Re: [PATCH v3 4/5] mm/khugepaged: Convert alloc_charge_hpage() to use folios

[Yang Shi]

On Fri, Oct 20, 2023 at 11:34 AM Vishal Moola (Oracle)
<vishal.moola@xxxxxxxxx> wrote:
>
> Also remove count_memcg_page_event now that its last caller no longer uses
> it and reword hpage_collapse_alloc_page() to hpage_collapse_alloc_folio().
>
> This removes 1 call to compound_head() and helps convert khugepaged to
> use folios throughout.
>
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>

Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>

> ---
>  include/linux/memcontrol.h | 14 --------------
>  mm/khugepaged.c            | 17 ++++++++++-------
>  2 files changed, 10 insertions(+), 21 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index ab94ad4597d0..3126bde982e8 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1080,15 +1080,6 @@ static inline void count_memcg_events(struct mem_cgroup *memcg,
>         local_irq_restore(flags);
>  }
>
> -static inline void count_memcg_page_event(struct page *page,
> -                                         enum vm_event_item idx)
> -{
> -       struct mem_cgroup *memcg = page_memcg(page);
> -
> -       if (memcg)
> -               count_memcg_events(memcg, idx, 1);
> -}
> -
>  static inline void count_memcg_folio_events(struct folio *folio,
>                 enum vm_event_item idx, unsigned long nr)
>  {
> @@ -1565,11 +1556,6 @@ static inline void __count_memcg_events(struct mem_cgroup *memcg,
>  {
>  }
>
> -static inline void count_memcg_page_event(struct page *page,
> -                                         int idx)
> -{
> -}
> -
>  static inline void count_memcg_folio_events(struct folio *folio,
>                 enum vm_event_item idx, unsigned long nr)
>  {
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 9efd8ff68f06..6a7184cd291b 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -888,16 +888,16 @@ static int hpage_collapse_find_target_node(struct collapse_control *cc)
>  }
>  #endif
>
> -static bool hpage_collapse_alloc_page(struct page **hpage, gfp_t gfp, int node,
> +static bool hpage_collapse_alloc_folio(struct folio **folio, gfp_t gfp, int node,
>                                       nodemask_t *nmask)
>  {
> -       *hpage = __alloc_pages(gfp, HPAGE_PMD_ORDER, node, nmask);
> -       if (unlikely(!*hpage)) {
> +       *folio = __folio_alloc(gfp, HPAGE_PMD_ORDER, node, nmask);
> +
> +       if (unlikely(!*folio)) {
>                 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
>                 return false;
>         }
>
> -       folio_prep_large_rmappable((struct folio *)*hpage);
>         count_vm_event(THP_COLLAPSE_ALLOC);
>         return true;
>  }
> @@ -1064,17 +1064,20 @@ static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm,
>         int node = hpage_collapse_find_target_node(cc);
>         struct folio *folio;
>
> -       if (!hpage_collapse_alloc_page(hpage, gfp, node, &cc->alloc_nmask))
> +       if (!hpage_collapse_alloc_folio(&folio, gfp, node, &cc->alloc_nmask)) {
> +               *hpage = NULL;
>                 return SCAN_ALLOC_HUGE_PAGE_FAIL;
> +       }
>
> -       folio = page_folio(*hpage);
>         if (unlikely(mem_cgroup_charge(folio, mm, gfp))) {
>                 folio_put(folio);
>                 *hpage = NULL;
>                 return SCAN_CGROUP_CHARGE_FAIL;
>         }
> -       count_memcg_page_event(*hpage, THP_COLLAPSE_ALLOC);
>
> +       count_memcg_folio_events(folio, THP_COLLAPSE_ALLOC, 1);
> +
> +       *hpage = folio_page(folio, 0);
>         return SCAN_SUCCEED;
>  }
>
> --
> 2.40.1
>