linux-kernel - Re: [PATCH V3 5/5] arm64/mm: Enable HugeTLB migration for contiguous bit HugeTLB pages

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Message-ID: <20181108103616.22z3imossjb5ffkw@capper-debian.cambridge.arm.com>
Date:   Thu, 8 Nov 2018 10:36:27 +0000
From:   Steve Capper <Steve.Capper@....com>
To:     Anshuman Khandual <Anshuman.Khandual@....com>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Suzuki Poulose <Suzuki.Poulose@....com>,
        Punit Agrawal <Punit.Agrawal@....com>,
        Will Deacon <Will.Deacon@....com>,
        Steven Price <Steven.Price@....com>,
        Catalin Marinas <Catalin.Marinas@....com>,
        "mhocko@...nel.org" <mhocko@...nel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "mike.kravetz@...cle.com" <mike.kravetz@...cle.com>,
        "n-horiguchi@...jp.nec.com" <n-horiguchi@...jp.nec.com>,
        nd <nd@....com>
Subject: Re: [PATCH V3 5/5] arm64/mm: Enable HugeTLB migration for contiguous
 bit HugeTLB pages

On Tue, Oct 23, 2018 at 06:32:01PM +0530, Anshuman Khandual wrote:
> Let arm64 subscribe to the previously added framework in which architecture
> can inform whether a given huge page size is supported for migration. This
> just overrides the default function arch_hugetlb_migration_supported() and
> enables migration for all possible HugeTLB page sizes on arm64. With this,
> HugeTLB migration support on arm64 now covers all possible HugeTLB options.
> 
>         CONT PTE    PMD    CONT PMD    PUD
>         --------    ---    --------    ---
> 4K:        64K      2M        32M      1G
> 16K:        2M     32M         1G
> 64K:        2M    512M        16G
> 
> Reviewed-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>

Reviewed-by: Steve Capper <steve.capper@....com>

> ---
>  arch/arm64/include/asm/hugetlb.h |  5 +++++
>  arch/arm64/mm/hugetlbpage.c      | 20 ++++++++++++++++++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
> index e73f685..656f70e 100644
> --- a/arch/arm64/include/asm/hugetlb.h
> +++ b/arch/arm64/include/asm/hugetlb.h
> @@ -20,6 +20,11 @@
>  
>  #include <asm/page.h>
>  
> +#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
> +#define arch_hugetlb_migration_supported arch_hugetlb_migration_supported
> +extern bool arch_hugetlb_migration_supported(struct hstate *h);
> +#endif
> +
>  static inline pte_t huge_ptep_get(pte_t *ptep)
>  {
>  	return READ_ONCE(*ptep);
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 21512ca..f3afdcf 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -27,6 +27,26 @@
>  #include <asm/tlbflush.h>
>  #include <asm/pgalloc.h>
>  
> +#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
> +bool arch_hugetlb_migration_supported(struct hstate *h)
> +{
> +	size_t pagesize = huge_page_size(h);
> +
> +	switch (pagesize) {
> +#ifdef CONFIG_ARM64_4K_PAGES
> +	case PUD_SIZE:
> +#endif
> +	case PMD_SIZE:
> +	case CONT_PMD_SIZE:
> +	case CONT_PTE_SIZE:
> +		return true;
> +	}
> +	pr_warn("%s: unrecognized huge page size 0x%lx\n",
> +			__func__, pagesize);
> +	return false;
> +}
> +#endif
> +
>  int pmd_huge(pmd_t pmd)
>  {
>  	return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
> -- 
> 2.7.4
>