[PATCH] secretmem: Conert page_is_secretmem() to folio_is_secretmem()

[PATCH] secretmem: Conert page_is_secretmem() to folio_is_secretmem()

[Matthew Wilcox (Oracle)]

The only caller already has a folio, so use it to save calling
compound_head() in PageLRU() and remove a use of page->mapping.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/secretmem.h | 15 +++++++--------
 mm/gup.c                  |  2 +-
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
index 988528b5da43..6996f1f53f14 100644
--- a/include/linux/secretmem.h
+++ b/include/linux/secretmem.h
@@ -6,24 +6,23 @@
 
 extern const struct address_space_operations secretmem_aops;
 
-static inline bool page_is_secretmem(struct page *page)
+static inline bool folio_is_secretmem(struct folio *folio)
 {
 	struct address_space *mapping;
 
 	/*
-	 * Using page_mapping() is quite slow because of the actual call
-	 * instruction and repeated compound_head(page) inside the
-	 * page_mapping() function.
+	 * Using folio_mapping() is quite slow because of the actual call
+	 * instruction.
 	 * We know that secretmem pages are not compound and LRU so we can
 	 * save a couple of cycles here.
 	 */
-	if (PageCompound(page) || !PageLRU(page))
+	if (folio_test_large(folio) || folio_test_lru(folio))
 		return false;
 
 	mapping = (struct address_space *)
-		((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
+		((unsigned long)folio->mapping & ~PAGE_MAPPING_FLAGS);
 
-	if (!mapping || mapping != page->mapping)
+	if (!mapping || mapping != folio->mapping)
 		return false;
 
 	return mapping->a_ops == &secretmem_aops;
@@ -39,7 +38,7 @@ static inline bool vma_is_secretmem(struct vm_area_struct *vma)
 	return false;
 }
 
-static inline bool page_is_secretmem(struct page *page)
+static inline bool folio_is_secretmem(struct folio *folio)
 {
 	return false;
 }
diff --git a/mm/gup.c b/mm/gup.c
index 6d0c24e93425..2f8a2d89fde1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2600,7 +2600,7 @@ static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
 		if (!folio)
 			goto pte_unmap;
 
-		if (unlikely(page_is_secretmem(page))) {
+		if (unlikely(folio_is_secretmem(folio))) {
 			gup_put_folio(folio, 1, flags);
 			goto pte_unmap;
 		}
-- 
2.40.1

Re: [PATCH] secretmem: Conert page_is_secretmem() to folio_is_secretmem()

[Mike Rapoport]

On Mon, Aug 21, 2023 at 03:17:28PM +0100, Matthew Wilcox (Oracle) wrote:
> The only caller already has a folio, so use it to save calling
> compound_head() in PageLRU() and remove a use of page->mapping.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>

> ---
>  include/linux/secretmem.h | 15 +++++++--------
>  mm/gup.c                  |  2 +-
>  2 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
> index 988528b5da43..6996f1f53f14 100644
> --- a/include/linux/secretmem.h
> +++ b/include/linux/secretmem.h
> @@ -6,24 +6,23 @@
>  
>  extern const struct address_space_operations secretmem_aops;
>  
> -static inline bool page_is_secretmem(struct page *page)
> +static inline bool folio_is_secretmem(struct folio *folio)
>  {
>  	struct address_space *mapping;
>  
>  	/*
> -	 * Using page_mapping() is quite slow because of the actual call
> -	 * instruction and repeated compound_head(page) inside the
> -	 * page_mapping() function.
> +	 * Using folio_mapping() is quite slow because of the actual call
> +	 * instruction.
>  	 * We know that secretmem pages are not compound and LRU so we can
>  	 * save a couple of cycles here.
>  	 */
> -	if (PageCompound(page) || !PageLRU(page))
> +	if (folio_test_large(folio) || folio_test_lru(folio))
>  		return false;
>  
>  	mapping = (struct address_space *)
> -		((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
> +		((unsigned long)folio->mapping & ~PAGE_MAPPING_FLAGS);
>  
> -	if (!mapping || mapping != page->mapping)
> +	if (!mapping || mapping != folio->mapping)
>  		return false;
>  
>  	return mapping->a_ops == &secretmem_aops;
> @@ -39,7 +38,7 @@ static inline bool vma_is_secretmem(struct vm_area_struct *vma)
>  	return false;
>  }
>  
> -static inline bool page_is_secretmem(struct page *page)
> +static inline bool folio_is_secretmem(struct folio *folio)
>  {
>  	return false;
>  }
> diff --git a/mm/gup.c b/mm/gup.c
> index 6d0c24e93425..2f8a2d89fde1 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -2600,7 +2600,7 @@ static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
>  		if (!folio)
>  			goto pte_unmap;
>  
> -		if (unlikely(page_is_secretmem(page))) {
> +		if (unlikely(folio_is_secretmem(folio))) {
>  			gup_put_folio(folio, 1, flags);
>  			goto pte_unmap;
>  		}
> -- 
> 2.40.1
> 
> 

