linux-kernel - Re: [PATCH] mm/huge_memory: remove unneeded local variable follflags

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Date:   Fri, 11 Mar 2022 14:26:30 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Anshuman Khandual <anshuman.khandual@....com>,
        <akpm@...ux-foundation.org>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/huge_memory: remove unneeded local variable follflags

On 2022/3/11 12:51, Anshuman Khandual wrote:
> Hi Miaohe,
> 
> On 3/10/22 18:42, Miaohe Lin wrote:
>> We can pass FOLL_GET | FOLL_DUMP to follow_page directly to simplify
>> the code a bit.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
>> ---
>>  mm/huge_memory.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index 3557aabe86fe..418d077da246 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -2838,7 +2838,6 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
>>  	 */
>>  	for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
>>  		struct vm_area_struct *vma = find_vma(mm, addr);
>> -		unsigned int follflags;
>>  		struct page *page;
>>  
>>  		if (!vma || addr < vma->vm_start)
>> @@ -2851,8 +2850,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
>>  		}
>>  
>>  		/* FOLL_DUMP to ignore special (like zero) pages */
>> -		follflags = FOLL_GET | FOLL_DUMP;
>> -		page = follow_page(vma, addr, follflags);
>> +		page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
>>  
>>  		if (IS_ERR(page))
>>  			continue;
> 
> LGTM, but there is another similar instance in add_page_for_migration()
> inside mm/migrate.c, requiring this exact clean up.
> 

Thanks for comment. That similar case is done in my previous patch series[1]
aimed at migration cleanup and fixup. It might be more suitable to do that
clean up in that specialized series?

[1]:https://lore.kernel.org/linux-mm/20220304093409.25829-4-linmiaohe@huawei.com/

> Hence with that change in place.
> 
> Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>

Thanks again.

> .
>