2021-02-02 09:59:25

by Xu, Yanfei

Subject: [PATCH] mm/hugetlb: remove a meaningless if statement in gigantic page initialization

From: Yanfei Xu <[email protected]>

Gigantic page is a compound page and its order is more than 1.
Thus it must be available for hpage_pincount. Let's remove this
meaningless if statement.

Signed-off-by: Yanfei Xu <[email protected]>
---
mm/hugetlb.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a3e4fa2c5e94..73d602f8c7e2 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1501,9 +1501,7 @@ static void prep_compound_gigantic_page(struct page *page, unsigned int order)
set_compound_head(p, page);
}
atomic_set(compound_mapcount_ptr(page), -1);
-
- if (hpage_pincount_available(page))
- atomic_set(compound_pincount_ptr(page), 0);
+ atomic_set(compound_pincount_ptr(page), 0);
}

/*
--
2.27.0

2021-02-02 10:12:33

by David Hildenbrand

Subject: Re: [PATCH] mm/hugetlb: remove a meaningless if statement in gigantic page initialization

On 02.02.21 11:12, [email protected] wrote:
> From: Yanfei Xu <[email protected]>
>
> Gigantic page is a compound page and its order is more than 1.
> Thus it must be available for hpage_pincount. Let's remove this
> meaningless if statement.
>
> Signed-off-by: Yanfei Xu <[email protected]>
> ---
> mm/hugetlb.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index a3e4fa2c5e94..73d602f8c7e2 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1501,9 +1501,7 @@ static void prep_compound_gigantic_page(struct page *page, unsigned int order)
> set_compound_head(p, page);
> }
> atomic_set(compound_mapcount_ptr(page), -1);
> -
> - if (hpage_pincount_available(page))
> - atomic_set(compound_pincount_ptr(page), 0);
> + atomic_set(compound_pincount_ptr(page), 0);
> }
>
> /*
>

I can spot similar handling in destroy_compound_gigantic_page(). If this
is correct (which I think it is), we should tackle both occurrences at once.

--
Thanks,

David / dhildenb

2021-02-02 10:24:14

by Xu, Yanfei

Subject: Re: [PATCH] mm/hugetlb: remove a meaningless if statement in gigantic page initialization

On 2/2/21 6:06 PM, David Hildenbrand wrote:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
>
> On 02.02.21 11:12, [email protected] wrote:
>> From: Yanfei Xu <[email protected]>
>>
>> Gigantic page is a compound page and its order is more than 1.
>> Thus it must be available for hpage_pincount. Let's remove this
>> meaningless if statement.
>>
>> Signed-off-by: Yanfei Xu <[email protected]>
>> ---
>>   mm/hugetlb.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index a3e4fa2c5e94..73d602f8c7e2 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -1501,9 +1501,7 @@ static void prep_compound_gigantic_page(struct
>> page *page, unsigned int order)
>>               set_compound_head(p, page);
>>       }
>>       atomic_set(compound_mapcount_ptr(page), -1);
>> -
>> -     if (hpage_pincount_available(page))
>> -             atomic_set(compound_pincount_ptr(page), 0);
>> +     atomic_set(compound_pincount_ptr(page), 0);
>>   }
>>
>>   /*
>>
>
> I can spot similar handling in destroy_compound_gigantic_page(). If this
> is correct (which I think it is), we should tackle both occurrences at
> once.
>
Agree. Will do it in v2.

Thanks,
Yanfei
> --
> Thanks,
>
> David / dhildenb
>