linux-kernel - Re: [PATCH v3 2/5] mm/khugepaged: Convert hpage_collapse_scan

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Message-ID: <CAHbLzkpPM=21+7j6ADxXWcUe0Hp3n2aJP2fepE4DrFY6jr6=iA@mail.gmail.com>
Date:   Tue, 24 Oct 2023 10:38:26 -0700
From:   Yang Shi <shy828301@...il.com>
To:     "Vishal Moola (Oracle)" <vishal.moola@...il.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org
Subject: Re: [PATCH v3 2/5] mm/khugepaged: Convert hpage_collapse_scan_pmd()
 to use folios

On Fri, Oct 20, 2023 at 11:34 AM Vishal Moola (Oracle)
<vishal.moola@...il.com> wrote:
>
> Replaces 5 calls to compound_head(), and removes 1385 bytes of kernel
> text.
>
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>

Reviewed-by: Yang Shi <shy828301@...il.com>

> ---
>  mm/khugepaged.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 500756604488..6c4b5af43371 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1248,6 +1248,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
>         int result = SCAN_FAIL, referenced = 0;
>         int none_or_zero = 0, shared = 0;
>         struct page *page = NULL;
> +       struct folio *folio = NULL;
>         unsigned long _address;
>         spinlock_t *ptl;
>         int node = NUMA_NO_NODE, unmapped = 0;
> @@ -1334,29 +1335,28 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
>                         }
>                 }
>
> -               page = compound_head(page);
> -
> +               folio = page_folio(page);
>                 /*
>                  * Record which node the original page is from and save this
>                  * information to cc->node_load[].
>                  * Khugepaged will allocate hugepage from the node has the max
>                  * hit record.
>                  */
> -               node = page_to_nid(page);
> +               node = folio_nid(folio);
>                 if (hpage_collapse_scan_abort(node, cc)) {
>                         result = SCAN_SCAN_ABORT;
>                         goto out_unmap;
>                 }
>                 cc->node_load[node]++;
> -               if (!PageLRU(page)) {
> +               if (!folio_test_lru(folio)) {
>                         result = SCAN_PAGE_LRU;
>                         goto out_unmap;
>                 }
> -               if (PageLocked(page)) {
> +               if (folio_test_locked(folio)) {
>                         result = SCAN_PAGE_LOCK;
>                         goto out_unmap;
>                 }
> -               if (!PageAnon(page)) {
> +               if (!folio_test_anon(folio)) {
>                         result = SCAN_PAGE_ANON;
>                         goto out_unmap;
>                 }
> @@ -1371,7 +1371,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
>                  * has excessive GUP pins (i.e. 512).  Anyway the same check
>                  * will be done again later the risk seems low.
>                  */
> -               if (!is_refcount_suitable(page)) {
> +               if (!is_refcount_suitable(&folio->page)) {
>                         result = SCAN_PAGE_COUNT;
>                         goto out_unmap;
>                 }
> @@ -1381,8 +1381,8 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
>                  * enough young pte to justify collapsing the page
>                  */
>                 if (cc->is_khugepaged &&
> -                   (pte_young(pteval) || page_is_young(page) ||
> -                    PageReferenced(page) || mmu_notifier_test_young(vma->vm_mm,
> +                   (pte_young(pteval) || folio_test_young(folio) ||
> +                    folio_test_referenced(folio) || mmu_notifier_test_young(vma->vm_mm,
>                                                                      address)))
>                         referenced++;
>         }
> @@ -1404,7 +1404,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
>                 *mmap_locked = false;
>         }
>  out:
> -       trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
> +       trace_mm_khugepaged_scan_pmd(mm, &folio->page, writable, referenced,
>                                      none_or_zero, result, unmapped);
>         return result;
>  }
> --
> 2.40.1
>