[PATCH 14/27] mm: Do not flush TLB during protection change if !pte_present && !migration_entry

From: Mel Gorman
Date: Thu Aug 08 2013 - 10:05:29 EST

NUMA PTE scanning is expensive both in terms of the scanning itself and
the TLB flush if there are any updates. Currently non-present PTEs are
accounted for as an update and incurring a TLB flush where it is only
necessary for anonymous migration entries. This patch addresses the
problem and should reduce TLB flushes.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
mm/mprotect.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 1f4ab1c..8e7e9bd 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -101,8 +101,9 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
set_pte_at(mm, addr, pte,
+ pages++;
- pages++;
} while (pte++, addr += PAGE_SIZE, addr != end);

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/