mm: Account for a THP NUMA hinting update as one PTE update

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@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-10-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 94722a4d6b438311de1d1690d81a0d598a907339..2bbb648ea73f278478979573493e6cebb4044de4 100644 (file)
--- 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++;
                                continue;
                        }
                        /* fall through */