linux-kernel - Re: [PATCH 1/6] mm/huge_memory.c: rework the function vma_adjust_trans

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Date:   Mon, 15 Mar 2021 10:04:23 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Matthew Wilcox <willy@...radead.org>
CC:     <akpm@...ux-foundation.org>, <ziy@...dia.com>,
        <william.kucharski@...cle.com>, <vbabka@...e.cz>,
        <richard.weiyang@...ux.alibaba.com>, <peterx@...hat.com>,
        <anshuman.khandual@....com>, <thomas_os@...pmail.org>,
        <rcampbell@...dia.com>, <aneesh.kumar@...ux.ibm.com>,
        <yang.shi@...ux.alibaba.com>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>
Subject: Re: [PATCH 1/6] mm/huge_memory.c: rework the function
 vma_adjust_trans_huge()

Hi:
On 2021/3/14 4:03, Matthew Wilcox wrote:
> On Sat, Mar 13, 2021 at 05:32:19AM -0500, Miaohe Lin wrote:
>> +static inline void try_to_split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address)
>> +{
>> +	if (address & ~HPAGE_PMD_MASK &&
>> +	    range_in_vma(vma, address & HPAGE_PMD_MASK,
>> +			 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE))
>> +		split_huge_pmd_address(vma, address, false, NULL);
>> +}
> 
> This isn't "try to split".  This is "split if needed".  I think the
> comments also need to be moved up here.
> 

Make sense. Would do it in v2! Thanks!

> I'm not even sure this is really an improvement.
> .
> 

At least we can eliminate a couple of duplicated lines and use helper range_in_vma() to improve
the readability slightly. Right? :)