linux-kernel - Re: [PATCH 1/2] mm: Add and export vmf_insert_mixed

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Date:   Wed, 27 Nov 2019 09:42:45 +0100
From:   Christian König <christian.koenig@....com>
To:     Thomas Hellström (VMware) 
        <thomas_os@...pmail.org>, dri-devel@...ts.freedesktop.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-graphics-maintainer@...are.com
Cc:     Thomas Hellstrom <thellstrom@...are.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Jérôme Glisse <jglisse@...hat.com>
Subject: Re: [PATCH 1/2] mm: Add and export vmf_insert_mixed_prot()

Am 26.11.19 um 21:27 schrieb Thomas Hellström (VMware):
> From: Thomas Hellstrom <thellstrom@...are.com>
>
> The TTM module today uses a hack to be able to set a different page
> protection than struct vm_area_struct::vm_page_prot. To be able to do
> this properly, add and export vmf_insert_mixed_prot().
>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
> Cc: Ralph Campbell <rcampbell@...dia.com>
> Cc: "Jérôme Glisse" <jglisse@...hat.com>
> Cc: "Christian König" <christian.koenig@....com>
> Signed-off-by: Thomas Hellstrom <thellstrom@...are.com>

Acked-by: Christian König <christian.koenig@....com>

> ---
>   include/linux/mm.h |  2 ++
>   mm/memory.c        | 15 +++++++++++----
>   2 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index cc292273e6ba..29575d3c1e47 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2548,6 +2548,8 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
>   			unsigned long pfn, pgprot_t pgprot);
>   vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
>   			pfn_t pfn);
> +vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
> +			pfn_t pfn, pgprot_t pgprot);
>   vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
>   		unsigned long addr, pfn_t pfn);
>   int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
> diff --git a/mm/memory.c b/mm/memory.c
> index b1ca51a079f2..28f162e28144 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1719,9 +1719,9 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
>   }
>   
>   static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
> -		unsigned long addr, pfn_t pfn, bool mkwrite)
> +		unsigned long addr, pfn_t pfn, pgprot_t pgprot,
> +		bool mkwrite)
>   {
> -	pgprot_t pgprot = vma->vm_page_prot;
>   	int err;
>   
>   	BUG_ON(!vm_mixed_ok(vma, pfn));
> @@ -1764,10 +1764,17 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
>   	return VM_FAULT_NOPAGE;
>   }
>   
> +vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
> +				 pfn_t pfn, pgprot_t pgprot)
> +{
> +	return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
> +}
> +EXPORT_SYMBOL(vmf_insert_mixed_prot);
> +
>   vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
>   		pfn_t pfn)
>   {
> -	return __vm_insert_mixed(vma, addr, pfn, false);
> +	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
>   }
>   EXPORT_SYMBOL(vmf_insert_mixed);
>   
> @@ -1779,7 +1786,7 @@ EXPORT_SYMBOL(vmf_insert_mixed);
>   vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
>   		unsigned long addr, pfn_t pfn)
>   {
> -	return __vm_insert_mixed(vma, addr, pfn, true);
> +	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
>   }
>   EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
>