linux-kernel - Re: [PATCHv3 08/11] sparc64: update pmdp

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Date:   Wed, 13 Sep 2017 10:36:13 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vineet Gupta <vgupta@...opsys.com>,
        Russell King <linux@...linux.org.uk>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        "David S. Miller" <davem@...emloft.net>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Andrea Arcangeli <aarcange@...hat.com>
Cc:     linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Nitin Gupta <nitin.m.gupta@...cle.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCHv3 08/11] sparc64: update pmdp_invalidate to return old pmd value

"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> writes:

> From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>


You got the author wrong there.

>
> It's required to avoid loosing dirty and accessed bits.
>
> Signed-off-by: Nitin Gupta <nitin.m.gupta@...cle.com>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
>  arch/sparc/include/asm/pgtable_64.h |  2 +-
>  arch/sparc/mm/tlb.c                 | 23 ++++++++++++++++++-----
>  2 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> index 4fefe3762083..83b06c98bb94 100644
> --- a/arch/sparc/include/asm/pgtable_64.h
> +++ b/arch/sparc/include/asm/pgtable_64.h
> @@ -979,7 +979,7 @@ void update_mmu_cache_pmd(struct vm_area_struct *vma, unsigned long addr,
>  			  pmd_t *pmd);
>
>  #define __HAVE_ARCH_PMDP_INVALIDATE
> -extern void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
> +extern pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
>  			    pmd_t *pmdp);
>
>  #define __HAVE_ARCH_PGTABLE_DEPOSIT
> diff --git a/arch/sparc/mm/tlb.c b/arch/sparc/mm/tlb.c
> index ee8066c3d96c..d36c65fc55cf 100644
> --- a/arch/sparc/mm/tlb.c
> +++ b/arch/sparc/mm/tlb.c
> @@ -218,17 +218,28 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
>  	}
>  }
>
> +static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
> +		unsigned long address, pmd_t *pmdp, pmd_t pmd)
> +{
> +	pmd_t old;
> +
> +	{
> +		old = *pmdp;
> +	} while (cmpxchg64(&pmdp->pmd, old.pmd, pmd.pmd) != old.pmd);
> +
> +	return old;
> +}
> +
>  /*
>   * This routine is only called when splitting a THP
>   */
> -void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
> +pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
>  		     pmd_t *pmdp)
>  {
> -	pmd_t entry = *pmdp;
> -
> -	pmd_val(entry) &= ~_PAGE_VALID;
> +	pmd_t old, entry;
>
> -	set_pmd_at(vma->vm_mm, address, pmdp, entry);
> +	entry = __pmd(pmd_val(*pmdp) & ~_PAGE_VALID);
> +	old = pmdp_establish(vma, address, pmdp, entry);
>  	flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
>
>  	/*
> @@ -239,6 +250,8 @@ void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
>  	if ((pmd_val(entry) & _PAGE_PMD_HUGE) &&
>  	    !is_huge_zero_page(pmd_page(entry)))
>  		(vma->vm_mm)->context.thp_pte_count--;
> +
> +	return old;
>  }
>
>  void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
> -- 
> 2.14.1