linux-kernel - Re: [PATCH v2 1/6] mm/huge_memory.c: rework the function vma_adjust_trans

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Message-ID: <20210317130706.GJ395976@xz-x1>
Date:   Wed, 17 Mar 2021 09:07:06 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     akpm@...ux-foundation.org, ziy@...dia.com, willy@...radead.org,
        william.kucharski@...cle.com, vbabka@...e.cz,
        yulei.kernel@...il.com, walken@...gle.com,
        aneesh.kumar@...ux.ibm.com, rcampbell@...dia.com,
        thomas_os@...pmail.org, yang.shi@...ux.alibaba.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v2 1/6] mm/huge_memory.c: rework the function
 vma_adjust_trans_huge()

On Wed, Mar 17, 2021 at 10:18:40AM +0800, Miaohe Lin wrote:
> Hi:
> On 2021/3/17 4:40, Peter Xu wrote:
> > On Tue, Mar 16, 2021 at 08:40:02AM -0400, Miaohe Lin wrote:
> >> +static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)
> >> +{
> >> +	/*
> >> +	 * If the new address isn't hpage aligned and it could previously
> >> +	 * contain an hugepage: check if we need to split an huge pmd.
> >> +	 */
> >> +	if (address & ~HPAGE_PMD_MASK &&
> >> +	    range_in_vma(vma, address & HPAGE_PMD_MASK,
> >> +			 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE))
> > 
> > Since you're at it, maybe use ALIGN/ALIGN_DOWN too against HPAGE_PMD_SIZE?
> > 
> 
> Many thanks for reply. Sounds good. :) Do you mean this?
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index bff92dea5ab3..ae16a82da823 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2301,44 +2301,38 @@ void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
>         __split_huge_pmd(vma, pmd, address, freeze, page);
>  }
> 
> +static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)
> +{
> +       /*
> +        * If the new address isn't hpage aligned and it could previously
> +        * contain an hugepage: check if we need to split an huge pmd.
> +        */
> +       if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) &&
> +           range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE),
> +                        ALIGN(address, HPAGE_PMD_SIZE)))
> +               split_huge_pmd_address(vma, address, false, NULL);
> +}
> +

Yes. Thanks,

-- 
Peter Xu