diff mbox series

[v2,4/4] mm/memory: convert do_read_fault() to use folios

Message ID 20230705194335.273790-4-sidhartha.kumar@oracle.com
State New
Headers
Series [v2,1/4] mm/memory: convert do_page_mkwrite() to use folios |

Commit Message

Sidhartha Kumar July 5, 2023, 7:43 p.m. UTC 
  Saves one implicit call to compound_head()

Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
---
v2
	 - move folio initialization after __do_fault()

 mm/memory.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Comments

Matthew Wilcox July 5, 2023, 8:19 p.m. UTC | #1 
On Wed, Jul 05, 2023 at 12:43:35PM -0700, Sidhartha Kumar wrote:
> Saves one implicit call to compound_head()
> 
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>

> @@ -4543,10 +4544,12 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf)
>  	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
>  		return ret;
>  
> +	folio = page_folio(vmf->page);

Why not move this down to after the call to finish_fault()?  The
compiler should be able to do a better job with that; it may have to
spill it to the stack to preserve it over the function call.

>  	ret |= finish_fault(vmf);
> -	unlock_page(vmf->page);
> +	folio_unlock(folio);
>  	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
> -		put_page(vmf->page);
> +		folio_put(folio);
>  	return ret;
Sidhartha Kumar July 5, 2023, 8:25 p.m. UTC | #2 
On 7/5/23 1:19 PM, Matthew Wilcox wrote:
> On Wed, Jul 05, 2023 at 12:43:35PM -0700, Sidhartha Kumar wrote:
>> Saves one implicit call to compound_head()
>>
>> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> 
> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> 
>> @@ -4543,10 +4544,12 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf)
>>   	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
>>   		return ret;
>>   
>> +	folio = page_folio(vmf->page);
> 
> Why not move this down to after the call to finish_fault()?  The
> compiler should be able to do a better job with that; it may have to
> spill it to the stack to preserve it over the function call.
> 

I just noticed that the page inside the vmf was being used in 
finish_fault() so it would stable enough to do the folio conversion 
before. I can move it after for compiler reasons.

>>   	ret |= finish_fault(vmf);
>> -	unlock_page(vmf->page);
>> +	folio_unlock(folio);
>>   	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
>> -		put_page(vmf->page);
>> +		folio_put(folio);
>>   	return ret;
> 
>
diff mbox series

Patch

diff --git a/mm/memory.c b/mm/memory.c
index ce7826d3f6200..e40a03e488ca2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4527,6 +4527,7 @@  static inline bool should_fault_around(struct vm_fault *vmf)
 static vm_fault_t do_read_fault(struct vm_fault *vmf)
 {
 	vm_fault_t ret = 0;
+	struct folio *folio;
 
 	/*
 	 * Let's call ->map_pages() first and use ->fault() as fallback
@@ -4543,10 +4544,12 @@  static vm_fault_t do_read_fault(struct vm_fault *vmf)
 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
 		return ret;
 
+	folio = page_folio(vmf->page);
+
 	ret |= finish_fault(vmf);
-	unlock_page(vmf->page);
+	folio_unlock(folio);
 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
-		put_page(vmf->page);
+		folio_put(folio);
 	return ret;
 }