mm: don't assume anonymous pages have SwapBacked flag

There are a few places the code assumes anonymous pages should have
SwapBacked flag set.  MADV_FREE pages are anonymous pages but we are
going to add them to LRU_INACTIVE_FILE list and clear SwapBacked flag
for them.  The assumption doesn't hold any more, so fix them.

Link: http://lkml.kernel.org/r/3945232c0df3dd6c4ef001976f35a95f18dcb407.1487965799.git.shli@fb.com
Signed-off-by: Shaohua Li <shli@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 5 deletions

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index ba40b7f673f4..88e4b1737c90 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -483,8 +483,7 @@ void __khugepaged_exit(struct mm_struct *mm)
 
 static void release_pte_page(struct page *page)
 {
-        /* 0 stands for page_is_file_cache(page) == false */
-        dec_node_page_state(page, NR_ISOLATED_ANON + 0);
+        dec_node_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page));
         unlock_page(page);
         putback_lru_page(page);
 }
@@ -532,7 +531,6 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
 
                 VM_BUG_ON_PAGE(PageCompound(page), page);
                 VM_BUG_ON_PAGE(!PageAnon(page), page);
-                VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
 
                 /*
                  * We can do it before isolate_lru_page because the
@@ -579,8 +577,8 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
                         result = SCAN_DEL_PAGE_LRU;
                         goto out;
                 }
-                /* 0 stands for page_is_file_cache(page) == false */
-                inc_node_page_state(page, NR_ISOLATED_ANON + 0);
+                inc_node_page_state(page,
+                                NR_ISOLATED_ANON + page_is_file_cache(page));
                 VM_BUG_ON_PAGE(!PageLocked(page), page);
                 VM_BUG_ON_PAGE(PageLRU(page), page);