mm: report the MMU pagesize in /proc/pid/smaps

The KernelPageSize entry in /proc/pid/smaps is the pagesize used by the
kernel to back a VMA.  This matches the size used by the MMU in the
majority of cases.  However, one counter-example occurs on PPC64 kernels
whereby a kernel using 64K as a base pagesize may still use 4K pages for
the MMU on older processor.  To distinguish, this patch reports
MMUPageSize as the pagesize used by the MMU in /proc/pid/smaps.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: "KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 13 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index 26f0d0ab27a5..b1dafb6a9743 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -18,6 +18,12 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
                               pte_t *ptep);
 
 /*
+ * The version of vma_mmu_pagesize() in arch/powerpc/mm/hugetlbpage.c needs
+ * to override the version in mm/hugetlb.c
+ */
+#define vma_mmu_pagesize vma_mmu_pagesize
+
+/*
  * If the arch doesn't supply something else, assume that hugepage
  * size aligned regions are ok without further preparation.
  */
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 201c7a5486cb..9920d6a7cf29 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -512,6 +512,13 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
         return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1, 0);
 }
 
+unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
+{
+        unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
+
+        return 1UL << mmu_psize_to_shift(psize);
+}
+
 /*
  * Called by asm hashtable.S for doing lazy icache flush
  */