2022-01-10 04:24:27

by Matthew Wilcox

Subject: [PATCH v2 14/28] mm: Convert page_maybe_dma_pinned() to use a folio

Replace three calls to compound_head() with one. This removes the last
user of compound_pincount(), so remove that helper too.

Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
---
include/linux/mm.h | 21 ++++++++-------------
1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index bf9624ca61c3..d3769897c8ac 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -934,13 +934,6 @@ static inline int head_compound_pincount(struct page *head)
return atomic_read(compound_pincount_ptr(head));
}

-static inline int compound_pincount(struct page *page)
-{
- VM_BUG_ON_PAGE(!PageCompound(page), page);
- page = compound_head(page);
- return head_compound_pincount(page);
-}
-
static inline void set_compound_order(struct page *page, unsigned int order)
{
page[1].compound_order = order;
@@ -1340,18 +1333,20 @@ void unpin_user_pages(struct page **pages, unsigned long npages);
*/
static inline bool page_maybe_dma_pinned(struct page *page)
{
- if (PageCompound(page))
- return compound_pincount(page) > 0;
+ struct folio *folio = page_folio(page);
+
+ if (folio_test_large(folio))
+ return atomic_read(folio_pincount_ptr(folio)) > 0;

/*
- * page_ref_count() is signed. If that refcount overflows, then
- * page_ref_count() returns a negative value, and callers will avoid
+ * folio_ref_count() is signed. If that refcount overflows, then
+ * folio_ref_count() returns a negative value, and callers will avoid
* further incrementing the refcount.
*
- * Here, for that overflow case, use the signed bit to count a little
+ * Here, for that overflow case, use the sign bit to count a little
* bit higher via unsigned math, and thus still get an accurate result.
*/
- return ((unsigned int)page_ref_count(compound_head(page))) >=
+ return ((unsigned int)folio_ref_count(folio)) >=
GUP_PIN_COUNTING_BIAS;
}

--
2.33.0

2022-01-10 08:35:12

by Christoph Hellwig

Subject: Re: [PATCH v2 14/28] mm: Convert page_maybe_dma_pinned() to use a folio

On Mon, Jan 10, 2022 at 04:23:52AM +0000, Matthew Wilcox (Oracle) wrote:
> Replace three calls to compound_head() with one. This removes the last
> user of compound_pincount(), so remove that helper too.

Looks good,

Reviewed-by: Christoph Hellwig <[email protected]>

2022-01-11 04:27:24

by John Hubbard

Subject: Re: [PATCH v2 14/28] mm: Convert page_maybe_dma_pinned() to use a folio

On 1/9/22 20:23, Matthew Wilcox (Oracle) wrote:
> Replace three calls to compound_head() with one. This removes the last
> user of compound_pincount(), so remove that helper too.
>
> Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
> ---
> include/linux/mm.h | 21 ++++++++-------------
> 1 file changed, 8 insertions(+), 13 deletions(-)

Reviewed-by: John Hubbard <[email protected]>


thanks,
--
John Hubbard
NVIDIA

>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index bf9624ca61c3..d3769897c8ac 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -934,13 +934,6 @@ static inline int head_compound_pincount(struct page *head)
> return atomic_read(compound_pincount_ptr(head));
> }
>
> -static inline int compound_pincount(struct page *page)
> -{
> - VM_BUG_ON_PAGE(!PageCompound(page), page);
> - page = compound_head(page);
> - return head_compound_pincount(page);
> -}
> -
> static inline void set_compound_order(struct page *page, unsigned int order)
> {
> page[1].compound_order = order;
> @@ -1340,18 +1333,20 @@ void unpin_user_pages(struct page **pages, unsigned long npages);
> */
> static inline bool page_maybe_dma_pinned(struct page *page)
> {
> - if (PageCompound(page))
> - return compound_pincount(page) > 0;
> + struct folio *folio = page_folio(page);
> +
> + if (folio_test_large(folio))
> + return atomic_read(folio_pincount_ptr(folio)) > 0;
>
> /*
> - * page_ref_count() is signed. If that refcount overflows, then
> - * page_ref_count() returns a negative value, and callers will avoid
> + * folio_ref_count() is signed. If that refcount overflows, then
> + * folio_ref_count() returns a negative value, and callers will avoid
> * further incrementing the refcount.
> *
> - * Here, for that overflow case, use the signed bit to count a little
> + * Here, for that overflow case, use the sign bit to count a little
> * bit higher via unsigned math, and thus still get an accurate result.
> */
> - return ((unsigned int)page_ref_count(compound_head(page))) >=
> + return ((unsigned int)folio_ref_count(folio)) >=
> GUP_PIN_COUNTING_BIAS;
> }
>