break out numa_maps gather_pte_stats() checks

gather_pte_stats() does a number of checks on a target page
to see whether it should even be considered for statistics.
This breaks that code out in to a separate function so that
we can use it in the transparent hugepage case in the next
patch.

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Christoph Lameter <cl@gentwo.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 24 insertions, 15 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 61342a454bd9..9dca07e0758d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -904,6 +904,29 @@ static void gather_stats(struct page *page, struct numa_maps *md, int pte_dirty,
         md->node[page_to_nid(page)] += nr_pages;
 }
 
+static struct page *can_gather_numa_stats(pte_t pte, struct vm_area_struct *vma,
+                unsigned long addr)
+{
+        struct page *page;
+        int nid;
+
+        if (!pte_present(pte))
+                return NULL;
+
+        page = vm_normal_page(vma, addr, pte);
+        if (!page)
+                return NULL;
+
+        if (PageReserved(page))
+                return NULL;
+
+        nid = page_to_nid(page);
+        if (!node_isset(nid, node_states[N_HIGH_MEMORY]))
+                return NULL;
+
+        return page;
+}
+
 static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
                 unsigned long end, struct mm_walk *walk)
 {
@@ -915,23 +938,9 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
         md = walk->private;
         orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
         do {
-                struct page *page;
-                int nid;
-
-                if (!pte_present(*pte))
-                        continue;
-
-                page = vm_normal_page(md->vma, addr, *pte);
+                struct page *page = can_gather_numa_stats(*pte, md->vma, addr);
                 if (!page)
                         continue;
-
-                if (PageReserved(page))
-                        continue;
-
-                nid = page_to_nid(page);
-                if (!node_isset(nid, node_states[N_HIGH_MEMORY]))
-                        continue;
-
                 gather_stats(page, md, pte_dirty(*pte), 1);
 
         } while (pte++, addr += PAGE_SIZE, addr != end);