Re: [PATCH 1/3] mm: change huge_ptep_clear_flush() to return the original pte

[Mike Kravetz]

On 4/29/22 01:14, Baolin Wang wrote:
> It is incorrect to use ptep_clear_flush() to nuke a hugetlb page
> table when unmapping or migrating a hugetlb page, and will change
> to use huge_ptep_clear_flush() instead in the following patches.
> 
> So this is a preparation patch, which changes the huge_ptep_clear_flush()
> to return the original pte to help to nuke a hugetlb page table.
> 
> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> ---
>  arch/arm64/include/asm/hugetlb.h   |  4 ++--
>  arch/arm64/mm/hugetlbpage.c        | 12 +++++-------
>  arch/ia64/include/asm/hugetlb.h    |  4 ++--
>  arch/mips/include/asm/hugetlb.h    |  9 ++++++---
>  arch/parisc/include/asm/hugetlb.h  |  4 ++--
>  arch/powerpc/include/asm/hugetlb.h |  9 ++++++---
>  arch/s390/include/asm/hugetlb.h    |  6 +++---
>  arch/sh/include/asm/hugetlb.h      |  4 ++--
>  arch/sparc/include/asm/hugetlb.h   |  4 ++--
>  include/asm-generic/hugetlb.h      |  4 ++--
>  10 files changed, 32 insertions(+), 28 deletions(-)

The above changes look straight forward.
Happy that you Cc'ed impacted arch maintainers so they can at least
have a look.

The only user of huge_ptep_clear_flush() today is hugetlb_cow/wp() in
mm/hugetlb.c.  Any reason why you did not change that code?  At least
cast the return of huge_ptep_clear_flush() to void with a comment?
Not absolutely necessary.

Acked-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
-- 
Mike Kravetz