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

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Date:   Sat, 13 Mar 2021 20:03:59 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Miaohe Lin <linmiaohe@...wei.com>
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()

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.

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