-- 
Sincerely yours,
Mike.

Re: [PATCH] secretmem: Conert page_is_secretmem() to folio_is_secretmem()

[David Hildenbrand]

On 21.08.23 16:17, Matthew Wilcox (Oracle) wrote:
> The only caller already has a folio, so use it to save calling
> compound_head() in PageLRU() and remove a use of page->mapping.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>   include/linux/secretmem.h | 15 +++++++--------
>   mm/gup.c                  |  2 +-
>   2 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
> index 988528b5da43..6996f1f53f14 100644
> --- a/include/linux/secretmem.h
> +++ b/include/linux/secretmem.h
> @@ -6,24 +6,23 @@
>   
>   extern const struct address_space_operations secretmem_aops;
>   
> -static inline bool page_is_secretmem(struct page *page)
> +static inline bool folio_is_secretmem(struct folio *folio)
>   {
>   	struct address_space *mapping;
>   
>   	/*
> -	 * Using page_mapping() is quite slow because of the actual call
> -	 * instruction and repeated compound_head(page) inside the
> -	 * page_mapping() function.
> +	 * Using folio_mapping() is quite slow because of the actual call
> +	 * instruction.
>   	 * We know that secretmem pages are not compound and LRU so we can
>   	 * save a couple of cycles here.
>   	 */
> -	if (PageCompound(page) || !PageLRU(page))
> +	if (folio_test_large(folio) || folio_test_lru(folio))
>   		return false;

You converted a "!PageLRU(page)" into a "folio_test_lru(folio)".

Shouldn't that be a "!folio_test_lru(folio)" ?

-- 
Cheers,

David / dhildenb

Re: [PATCH] secretmem: Conert page_is_secretmem() to folio_is_secretmem()

[Matthew Wilcox]

On Mon, Aug 21, 2023 at 05:32:50PM +0200, David Hildenbrand wrote:
> > -	if (PageCompound(page) || !PageLRU(page))
> > +	if (folio_test_large(folio) || folio_test_lru(folio))
> >   		return false;
> 
> You converted a "!PageLRU(page)" into a "folio_test_lru(folio)".
> 
> Shouldn't that be a "!folio_test_lru(folio)" ?

Well, that's embarrassing.  Obviously I don't have any secretmem
hardware, so my smoke-test didn't catch it.  Thanks, will do a v2.

Re: [PATCH] secretmem: Conert page_is_secretmem() to folio_is_secretmem()

[David Hildenbrand]

On 21.08.23 17:53, Matthew Wilcox wrote:
> On Mon, Aug 21, 2023 at 05:32:50PM +0200, David Hildenbrand wrote:
>>> -	if (PageCompound(page) || !PageLRU(page))
>>> +	if (folio_test_large(folio) || folio_test_lru(folio))
>>>    		return false;
>>
>> You converted a "!PageLRU(page)" into a "folio_test_lru(folio)".
>>
>> Shouldn't that be a "!folio_test_lru(folio)" ?
> 
> Well, that's embarrassing.  Obviously I don't have any secretmem
> hardware, so my smoke-test didn't catch it.  Thanks, will do a v2.
> 

We do have a selftest:

tools/testing/selftests/mm/memfd_secret.c

I doubt it would have caught it, because ptrace doesn't use GUP-fast 
IIRC, so we always fail early in GUP code when doing the 
vma_is_secretmem() check.

We'd explicitly have to call something that triggers GUP-fast 
(get_user_pages_fast/pin_user_pages_fast).

-- 
Cheers,

David / dhildenb