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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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