* [PATCH] mm: Remove redundant PageMemcgKmem(page) call
@ 2025-02-12 2:06 Shengken Lin
2025-02-12 4:28 ` Matthew Wilcox
0 siblings, 1 reply; 4+ messages in thread
From: Shengken Lin @ 2025-02-12 2:06 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel, Shengken Lin
The function of PageMemcgKmem(page) is the same as that of
folio_memcg_kmem(folio).
Since __memcg_kmem_uncharge_page already uses folio_memcg_kmem to check
if a folio has been uncharged, calling PageMemcgKmem(page) before
__memcg_kmem_uncharge_page is redundant.
Signed-off-by: Shengken Lin <shengken.lin@amlogic.com>
---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 579789600a3c..5a76760de495 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1055,7 +1055,7 @@ __always_inline bool free_pages_prepare(struct page *page,
trace_mm_page_free(page, order);
kmsan_free_page(page, order);
- if (memcg_kmem_online() && PageMemcgKmem(page))
+ if (memcg_kmem_online())
__memcg_kmem_uncharge_page(page, order);
/*
--
2.34.1
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm: Remove redundant PageMemcgKmem(page) call
2025-02-12 2:06 [PATCH] mm: Remove redundant PageMemcgKmem(page) call Shengken Lin
@ 2025-02-12 4:28 ` Matthew Wilcox
2025-02-20 9:47 ` Shengken.Lin
0 siblings, 1 reply; 4+ messages in thread
From: Matthew Wilcox @ 2025-02-12 4:28 UTC (permalink / raw)
To: Shengken Lin; +Cc: akpm, linux-mm, linux-kernel
On Wed, Feb 12, 2025 at 10:06:27AM +0800, Shengken Lin wrote:
> The function of PageMemcgKmem(page) is the same as that of
> folio_memcg_kmem(folio).
>
> Since __memcg_kmem_uncharge_page already uses folio_memcg_kmem to check
> if a folio has been uncharged, calling PageMemcgKmem(page) before
> __memcg_kmem_uncharge_page is redundant.
But it saves a function call. NAK.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Re: [PATCH] mm: Remove redundant PageMemcgKmem(page) call
2025-02-12 4:28 ` Matthew Wilcox
@ 2025-02-20 9:47 ` Shengken.Lin
2025-02-20 13:22 ` Matthew Wilcox
0 siblings, 1 reply; 4+ messages in thread
From: Shengken.Lin @ 2025-02-20 9:47 UTC (permalink / raw)
To: Matthew Wilcox; +Cc: akpm, linux-mm, linux-kernel
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On Wed, 12 Feb 2025 04:28PM +0000, Matthew Wilcox wrote:
>On Wed, Feb 12, 2025 at 10:06:27AM +0800, Shengken Lin wrote:
>> The function of PageMemcgKmem(page) is the same as that of
>> folio_memcg_kmem(folio).
>>
>> Since __memcg_kmem_uncharge_page already uses folio_memcg_kmem to check
>> if a folio has been uncharged, calling PageMemcgKmem(page) before
>> __memcg_kmem_uncharge_page is redundant.
>
>But it saves a function call. NAK.
Hi Matthew Wilcox,
If it can save a function call, then adding PageMemcgKmem(page)
in include/linux/memcontrol.h would make the code more consistent.
If this is considered more reasonable, I can submit a new patch.
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1707,7 +1707,7 @@ static inline int memcg_kmem_charge_page(struct page *page, gfp_t gfp,
static inline void memcg_kmem_uncharge_page(struct page *page, int order)
{
- if (memcg_kmem_online())
+ if (memcg_kmem_online() && PageMemcgKmem(page))
__memcg_kmem_uncharge_page(page, order);
}
--
Best regards,
Shengken Lin
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2025-02-12 2:06 [PATCH] mm: Remove redundant PageMemcgKmem(page) call Shengken Lin
2025-02-12 4:28 ` Matthew Wilcox
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2025-02-20 13:22 ` Matthew Wilcox
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