linux-kernel - Re: [PATCH v2 09/26] userfaultfd: wp: userfaultfd_pte/huge_pmd

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Message-ID: <20190221172141.GI2813@redhat.com>
Date:   Thu, 21 Feb 2019 12:21:41 -0500
From:   Jerome Glisse <jglisse@...hat.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Maya Gokhale <gokhale2@...l.gov>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Martin Cracauer <cracauer@...s.org>, Shaohua Li <shli@...com>,
        Marty McFadden <mcfadden8@...l.gov>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Denis Plotnikov <dplotnikov@...tuozzo.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Mel Gorman <mgorman@...e.de>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>
Subject: Re: [PATCH v2 09/26] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp()
 helpers

On Tue, Feb 12, 2019 at 10:56:15AM +0800, Peter Xu wrote:
> From: Andrea Arcangeli <aarcange@...hat.com>
> 
> Implement helpers methods to invoke userfaultfd wp faults more
> selectively: not only when a wp fault triggers on a vma with
> vma->vm_flags VM_UFFD_WP set, but only if the _PAGE_UFFD_WP bit is set
> in the pagetable too.
> 
> Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
> Signed-off-by: Peter Xu <peterx@...hat.com>

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

> ---
>  include/linux/userfaultfd_k.h | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
> index 38f748e7186e..c6590c58ce28 100644
> --- a/include/linux/userfaultfd_k.h
> +++ b/include/linux/userfaultfd_k.h
> @@ -14,6 +14,8 @@
>  #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */
>  
>  #include <linux/fcntl.h>
> +#include <linux/mm.h>
> +#include <asm-generic/pgtable_uffd.h>
>  
>  /*
>   * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
> @@ -55,6 +57,18 @@ static inline bool userfaultfd_wp(struct vm_area_struct *vma)
>  	return vma->vm_flags & VM_UFFD_WP;
>  }
>  
> +static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
> +				      pte_t pte)
> +{
> +	return userfaultfd_wp(vma) && pte_uffd_wp(pte);
> +}
> +
> +static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
> +					   pmd_t pmd)
> +{
> +	return userfaultfd_wp(vma) && pmd_uffd_wp(pmd);
> +}
> +
>  static inline bool userfaultfd_armed(struct vm_area_struct *vma)
>  {
>  	return vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP);
> @@ -104,6 +118,19 @@ static inline bool userfaultfd_wp(struct vm_area_struct *vma)
>  	return false;
>  }
>  
> +static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
> +				      pte_t pte)
> +{
> +	return false;
> +}
> +
> +static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
> +					   pmd_t pmd)
> +{
> +	return false;
> +}
> +
> +
>  static inline bool userfaultfd_armed(struct vm_area_struct *vma)
>  {
>  	return false;
> -- 
> 2.17.1
>