Re: [PATCH V3] selftests: vm: Add test for Soft-Dirty PTE bit

On 2/28/22 2:37 AM, David Hildenbrand wrote:

On 24.02.22 22:23, Muhammad Usama Anjum wrote:

...

This introduces three tests:

1. Sanity check soft dirty basic semantics: allocate area, clean, dirty,

check if the SD bit flipped. 2) Check VMA reuse: validate the VM_SOFTDIRTY usage 3) Check soft-dirty on huge pages

This was motivated by Will Deacon's fix commit 912efa17e512 ("mm: proc: Invalidate TLB after clearing soft-dirty page state"). I was tracking the same issue that he fixed, and this test would have caught it.

A note that madv_populate.c already contains some SOFTDIRTY tests regarding MADV_POPULATE. Eventually we want to factor out softdirty/pagemap handling+checks for easier reuse.

Is this patch unnecessary then?

thanks, -- Shuah