Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758721Ab2FUIOO (ORCPT ); Thu, 21 Jun 2012 04:14:14 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:52517 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754488Ab2FUIOK (ORCPT ); Thu, 21 Jun 2012 04:14:10 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <4FE2D747.20506@jp.fujitsu.com> Date: Thu, 21 Jun 2012 17:11:51 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.0; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Andrew Morton CC: linux-mm , Linux Kernel Mailing List , cgroups@vger.kernel.org, Michal Hocko , Johannes Weiner Subject: Re: [PATCH 2/2] memcg: clean up force_empty_list() return value check References: <4FDF17A3.9060202@jp.fujitsu.com> <4FDF1830.1000504@jp.fujitsu.com> <20120619165815.5ce24be7.akpm@linux-foundation.org> In-Reply-To: <20120619165815.5ce24be7.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2705 Lines: 89 (2012/06/20 8:58), Andrew Morton wrote: > On Mon, 18 Jun 2012 20:59:44 +0900 > Kamezawa Hiroyuki wrote: > >> >> By commit "memcg: move charges to root cgroup if use_hierarchy=0" >> mem_cgroup_move_parent() only returns -EBUSY, -EINVAL. >> So, we can remove -ENOMEM and -EINTR checks. >> >> Signed-off-by: KAMEZAWA Hiroyuki >> --- >> mm/memcontrol.c | 5 ----- >> 1 files changed, 0 insertions(+), 5 deletions(-) >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index cf8a0f6..726b7c6 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -3847,8 +3847,6 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg, >> pc = lookup_page_cgroup(page); >> >> ret = mem_cgroup_move_parent(page, pc, memcg, GFP_KERNEL); >> - if (ret == -ENOMEM || ret == -EINTR) >> - break; >> >> if (ret == -EBUSY || ret == -EINVAL) { > > This looks a bit fragile - if mem_cgroup_move_parent() is later changed > (intentionally or otherwise!) to return -Esomethingelse then > mem_cgroup_force_empty_list() will subtly break. Why not just do > > if (ret< 0) > You're right. I'm sorry I haven't done enough clean-ups. I made 2 more patches...I'll repost/remake all paches if it's better. one more patch will follow this email. == From eee5f31fc6378da19705de7187bb3f219ef6d7f6 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Thu, 21 Jun 2012 17:25:04 +0900 Subject: [PATCH 1/2] mem_cgroup_move_parent() doesn't need gfp_mask. Signed-off-by: KAMEZAWA Hiroyuki --- mm/memcontrol.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 76d83a5..90a2ad4 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2662,8 +2662,7 @@ out: static int mem_cgroup_move_parent(struct page *page, struct page_cgroup *pc, - struct mem_cgroup *child, - gfp_t gfp_mask) + struct mem_cgroup *child) { struct mem_cgroup *parent; unsigned int nr_pages; @@ -3837,7 +3836,7 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg, pc = lookup_page_cgroup(page); - ret = mem_cgroup_move_parent(page, pc, memcg, GFP_KERNEL); + ret = mem_cgroup_move_parent(page, pc, memcg); if (ret == -EBUSY || ret == -EINVAL) { /* found lock contention or "pc" is obsolete. */ -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/