linux-kernel - Re: [PATCH 1/6] mm: hugetlb_vmemmap: delete hugetlb_optimize_vmemmap

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Message-ID: <YrCm7fL59QOSPUSp@arm.com>
Date:   Mon, 20 Jun 2022 17:57:17 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Muchun Song <songmuchun@...edance.com>
Cc:     mike.kravetz@...cle.com, david@...hat.com,
        akpm@...ux-foundation.org, corbet@....net, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        Will Deacon <will@...nel.org>,
        Anshuman Khandual <anshuman.khandual@....com>
Subject: Re: [PATCH 1/6] mm: hugetlb_vmemmap: delete
 hugetlb_optimize_vmemmap_enabled()

On Mon, Jun 13, 2022 at 02:35:07PM +0800, Muchun Song wrote:
> The name hugetlb_optimize_vmemmap_enabled() a bit confusing as it tests
> two conditions (enabled and pages in use).  Instead of coming up to
> an appropriate name, we could just delete it.  There is already a
> discussion about deleting it in thread [1].
> 
> There is only one user of hugetlb_optimize_vmemmap_enabled() outside of
> hugetlb_vmemmap, that is flush_dcache_page() in arch/arm64/mm/flush.c.
> However, it does not need to call hugetlb_optimize_vmemmap_enabled()
> in flush_dcache_page() since HugeTLB pages are always fully mapped and
> only head page will be set PG_dcache_clean meaning only head page's flag
> may need to be cleared (see commit cf5a501d985b).  So it is easy to
> remove hugetlb_optimize_vmemmap_enabled().
> 
> Link: https://lore.kernel.org/all/c77c61c8-8a5a-87e8-db89-d04d8aaab4cc@oracle.com/ [1]
> Signed-off-by: Muchun Song <songmuchun@...edance.com>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> Cc: Anshuman Khandual <anshuman.khandual@....com>

Reviewed-by: Catalin Marinas <catalin.marinas@....com>