thp: skip transhuge pages in ksm for now

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>

1 files changed, 15 insertions, 4 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index b5b907cb0f90..5e7d5d35ea82 100644
--- 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();
                 }