linux-kernel - Re: [PATCH 1/2] mm: move vma_is_anonymous check within pmd_move_must

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Message-ID: <008301d238d4$fabdf160$f039d420$@alibaba-inc.com>
Date:   Mon, 07 Nov 2016 16:57:33 +0800
From:   "Hillf Danton" <hillf.zj@...baba-inc.com>
To:     "'Aneesh Kumar K.V'" <aneesh.kumar@...ux.vnet.ibm.com>,
        <akpm@...ux-foundation.org>, <benh@...nel.crashing.org>,
        <paulus@...ba.org>, <mpe@...erman.id.au>,
        "'Kirill A . Shutemov'" <kirill@...temov.name>
Cc:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 1/2] mm: move vma_is_anonymous check within pmd_move_must_withdraw

On Monday, November 07, 2016 4:35 PM Aneesh Kumar K.V
> 
> Architectures like ppc64 want to use page table deposit/withraw
> even with huge pmd dax entries. Allow arch to override the
> vma_is_anonymous check by moving that to pmd_move_must_withdraw
> function
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
> ---
>  include/asm-generic/pgtable.h | 12 ------------
>  mm/huge_memory.c              | 17 +++++++++++++++--
>  2 files changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index c4f8fd2fd384..324990273ad2 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -653,18 +653,6 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
>  }
>  #endif
> 
> -#ifndef pmd_move_must_withdraw
> -static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
> -					 spinlock_t *old_pmd_ptl)
> -{
> -	/*
> -	 * With split pmd lock we also need to move preallocated
> -	 * PTE page table if new_pmd is on different PMD page table.
> -	 */
> -	return new_pmd_ptl != old_pmd_ptl;
> -}
> -#endif
> -
>  /*
>   * This function is meant to be used by sites walking pagetables with
>   * the mmap_sem hold in read mode to protect against MADV_DONTNEED and
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index cdcd25cb30fe..1ac1b0ca63c4 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1424,6 +1424,20 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>  	return 1;
>  }
> 
> +#ifndef pmd_move_must_withdraw
> +static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
> +					 spinlock_t *old_pmd_ptl)
> +{
> +	/*
> +	 * With split pmd lock we also need to move preallocated
> +	 * PTE page table if new_pmd is on different PMD page table.
> +	 *
> +	 * We also don't deposit and withdraw tables for file pages.
> +	 */
> +	return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);

Stray git merge?

> +}
> +#endif
> +
>  bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
>  		  unsigned long new_addr, unsigned long old_end,
>  		  pmd_t *old_pmd, pmd_t *new_pmd)
> @@ -1458,8 +1472,7 @@ bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
>  		pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
>  		VM_BUG_ON(!pmd_none(*new_pmd));
> 
> -		if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
> -				vma_is_anonymous(vma)) {
> +		if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
>  			pgtable_t pgtable;
>  			pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
>  			pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
> --
> 2.10.2
>