linux-kernel - Re: [PATCH v4 1/2] mm: Add a vmf_insert_mixed

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Date:   Thu, 12 Dec 2019 08:51:29 +0000
From:   Thomas Hellstrom <thellstrom@...are.com>
To:     Thomas Hellström (VMware) 
        <thomas_os@...pmail.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
CC:     Pv-drivers <Pv-drivers@...are.com>,
        Linux-graphics-maintainer <Linux-graphics-maintainer@...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>,
        Christian König <christian.koenig@....com>
Subject: Re: [PATCH v4 1/2] mm: Add a vmf_insert_mixed_prot() function

On 12/12/19 9:48 AM, Thomas Hellström (VMware) wrote:
> 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 the needed vm functionality as 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 ++
>  include/linux/mm_types.h |  7 ++++++-
>  mm/memory.c              | 43 ++++++++++++++++++++++++++++++++++++----
>  3 files changed, 47 insertions(+), 5 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/include/linux/mm_types.h b/include/linux/mm_types.h
> index 2222fa795284..ac96afdbb4bc 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -307,7 +307,12 @@ struct vm_area_struct {
>  	/* Second cache line starts here. */
>  
>  	struct mm_struct *vm_mm;	/* The address space we belong to. */
> -	pgprot_t vm_page_prot;		/* Access permissions of this VMA. */
> +
> +	/*
> +	 * Access permissions of this VMA.
> +	 * See vmf_insert_mixed() for discussion.

Typo. will of course be vmf_insert_mixed_prot() in the final version.