linux-kernel - Re: [PATCH 1/2] arm64/hugetlb: Use ptep_get() to get the pte value of a huge page

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Message-ID: <278d1d30-a7ad-11df-5242-5472a841a3b3@linux.alibaba.com>
Date:   Wed, 11 May 2022 09:24:09 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     Muchun Song <songmuchun@...edance.com>
Cc:     catalin.marinas@....com, will@...nel.org, mike.kravetz@...cle.com,
        akpm@...ux-foundation.org, willy@...radead.org,
        anshuman.khandual@....com, christophe.leroy@...roup.eu,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH 1/2] arm64/hugetlb: Use ptep_get() to get the pte value of
 a huge page



On 5/10/2022 11:55 PM, Muchun Song wrote:
> On Tue, May 10, 2022 at 07:12:52PM +0800, Baolin Wang wrote:
>> The original huge_ptep_get() on ARM64 is just a wrapper of ptep_get(),
>> which will not take into account any contig-PTEs dirty and access bits.
>> Meanwhile we will implement a new ARM64-specific huge_ptep_get()
>> interface in following patch, which will take into account any contig-PTEs
>> dirty and access bits and only be allowed to pass the head pte of
>> a contig-PTE/PMD size page.
> 
> IIUC, the huge_ptep_get() you have implemented in patch 2 could
> handle non-head pte. It'll return the original pte without potential
> AD bit. I admit it is more efficeent to use ptep_get() directly,
> but the judgement here should be updated.

Ah, right. I missed the 'ncontig' will be 0 if a non-head pte passed. 
Will update the commit message in next version. Thanks for reviewing.

> 
> With this update.
> 
> Reviewed-by: Muchun Song <songmuchun@...edance.com>