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[PATCH] mm: huge_memory: add the missing folio_test_pmd_mappable() for THP split statistics

Baolin Wang posted 1 patch 1 year, 10 months ago
There is a newer version of this series
mm/huge_memory.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
[PATCH] mm: huge_memory: add the missing folio_test_pmd_mappable() for THP split statistics
Posted by Baolin Wang 1 year, 10 months ago 
Now the mTHP can also be split or added into the deferred list, so add
folio_test_pmd_mappable() validation for PMD mapped THP, to avoid confusion
with PMD mapped THP related statistics.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 mm/huge_memory.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1683de78c313..3ca9282a0dc9 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3109,7 +3109,8 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
 		i_mmap_unlock_read(mapping);
 out:
 	xas_destroy(&xas);
-	count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
+	if (folio_test_pmd_mappable(folio))
+		count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
 	return ret;
 }
 
@@ -3171,7 +3172,8 @@ void deferred_split_folio(struct folio *folio)
 
 	spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
 	if (list_empty(&folio->_deferred_list)) {
-		count_vm_event(THP_DEFERRED_SPLIT_PAGE);
+		if (folio_test_pmd_mappable(folio))
+			count_vm_event(THP_DEFERRED_SPLIT_PAGE);
 		list_add_tail(&folio->_deferred_list, &ds_queue->split_queue);
 		ds_queue->split_queue_len++;
 #ifdef CONFIG_MEMCG
-- 
2.39.3
Re: [PATCH] mm: huge_memory: add the missing folio_test_pmd_mappable() for THP split statistics
Posted by Lance Yang 1 year, 9 months ago 
Hey Baolin,

Maybe I spotted a bug and made a change to this patch as follows.

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 824eff9211db..f3c4e08c6d30 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2994,6 +2994,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
 	XA_STATE_ORDER(xas, &folio->mapping->i_pages, folio->index, new_order);
 	struct anon_vma *anon_vma = NULL;
 	struct address_space *mapping = NULL;
+	int order = folio_order(folio);
 	int extra_pins, ret;
 	pgoff_t end;
 	bool is_hzp;
@@ -3172,7 +3173,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
 		i_mmap_unlock_read(mapping);
 out:
 	xas_destroy(&xas);
-	if (folio_test_pmd_mappable(folio))

IIUC, if we split the folio successfully, it won’t be large here.

+	if (order >= HPAGE_PMD_ORDER)
 		count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
 	return ret;
 }

Thanks,
Lance
Re: [PATCH] mm: huge_memory: add the missing folio_test_pmd_mappable() for THP split statistics
Posted by Baolin Wang 1 year, 9 months ago 

On 2024/4/22 14:17, Lance Yang wrote:
> Hey Baolin,
> 
> Maybe I spotted a bug and made a change to this patch as follows.
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 824eff9211db..f3c4e08c6d30 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2994,6 +2994,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
>   	XA_STATE_ORDER(xas, &folio->mapping->i_pages, folio->index, new_order);
>   	struct anon_vma *anon_vma = NULL;
>   	struct address_space *mapping = NULL;
> +	int order = folio_order(folio);
>   	int extra_pins, ret;
>   	pgoff_t end;
>   	bool is_hzp;
> @@ -3172,7 +3173,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
>   		i_mmap_unlock_read(mapping);
>   out:
>   	xas_destroy(&xas);
> -	if (folio_test_pmd_mappable(folio))
> 
> IIUC, if we split the folio successfully, it won’t be large here.

Yes, good catch. I did a blindly copy-paste.

Will fix in next version. Thanks for reviewing.

> +	if (order >= HPAGE_PMD_ORDER)
>   		count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
>   	return ret;
>   }
> 
> Thanks,
> Lance
Re: [PATCH] mm: huge_memory: add the missing folio_test_pmd_mappable() for THP split statistics
Posted by David Hildenbrand 1 year, 10 months ago 
On 29.03.24 07:59, Baolin Wang wrote:
> Now the mTHP can also be split or added into the deferred list, so add
> folio_test_pmd_mappable() validation for PMD mapped THP, to avoid confusion
> with PMD mapped THP related statistics.
> 
> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> ---
>   mm/huge_memory.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 1683de78c313..3ca9282a0dc9 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -3109,7 +3109,8 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
>   		i_mmap_unlock_read(mapping);
>   out:
>   	xas_destroy(&xas);
> -	count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
> +	if (folio_test_pmd_mappable(folio))
> +		count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
>   	return ret;
>   }
>   
> @@ -3171,7 +3172,8 @@ void deferred_split_folio(struct folio *folio)
>   
>   	spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
>   	if (list_empty(&folio->_deferred_list)) {
> -		count_vm_event(THP_DEFERRED_SPLIT_PAGE);
> +		if (folio_test_pmd_mappable(folio))
> +			count_vm_event(THP_DEFERRED_SPLIT_PAGE);
>   		list_add_tail(&folio->_deferred_list, &ds_queue->split_queue);
>   		ds_queue->split_queue_len++;
>   #ifdef CONFIG_MEMCG

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb

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