smaps: fix wrong rss count

A long time ago we regarded zero page as file_rss and vm_normal_page
doesn't return NULL.

But now, we reinstated ZERO_PAGE and vm_normal_page's implementation can
return NULL in case of zero page.  Also we don't count it with file_rss
any more.

Then, RSS and PSS can't be matched.  For consistency, Let's ignore zero
page in smaps_pte_range.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Acked-by: Matt Mackall <mpm@selenic.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 47c03f4336b8..f277c4a111cb 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -361,12 +361,11 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
                 if (!pte_present(ptent))
                         continue;
 
-                mss->resident += PAGE_SIZE;
-
                 page = vm_normal_page(vma, addr, ptent);
                 if (!page)
                         continue;
 
+                mss->resident += PAGE_SIZE;
                 /* Accumulate the size in pages that have been accessed. */
                 if (pte_young(ptent) || PageReferenced(page))
                         mss->referenced += PAGE_SIZE;