Re: [PATCH] Add a new vm flag to track full pfnmap at mmap

[Nick Piggin <npiggin@suse.de>]

On Fri, Mar 13, 2009 at 04:35:44PM -0700, Pallipadi, Venkatesh wrote:
> 
> Add a new vm flag VM_PFN_AT_MMAP to identify a PFNMAP that is
> fully mapped with remap_pfn_range. Patch removes the overloading
> of VM_INSERTPAGE from the earlier patch.
> 

Acked-by: Nick Piggin <npiggin@suse.de>

> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
> ---
>  include/linux/mm.h |   16 +++-------------
>  mm/memory.c        |    4 ++--
>  2 files changed, 5 insertions(+), 15 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 3daa05f..b1ea37f 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -98,12 +98,13 @@ extern unsigned int kobjsize(const void *objp);
>  #define VM_HUGETLB	0x00400000	/* Huge TLB Page VM */
>  #define VM_NONLINEAR	0x00800000	/* Is non-linear (remap_file_pages) */
>  #define VM_MAPPED_COPY	0x01000000	/* T if mapped copy of data (nommu mmap) */
> -#define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it. Refer note in VM_PFNMAP_AT_MMAP below */
> +#define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it */
>  #define VM_ALWAYSDUMP	0x04000000	/* Always include in core dumps */
>  
>  #define VM_CAN_NONLINEAR 0x08000000	/* Has ->fault & does nonlinear pages */
>  #define VM_MIXEDMAP	0x10000000	/* Can contain "struct page" and pure PFN pages */
>  #define VM_SAO		0x20000000	/* Strong Access Ordering (powerpc) */
> +#define VM_PFN_AT_MMAP	0x40000000	/* PFNMAP vma that is fully mapped at mmap time */
>  
>  #ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */
>  #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
> @@ -127,17 +128,6 @@ extern unsigned int kobjsize(const void *objp);
>  #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
>  
>  /*
> - * pfnmap vmas that are fully mapped at mmap time (not mapped on fault).
> - * Used by x86 PAT to identify such PFNMAP mappings and optimize their handling.
> - * Note VM_INSERTPAGE flag is overloaded here. i.e,
> - * VM_INSERTPAGE && !VM_PFNMAP implies
> - *     The vma has had "vm_insert_page()" done on it
> - * VM_INSERTPAGE && VM_PFNMAP implies
> - *     The vma is PFNMAP with full mapping at mmap time
> - */
> -#define VM_PFNMAP_AT_MMAP (VM_INSERTPAGE | VM_PFNMAP)
> -
> -/*
>   * mapping from the currently active vm_flags protection bits (the
>   * low four bits) to a page protection mask..
>   */
> @@ -156,7 +146,7 @@ extern pgprot_t protection_map[16];
>   */
>  static inline int is_linear_pfn_mapping(struct vm_area_struct *vma)
>  {
> -	return ((vma->vm_flags & VM_PFNMAP_AT_MMAP) == VM_PFNMAP_AT_MMAP);
> +	return (vma->vm_flags & VM_PFN_AT_MMAP);
>  }
>  
>  static inline int is_pfn_mapping(struct vm_area_struct *vma)
> diff --git a/mm/memory.c b/mm/memory.c
> index e6aced9..302591f 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1677,7 +1677,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
>  	 */
>  	if (addr == vma->vm_start && end == vma->vm_end) {
>  		vma->vm_pgoff = pfn;
> -		vma->vm_flags |= VM_PFNMAP_AT_MMAP;
> +		vma->vm_flags |= VM_PFN_AT_MMAP;
>  	} else if (is_cow_mapping(vma->vm_flags))
>  		return -EINVAL;
>  
> @@ -1690,7 +1690,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
>  		 * needed from higher level routine calling unmap_vmas
>  		 */
>  		vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
> -		vma->vm_flags &= ~VM_PFNMAP_AT_MMAP;
> +		vma->vm_flags &= ~VM_PFN_AT_MMAP;
>  		return -EINVAL;
>  	}
>  
> -- 
> 1.6.0.6