2023-10-20 18:34:04

by Vishal Moola

[permalink] [raw]
Subject: [PATCH v3 3/5] mm/khugepaged: Convert is_refcount_suitable() to use folios

Both callers of is_refcount_suitable() have been converted to use
folios, so convert it to take in a folio. Both callers only operate on
head pages of folios so mapcount/refcount conversions here are trivial.

Removes 3 calls to compound head, and removes 315 bytes of kernel text.

Signed-off-by: Vishal Moola (Oracle) <[email protected]>
---
mm/khugepaged.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 6c4b5af43371..9efd8ff68f06 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -524,15 +524,15 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte,
}
}

-static bool is_refcount_suitable(struct page *page)
+static bool is_refcount_suitable(struct folio *folio)
{
int expected_refcount;

- expected_refcount = total_mapcount(page);
- if (PageSwapCache(page))
- expected_refcount += compound_nr(page);
+ expected_refcount = folio_mapcount(folio);
+ if (folio_test_swapcache(folio))
+ expected_refcount += folio_nr_pages(folio);

- return page_count(page) == expected_refcount;
+ return folio_ref_count(folio) == expected_refcount;
}

static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
@@ -625,7 +625,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
* but not from this process. The other process cannot write to
* the page, only trigger CoW.
*/
- if (!is_refcount_suitable(&folio->page)) {
+ if (!is_refcount_suitable(folio)) {
folio_unlock(folio);
result = SCAN_PAGE_COUNT;
goto out;
@@ -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(&folio->page)) {
+ if (!is_refcount_suitable(folio)) {
result = SCAN_PAGE_COUNT;
goto out_unmap;
}
--
2.40.1


2023-10-23 07:06:22

by David Hildenbrand

[permalink] [raw]
Subject: Re: [PATCH v3 3/5] mm/khugepaged: Convert is_refcount_suitable() to use folios

On 20.10.23 20:33, Vishal Moola (Oracle) wrote:
> Both callers of is_refcount_suitable() have been converted to use
> folios, so convert it to take in a folio. Both callers only operate on
> head pages of folios so mapcount/refcount conversions here are trivial.
>
> Removes 3 calls to compound head, and removes 315 bytes of kernel text.
>
> Signed-off-by: Vishal Moola (Oracle) <[email protected]>
> ---
> mm/khugepaged.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 6c4b5af43371..9efd8ff68f06 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -524,15 +524,15 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte,
> }
> }
>
> -static bool is_refcount_suitable(struct page *page)
> +static bool is_refcount_suitable(struct folio *folio)
> {
> int expected_refcount;
>
> - expected_refcount = total_mapcount(page);
> - if (PageSwapCache(page))
> - expected_refcount += compound_nr(page);
> + expected_refcount = folio_mapcount(folio);
> + if (folio_test_swapcache(folio))
> + expected_refcount += folio_nr_pages(folio);
>
> - return page_count(page) == expected_refcount;
> + return folio_ref_count(folio) == expected_refcount;
> }
>
> static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
> @@ -625,7 +625,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
> * but not from this process. The other process cannot write to
> * the page, only trigger CoW.
> */
> - if (!is_refcount_suitable(&folio->page)) {
> + if (!is_refcount_suitable(folio)) {
> folio_unlock(folio);
> result = SCAN_PAGE_COUNT;
> goto out;
> @@ -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(&folio->page)) {
> + if (!is_refcount_suitable(folio)) {
> result = SCAN_PAGE_COUNT;
> goto out_unmap;
> }

Reviewed-by: David Hildenbrand <[email protected]>

--
Cheers,

David / dhildenb

2023-10-24 17:39:28

by Yang Shi

[permalink] [raw]
Subject: Re: [PATCH v3 3/5] mm/khugepaged: Convert is_refcount_suitable() to use folios

On Fri, Oct 20, 2023 at 11:34 AM Vishal Moola (Oracle)
<[email protected]> wrote:
>
> Both callers of is_refcount_suitable() have been converted to use
> folios, so convert it to take in a folio. Both callers only operate on
> head pages of folios so mapcount/refcount conversions here are trivial.
>
> Removes 3 calls to compound head, and removes 315 bytes of kernel text.
>
> Signed-off-by: Vishal Moola (Oracle) <[email protected]>

Reviewed-by: Yang Shi <[email protected]>

> ---
> mm/khugepaged.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 6c4b5af43371..9efd8ff68f06 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -524,15 +524,15 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte,
> }
> }
>
> -static bool is_refcount_suitable(struct page *page)
> +static bool is_refcount_suitable(struct folio *folio)
> {
> int expected_refcount;
>
> - expected_refcount = total_mapcount(page);
> - if (PageSwapCache(page))
> - expected_refcount += compound_nr(page);
> + expected_refcount = folio_mapcount(folio);
> + if (folio_test_swapcache(folio))
> + expected_refcount += folio_nr_pages(folio);
>
> - return page_count(page) == expected_refcount;
> + return folio_ref_count(folio) == expected_refcount;
> }
>
> static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
> @@ -625,7 +625,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
> * but not from this process. The other process cannot write to
> * the page, only trigger CoW.
> */
> - if (!is_refcount_suitable(&folio->page)) {
> + if (!is_refcount_suitable(folio)) {
> folio_unlock(folio);
> result = SCAN_PAGE_COUNT;
> goto out;
> @@ -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(&folio->page)) {
> + if (!is_refcount_suitable(folio)) {
> result = SCAN_PAGE_COUNT;
> goto out_unmap;
> }
> --
> 2.40.1
>
>