Re: [PATCH v2] mm: thp: fix flags for pmd migration when split

[Zi Yan]

On 11 Dec 2018, at 3:21, Konstantin Khlebnikov wrote:
>
> Write/read-only is encoded into migration entry.
> I suppose there should be something like this:
>
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2151,16 +2151,21 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
>
>                 entry = pmd_to_swp_entry(old_pmd);
>                 page = pfn_to_page(swp_offset(entry));
> +               write = is_write_migration_entry(entry);
> +               young = false;
> +               soft_dirty = pmd_swp_soft_dirty(old_pmd);
>         } else
>  #endif
> +       {
>                 page = pmd_page(old_pmd);
> +               if (pmd_dirty(old_pmd))
> +                       SetPageDirty(page);
> +               write = pmd_write(old_pmd);
> +               young = pmd_young(old_pmd);
> +               soft_dirty = pmd_soft_dirty(old_pmd);
> +       }
>         VM_BUG_ON_PAGE(!page_count(page), page);
>         page_ref_add(page, HPAGE_PMD_NR - 1);
> -       if (pmd_dirty(old_pmd))
> -               SetPageDirty(page);
> -       write = pmd_write(old_pmd);
> -       young = pmd_young(old_pmd);
> -       soft_dirty = pmd_soft_dirty(old_pmd);
>
>         /*
>          * Withdraw the table only after we mark the pmd entry invalid.
>

This one should fix the issue. Thanks.

Reviewed-by: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
Fixes 84c3fc4e9c563 ("mm: thp: check pmd migration entry in common path")

Do we need to cc: stable@xxxxxxxxxxxxxxx # 4.14+ ?


--
Best Regards,
Yan Zi

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