/proc/pid/smaps: fix dirty pages accounting

Currently, /proc/<pid>/smaps has wrong dirty pages accounting.
Shared_Dirty and Private_Dirty output only pte dirty pages and ignore
PG_dirty page flag.  It is difference against documentation, but also
inconsistent against Referenced field.  (Referenced checks both pte and
page flags)

This patch fixes it.

Test program:

 large-array.c
 ---------------------------------------------------
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>

 char array[1*1024*1024*1024L];

 int main(void)
 {
         memset(array, 1, sizeof(array));
         pause();

         return 0;
 }
 ---------------------------------------------------

Test case:
 1. run ./large-array
 2. cat /proc/`pidof large-array`/smaps
 3. swapoff -a
 4. cat /proc/`pidof large-array`/smaps again

Test result:
 <before patch>

00601000-40601000 rw-p 00000000 00:00 0
Size:            1048576 kB
Rss:             1048576 kB
Pss:             1048576 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:    218992 kB   <-- showed pages as clean incorrectly
Private_Dirty:    829584 kB
Referenced:       388364 kB
Swap:                  0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB

 <after patch>

00601000-40601000 rw-p 00000000 00:00 0
Size:            1048576 kB
Rss:             1048576 kB
Pss:             1048576 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:   1048576 kB  <-- fixed
Referenced:       388480 kB
Swap:                  0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 271afc48b9a5d58dd2874d41f8a08dfcae644481..1dbca4e8cc164d08276d4a1f5a875e7726fc7020 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -363,13 +363,13 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
                        mss->referenced += PAGE_SIZE;
                mapcount = page_mapcount(page);
                if (mapcount >= 2) {
-                       if (pte_dirty(ptent))
+                       if (pte_dirty(ptent) || PageDirty(page))
                                mss->shared_dirty += PAGE_SIZE;
                        else
                                mss->shared_clean += PAGE_SIZE;
                        mss->pss += (PAGE_SIZE << PSS_SHIFT) / mapcount;
                } else {
-                       if (pte_dirty(ptent))
+                       if (pte_dirty(ptent) || PageDirty(page))
                                mss->private_dirty += PAGE_SIZE;
                        else
                                mss->private_clean += PAGE_SIZE;