Re: [PATCH] calculation of pgoff in do_linear_fault() uses mixed units

From: Nick Piggin
Date: Wed Aug 15 2007 - 22:52:34 EST


On Wed, Aug 15, 2007 at 12:43:26PM -0500, Dean Nelson wrote:
> The calculation of pgoff in do_linear_fault() should use PAGE_SHIFT and not
> PAGE_CACHE_SHIFT since vma->vm_pgoff is in units of PAGE_SIZE and not
> PAGE_CACHE_SIZE. At the moment linux/pagemap.h has PAGE_CACHE_SHIFT defined
> as PAGE_SHIFT, but should that ever change this calculation would break.
>
> Signed-off-by: Dean Nelson <dcn@xxxxxxx>
>

Acked-by: Nick Piggin <npiggin@xxxxxxx>

>
> Index: linux-2.6/mm/memory.c
> ===================================================================
> --- linux-2.6.orig/mm/memory.c 2007-08-14 06:42:18.322378070 -0500
> +++ linux-2.6/mm/memory.c 2007-08-15 12:30:51.621604739 -0500
> @@ -2465,7 +2465,7 @@
> int write_access, pte_t orig_pte)
> {
> pgoff_t pgoff = (((address & PAGE_MASK)
> - - vma->vm_start) >> PAGE_CACHE_SHIFT) + vma->vm_pgoff;
> + - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
> unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);
>
> return __do_fault(mm, vma, address, page_table, pmd, pgoff,
-
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