On Tue, 7 Jan 2025 14:25:53 +0000 Ryan Roberts <ryan.roberts@xxxxxxx> wrote:
> After commit b1f202060afe ("mm: remap unused subpages to shared zeropage
> when splitting isolated thp"), cow test cases involving swapping out
> THPs via madvise(MADV_PAGEOUT) started to be skipped due to the
> subsequent check via pagemap determining that the memory was not
> actually swapped out. Logs similar to this were emitted:
>
> ...
>
> The commit in question introduces the behaviour of scanning THPs and if
> their content is predominantly zero, it splits them and replaces the
> pages which are wholly zero with the zero page. These cow test cases
> were getting caught up in this.
>
> So let's avoid that by filling the contents of all allocated memory with
> a non-zero value. With this in place, the tests are passing again.
>
Thanks, I'll add
Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage when splitting isolated thp")
...
Cc: Usama Arif <usamaarif642@xxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
