thp: skip transhuge pages in ksm for now
Andrea Arcangeli [Thu, 13 Jan 2011 23:47:00 +0000 (15:47 -0800)]
Skip transhuge pages in ksm for now.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/ksm.c

index b5b907c..5e7d5d3 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -430,7 +430,7 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item)
        page = follow_page(vma, addr, FOLL_GET);
        if (IS_ERR_OR_NULL(page))
                goto out;
-       if (PageAnon(page)) {
+       if (PageAnon(page) && !PageTransCompound(page)) {
                flush_anon_page(vma, page, addr);
                flush_dcache_page(page);
        } else {
@@ -1279,7 +1279,19 @@ next_mm:
                        if (ksm_test_exit(mm))
                                break;
                        *page = follow_page(vma, ksm_scan.address, FOLL_GET);
-                       if (!IS_ERR_OR_NULL(*page) && PageAnon(*page)) {
+                       if (IS_ERR_OR_NULL(*page)) {
+                               ksm_scan.address += PAGE_SIZE;
+                               cond_resched();
+                               continue;
+                       }
+                       if (PageTransCompound(*page)) {
+                               put_page(*page);
+                               ksm_scan.address &= HPAGE_PMD_MASK;
+                               ksm_scan.address += HPAGE_PMD_SIZE;
+                               cond_resched();
+                               continue;
+                       }
+                       if (PageAnon(*page)) {
                                flush_anon_page(vma, *page, ksm_scan.address);
                                flush_dcache_page(*page);
                                rmap_item = get_next_rmap_item(slot,
@@ -1293,8 +1305,7 @@ next_mm:
                                up_read(&mm->mmap_sem);
                                return rmap_item;
                        }
-                       if (!IS_ERR_OR_NULL(*page))
-                               put_page(*page);
+                       put_page(*page);
                        ksm_scan.address += PAGE_SIZE;
                        cond_resched();
                }