[PATCH] mm: Use linear_page_index() in do_fault()

[PATCH] mm: Use linear_page_index() in do_fault()

[Matthew Wilcox]

do_fault assumes that PAGE_SIZE is the same as PAGE_CACHE_SIZE.
Use linear_page_index() to calculate pgoff in the correct units.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
---
 mm/memory.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 554816b..5224c06 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3161,8 +3161,7 @@ static int do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 		unsigned long address, pte_t *page_table, pmd_t *pmd,
 		unsigned int flags, pte_t orig_pte)
 {
-	pgoff_t pgoff = (((address & PAGE_MASK)
-			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+	pgoff_t pgoff = linear_page_index(vma, address);
 
 	pte_unmap(page_table);
 	/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
-- 
2.7.0.rc3

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Re: [PATCH] mm: Use linear_page_index() in do_fault()

[Kirill A. Shutemov]

On Sun, Jan 31, 2016 at 11:13:21PM +1100, Matthew Wilcox wrote:
> do_fault assumes that PAGE_SIZE is the same as PAGE_CACHE_SIZE.
> Use linear_page_index() to calculate pgoff in the correct units.
> 
> Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

'linear' part of helper name is not relevant any more since we've dropped
non-linear mappings. Probably, we should rename helpers.

> ---
>  mm/memory.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index 554816b..5224c06 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3161,8 +3161,7 @@ static int do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
>  		unsigned long address, pte_t *page_table, pmd_t *pmd,
>  		unsigned int flags, pte_t orig_pte)
>  {
> -	pgoff_t pgoff = (((address & PAGE_MASK)
> -			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
> +	pgoff_t pgoff = linear_page_index(vma, address);
>  
>  	pte_unmap(page_table);
>  	/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
> -- 
> 2.7.0.rc3
> 
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-- 
 Kirill A. Shutemov

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Re: [PATCH] mm: Use linear_page_index() in do_fault()

[Matthew Wilcox]

On Mon, Feb 01, 2016 at 03:06:38PM +0200, Kirill A. Shutemov wrote:
> On Sun, Jan 31, 2016 at 11:13:21PM +1100, Matthew Wilcox wrote:
> > do_fault assumes that PAGE_SIZE is the same as PAGE_CACHE_SIZE.
> > Use linear_page_index() to calculate pgoff in the correct units.
> > 
> > Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
> 
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> 
> 'linear' part of helper name is not relevant any more since we've dropped
> non-linear mappings. Probably, we should rename helpers.

Ah, that's what it was named for.  Yes, probably.

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