[PATCH v16 14/22] mm/thp: add tail pages into lru anyway in split_huge_page()

[Alex Shi]

split_huge_page() must start with PageLRU(head), but lru bit *maybe*
cleared by isolate_lru_page, anyway the head still in lru list, since we
still held the lru_lock.

Signed-off-by: Alex Shi <alex....@linux.alibaba.com>
Cc: Kirill A. Shutemov <kir...@shutemov.name>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: Matthew Wilcox <wi...@infradead.org>
Cc: Hugh Dickins <hu...@google.com>
Cc: Mika Penttilä <mika.pentt...@nextfour.com>
Cc: linux...@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 mm/huge_memory.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d866b6e43434..4fe7b92c9330 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2348,15 +2348,18 @@ static void lru_add_page_tail(struct page *head, struct 
page *page_tail,
        VM_BUG_ON_PAGE(PageLRU(page_tail), head);
        lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
 
-       if (!list)
-               SetPageLRU(page_tail);
-
-       if (likely(PageLRU(head)))
-               list_add_tail(&page_tail->lru, &head->lru);
-       else if (list) {
+       if (list) {
                /* page reclaim is reclaiming a huge page */
                get_page(page_tail);
                list_add_tail(&page_tail->lru, list);
+       } else {
+               /*
+                * Split start from PageLRU(head), but lru bit maybe cleared
+                * by isolate_lru_page, but head still in lru list, since we
+                * held the lru_lock.
+                */
+               SetPageLRU(page_tail);
+               list_add_tail(&page_tail->lru, &head->lru);
        }
 }
 
-- 
1.8.3.1