mm/balloon_compaction: fix deflation when compaction is disabled

If CONFIG_BALLOON_COMPACTION=n balloon_page_insert() does not link pages
with balloon and doesn't set PagePrivate flag, as a result
balloon_page_dequeue() cannot get any pages because it thinks that all
of them are isolated.  Without balloon compaction nobody can isolate
ballooned pages.  It's safe to remove this check.

Fixes: d6d86c0a7f8d ("mm/balloon_compaction: redesign ballooned pages management").
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Reported-by: Matt Mullins <mmullins@mmlx.us>
Cc: <stable@vger.kernel.org>	[3.17]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index b3cbe19..fcad832 100644 (file)
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -68,11 +68,13 @@ struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
                 * to be released by the balloon driver.
                 */
                if (trylock_page(page)) {
+#ifdef CONFIG_BALLOON_COMPACTION
                        if (!PagePrivate(page)) {
                                /* raced with isolation */
                                unlock_page(page);
                                continue;
                        }
+#endif
                        spin_lock_irqsave(&b_dev_info->pages_lock, flags);
                        balloon_page_delete(page);
                        __count_vm_event(BALLOON_DEFLATE);