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SubjectRe: [x86 PAT PATCH 1/2] x86, pat: remove the dependency on 'vm_pgoff' in track/untrack pfn vma routines
Suresh Siddha wrote:
> 'pfn' argument for track_pfn_vma_new() can be used for reserving the attribute
> for the pfn range. No need to depend on 'vm_pgoff'
>
> Similarly, untrack_pfn_vma() can depend on the 'pfn' argument if it
> is non-zero or can use follow_phys() to get the starting value of the pfn
> range.
>
> Also the non zero 'size' argument can be used instead of recomputing
> it from vma.
>
> This cleanup also prepares the ground for the track/untrack pfn vma routines
> to take over the ownership of setting PAT specific vm_flag in the 'vma'.
>
> Signed-off-by: Suresh Siddha<suresh.b.siddha@intel.com>
> Cc: Venkatesh Pallipadi<venki@google.com>
> Cc: Konstantin Khlebnikov<khlebnikov@openvz.org>
> ---
> arch/x86/mm/pat.c | 30 +++++++++++++++++-------------
> 1 files changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
> index f6ff57b..617f42b 100644
> --- a/arch/x86/mm/pat.c
> +++ b/arch/x86/mm/pat.c
> @@ -693,14 +693,10 @@ int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
> unsigned long pfn, unsigned long size)
> {
> unsigned long flags;
> - resource_size_t paddr;
> - unsigned long vma_size = vma->vm_end - vma->vm_start;
>
> - if (is_linear_pfn_mapping(vma)) {
> - /* reserve the whole chunk starting from vm_pgoff */
> - paddr = (resource_size_t)vma->vm_pgoff<< PAGE_SHIFT;
> - return reserve_pfn_range(paddr, vma_size, prot, 0);
> - }
> + /* reserve the whole chunk starting from pfn */
> + if (is_linear_pfn_mapping(vma))
> + return reserve_pfn_range(pfn, size, prot, 0);

you mix here pfn and paddr: old code passes paddr as first argument of reserve_pfn_range().

>
> if (!pat_enabled)
> return 0;
> @@ -716,20 +712,28 @@ int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
> /*
> * untrack_pfn_vma is called while unmapping a pfnmap for a region.
> * untrack can be called for a specific region indicated by pfn and size or
> - * can be for the entire vma (in which case size can be zero).
> + * can be for the entire vma (in which case pfn, size are zero).
> */
> void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
> unsigned long size)
> {
> resource_size_t paddr;
> - unsigned long vma_size = vma->vm_end - vma->vm_start;
> + unsigned long prot;
>
> - if (is_linear_pfn_mapping(vma)) {
> - /* free the whole chunk starting from vm_pgoff */
> - paddr = (resource_size_t)vma->vm_pgoff<< PAGE_SHIFT;
> - free_pfn_range(paddr, vma_size);
> + if (!is_linear_pfn_mapping(vma))
> return;
> +
> + /* free the chunk starting from pfn or the whole chunk */
> + paddr = (resource_size_t)pfn;
> + if (!paddr&& !size) {
> + if (follow_phys(vma, vma->vm_start, 0,&prot,&paddr)) {
> + WARN_ON_ONCE(1);
> + return;
> + }
> +
> + size = vma->vm_end - vma->vm_start;
> }
> + free_pfn_range(paddr, size);
> }
>
> pgprot_t pgprot_writecombine(pgprot_t prot)



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