From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752009AbaH3Qli (ORCPT ); Sat, 30 Aug 2014 12:41:38 -0400 Received: from mail-la0-f51.google.com ([209.85.215.51]:56164 "EHLO mail-la0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751932AbaH3QlZ (ORCPT ); Sat, 30 Aug 2014 12:41:25 -0400 Subject: [PATCH v2 2/6] mm/balloon_compaction: keep ballooned pages away from normal migration path From: Konstantin Khlebnikov To: Andrew Morton Cc: Konstantin Khlebnikov , Rafael Aquini , Linux Kernel Mailing List , linux-mm@kvack.org, Andrey Ryabinin , Sasha Levin Date: Sat, 30 Aug 2014 20:41:13 +0400 Message-ID: <20140830164113.29066.25879.stgit@zurg> In-Reply-To: <20140830163834.29066.98205.stgit@zurg> References: <20140830163834.29066.98205.stgit@zurg> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Konstantin Khlebnikov Proper testing shows yet another problem in balloon migration: it works only once for each page. balloon_page_movable() check page flags and page_count. In __unmap_and_move page is locked, reference counter is elevated, so balloon_page_movable() _always_ fails here. As result in __unmap_and_move() migration goes to the normal migration path. Balloon ->migratepage() is so special, it returns MIGRATEPAGE_BALLOON_SUCCESS instead of MIGRATEPAGE_SUCCESS. After that in move_to_new_page() successfully migrated page got NULL into its mapping pointer and loses connectivity with balloon and ability for further migration. It's safe to use __is_movable_balloon_page here: page is isolated and pinned. Signed-off-by: Konstantin Khlebnikov Cc: stable # v3.8 --- include/linux/balloon_compaction.h | 5 +++++ mm/migrate.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h index 53d482e..284fc1d 100644 --- a/include/linux/balloon_compaction.h +++ b/include/linux/balloon_compaction.h @@ -258,6 +258,11 @@ static inline void balloon_page_delete(struct page *page) list_del(&page->lru); } +static inline bool __is_movable_balloon_page(struct page *page) +{ + return false; +} + static inline bool balloon_page_movable(struct page *page) { return false; diff --git a/mm/migrate.c b/mm/migrate.c index 905b1aa..57c94f9 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -873,7 +873,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage, } } - if (unlikely(balloon_page_movable(page))) { + if (unlikely(__is_movable_balloon_page(page))) { /* * A ballooned page does not need any special attention from * physical to virtual reverse mapping procedures.