[PATCH 3.8 79/91] mm: Account for a THP NUMA hinting update as one PTE update

Kamal Mostafa kamal at canonical.com
Fri Nov 8 02:15:34 UTC 2013 -stable review patch.  If anyone has any objections, please let me know.


From: Mel Gorman <mgorman at suse.de>

commit 0255d491848032f6c601b6410c3b8ebded3a37b1 upstream.

A THP PMD update is accounted for as 512 pages updated in vmstat.  This is
large difference when estimating the cost of automatic NUMA balancing and
can be misleading when comparing results that had collapsed versus split
THP. This patch addresses the accounting issue.

Signed-off-by: Mel Gorman <mgorman at suse.de>
Reviewed-by: Rik van Riel <riel at redhat.com>
Cc: Andrea Arcangeli <aarcange at redhat.com>
Cc: Johannes Weiner <hannes at cmpxchg.org>
Cc: Srikar Dronamraju <srikar at linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz at infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-10-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 mm/mprotect.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 94722a4..2bbb648 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -145,7 +145,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
 				split_huge_page_pmd(vma, addr, pmd);
 			else if (change_huge_pmd(vma, pmd, addr, newprot,
 						 prot_numa)) {
-				pages += HPAGE_PMD_NR;
+				pages++;
 			/* fall through */

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