, 2025 at 09:49:48AM +0200, David Hildenbrand wrote:
>>>> +	/*
>>>> +	 * To challenge spitting code, we will mremap page[x] of the
>>>> +	 * thp[x] into a smaller area, and trigger the split from that
>>>> +	 * smaller area. This will end up replacing the PMD mappings in
>>>> +	 * the thp_area by PTE mappings first, leaving the THPs unsplit.
>>>> +	 */
> 
> This confuse me a little. How about move "and trigger the split from that
> smaller area" to the end? So that I know mremap convert to pte-mapping and
> leave thp unsplit. Then we do the split.
> 

After spleeping over it, what about the following?

+       /*
+        * To challenge spitting code, we will mremap a single page of each
+        * THP (page[i] of thp[i]) in the thp_area into page_area. This will
+        * replace the PMD mappings in the thp_area by PTE mappings first,
+        * but leaving the THP unsplit, to then create a page-sized hole in
+        * the thp_area.
+        * We will then manually trigger splitting of all THPs through the
+        * single mremap'ed pages of each THP in the page_area.
+        */

-- 
Cheers

David / dhildenb