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Date:   Mon, 22 Apr 2019 16:15:05 -0400
From:   Jerome Glisse <jglisse@...hat.com>
To:     Laurent Dufour <ldufour@...ux.ibm.com>
Cc:     akpm@...ux-foundation.org, mhocko@...nel.org, peterz@...radead.org,
        kirill@...temov.name, ak@...ux.intel.com, dave@...olabs.net,
        jack@...e.cz, Matthew Wilcox <willy@...radead.org>,
        aneesh.kumar@...ux.ibm.com, benh@...nel.crashing.org,
        mpe@...erman.id.au, paulus@...ba.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
        Will Deacon <will.deacon@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        sergey.senozhatsky.work@...il.com,
        Andrea Arcangeli <aarcange@...hat.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        kemi.wang@...el.com, Daniel Jordan <daniel.m.jordan@...cle.com>,
        David Rientjes <rientjes@...gle.com>,
        Ganesh Mahendran <opensource.ganesh@...il.com>,
        Minchan Kim <minchan@...nel.org>,
        Punit Agrawal <punitagrawal@...il.com>,
        vinayak menon <vinayakm.list@...il.com>,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        zhong jiang <zhongjiang@...wei.com>,
        Haiyan Song <haiyanx.song@...el.com>,
        Balbir Singh <bsingharora@...il.com>, sj38.park@...il.com,
        Michel Lespinasse <walken@...gle.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        haren@...ux.vnet.ibm.com, npiggin@...il.com,
        paulmck@...ux.vnet.ibm.com, Tim Chen <tim.c.chen@...ux.intel.com>,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: Re: [PATCH v12 16/31] mm: introduce __vm_normal_page()

On Tue, Apr 16, 2019 at 03:45:07PM +0200, Laurent Dufour wrote:
> When dealing with the speculative fault path we should use the VMA's field
> cached value stored in the vm_fault structure.
> 
> Currently vm_normal_page() is using the pointer to the VMA to fetch the
> vm_flags value. This patch provides a new __vm_normal_page() which is
> receiving the vm_flags flags value as parameter.
> 
> Note: The speculative path is turned on for architecture providing support
> for special PTE flag. So only the first block of vm_normal_page is used
> during the speculative path.
> 
> Signed-off-by: Laurent Dufour <ldufour@...ux.ibm.com>

Reviewed-by: Jérôme Glisse <jglisse@...hat.com>

> ---
>  include/linux/mm.h | 18 +++++++++++++++---
>  mm/memory.c        | 21 ++++++++++++---------
>  2 files changed, 27 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index f465bb2b049e..f14b2c9ddfd4 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1421,9 +1421,21 @@ static inline void INIT_VMA(struct vm_area_struct *vma)
>  #endif
>  }
>  
> -struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
> -			     pte_t pte, bool with_public_device);
> -#define vm_normal_page(vma, addr, pte) _vm_normal_page(vma, addr, pte, false)
> +struct page *__vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
> +			      pte_t pte, bool with_public_device,
> +			      unsigned long vma_flags);
> +static inline struct page *_vm_normal_page(struct vm_area_struct *vma,
> +					    unsigned long addr, pte_t pte,
> +					    bool with_public_device)
> +{
> +	return __vm_normal_page(vma, addr, pte, with_public_device,
> +				vma->vm_flags);
> +}
> +static inline struct page *vm_normal_page(struct vm_area_struct *vma,
> +					  unsigned long addr, pte_t pte)
> +{
> +	return _vm_normal_page(vma, addr, pte, false);
> +}
>  
>  struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
>  				pmd_t pmd);
> diff --git a/mm/memory.c b/mm/memory.c
> index 85ec5ce5c0a8..be93f2c8ebe0 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -533,7 +533,8 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
>  }
>  
>  /*
> - * vm_normal_page -- This function gets the "struct page" associated with a pte.
> + * __vm_normal_page -- This function gets the "struct page" associated with
> + * a pte.
>   *
>   * "Special" mappings do not wish to be associated with a "struct page" (either
>   * it doesn't exist, or it exists but they don't want to touch it). In this
> @@ -574,8 +575,9 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
>   * PFNMAP mappings in order to support COWable mappings.
>   *
>   */
> -struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
> -			     pte_t pte, bool with_public_device)
> +struct page *__vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
> +			      pte_t pte, bool with_public_device,
> +			      unsigned long vma_flags)
>  {
>  	unsigned long pfn = pte_pfn(pte);
>  
> @@ -584,7 +586,7 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
>  			goto check_pfn;
>  		if (vma->vm_ops && vma->vm_ops->find_special_page)
>  			return vma->vm_ops->find_special_page(vma, addr);
> -		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
> +		if (vma_flags & (VM_PFNMAP | VM_MIXEDMAP))
>  			return NULL;
>  		if (is_zero_pfn(pfn))
>  			return NULL;
> @@ -620,8 +622,8 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
>  
>  	/* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
>  
> -	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
> -		if (vma->vm_flags & VM_MIXEDMAP) {
> +	if (unlikely(vma_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
> +		if (vma_flags & VM_MIXEDMAP) {
>  			if (!pfn_valid(pfn))
>  				return NULL;
>  			goto out;
> @@ -630,7 +632,7 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
>  			off = (addr - vma->vm_start) >> PAGE_SHIFT;
>  			if (pfn == vma->vm_pgoff + off)
>  				return NULL;
> -			if (!is_cow_mapping(vma->vm_flags))
> +			if (!is_cow_mapping(vma_flags))
>  				return NULL;
>  		}
>  	}
> @@ -2532,7 +2534,8 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf)
>  {
>  	struct vm_area_struct *vma = vmf->vma;
>  
> -	vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
> +	vmf->page = __vm_normal_page(vma, vmf->address, vmf->orig_pte, false,
> +				     vmf->vma_flags);
>  	if (!vmf->page) {
>  		/*
>  		 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
> @@ -3706,7 +3709,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
>  	ptep_modify_prot_commit(vma, vmf->address, vmf->pte, old_pte, pte);
>  	update_mmu_cache(vma, vmf->address, vmf->pte);
>  
> -	page = vm_normal_page(vma, vmf->address, pte);
> +	page = __vm_normal_page(vma, vmf->address, pte, false, vmf->vma_flags);
>  	if (!page) {
>  		pte_unmap_unlock(vmf->pte, vmf->ptl);
>  		return 0;
> -- 
> 2.21.0
> 

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