Messages in this thread | | | Date | Thu, 13 Nov 2008 00:27:06 +0100 | From | Nick Piggin <> | Subject | Re: [patch 3/8] x86 PAT: Add follow_pfnmp_pte routine to help tracking pfnmap pages |
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On Wed, Nov 12, 2008 at 01:26:50PM -0800, Venkatesh Pallipadi wrote: > > Add a generic interface to follow pfn in a pfnmap vma range. This is used by > one of the subsequent x86 PAT related patch to keep track of memory types > for vma regions across vma copy and free. > > Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> > Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> > > --- > include/linux/mm.h | 3 +++ > mm/memory.c | 43 +++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 46 insertions(+) > > Index: tip/include/linux/mm.h > =================================================================== > --- tip.orig/include/linux/mm.h 2008-11-06 15:41:43.000000000 -0800 > +++ tip/include/linux/mm.h 2008-11-10 09:44:45.000000000 -0800 > @@ -1223,6 +1223,9 @@ struct page *follow_page(struct vm_area_ > #define FOLL_GET 0x04 /* do get_page on page */ > #define FOLL_ANON 0x08 /* give ZERO_PAGE if no pgtable */ > > +unsigned long follow_pfnmap_pte(struct vm_area_struct *vma, > + unsigned long address, pte_t *ret_ptep); > + > typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr, > void *data); > extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, > Index: tip/mm/memory.c > =================================================================== > --- tip.orig/mm/memory.c 2008-11-06 15:41:43.000000000 -0800 > +++ tip/mm/memory.c 2008-11-10 09:44:45.000000000 -0800 > @@ -1111,6 +1111,49 @@ no_page_table: > return page; > } > > +unsigned long follow_pfnmap_pte(struct vm_area_struct *vma, > + unsigned long address, pte_t *ret_ptep) > +{
I think we'd typically return an int for functions like this. It probably wouldn't hurt to return more descriptive errors either. -EINVAL, perhaps, seems to fit best with what existing code there is doing.
> + pgd_t *pgd; > + pud_t *pud; > + pmd_t *pmd; > + pte_t *ptep, pte; > + spinlock_t *ptl; > + struct page *page; > + struct mm_struct *mm = vma->vm_mm; > + > + if (!is_pfn_mapping(vma)) > + goto err; > + > + page = NULL; > + pgd = pgd_offset(mm, address); > + if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) > + goto err; > + > + pud = pud_offset(pgd, address); > + if (pud_none(*pud) || unlikely(pud_bad(*pud))) > + goto err; > + > + pmd = pmd_offset(pud, address); > + if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) > + goto err; > + > + ptep = pte_offset_map_lock(mm, pmd, address, &ptl); > + > + pte = *ptep; > + if (!pte_present(pte)) > + goto err_unlock; > + > + *ret_ptep = pte; > + pte_unmap_unlock(ptep, ptl); > + return 0; > + > +err_unlock: > + pte_unmap_unlock(ptep, ptl); > +err: > + return -1; > +} > + > /* Can we do the FOLL_ANON optimization? */ > static inline int use_zero_page(struct vm_area_struct *vma) > { > > --
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