From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6C48C04EB9 for ; Mon, 3 Dec 2018 14:49:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A90020848 for ; Mon, 3 Dec 2018 14:49:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7A90020848 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726656AbeLCOur (ORCPT ); Mon, 3 Dec 2018 09:50:47 -0500 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:43483 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726116AbeLCOur (ORCPT ); Mon, 3 Dec 2018 09:50:47 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R501e4;CH=green;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01429;MF=xlpang@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0TElAQiJ_1543848559; Received: from xunleideMacBook-Pro.local(mailfrom:xlpang@linux.alibaba.com fp:SMTPD_---0TElAQiJ_1543848559) by smtp.aliyun-inc.com(127.0.0.1); Mon, 03 Dec 2018 22:49:19 +0800 Reply-To: xlpang@linux.alibaba.com Subject: Re: [PATCH 1/3] mm/memcg: Fix min/low usage in propagate_protected_usage() To: Michal Hocko Cc: Roman Gushchin , Johannes Weiner , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20181203080119.18989-1-xlpang@linux.alibaba.com> <20181203115453.GO31738@dhcp22.suse.cz> From: Xunlei Pang Message-ID: <1c62ec71-52de-3597-ec87-3dd8d81c4d2a@linux.alibaba.com> Date: Mon, 3 Dec 2018 22:49:18 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:60.0) Gecko/20100101 Thunderbird/60.3.2 MIME-Version: 1.0 In-Reply-To: <20181203115453.GO31738@dhcp22.suse.cz> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/12/3 ÏÂÎç7:54, Michal Hocko wrote: > On Mon 03-12-18 16:01:17, Xunlei Pang wrote: >> When usage exceeds min, min usage should be min other than 0. >> Apply the same for low. > > Why? What is the actual problem. children_min_usage tracks the total children usages under min, it's natural that min should be added into children_min_usage when above min, I can't image why 0 is added, is there special history I missed? See mem_cgroup_protected(), when usage exceeds min, emin is calculated as "parent_emin*min/children_min_usage". > >> Signed-off-by: Xunlei Pang >> --- >> mm/page_counter.c | 12 ++---------- >> 1 file changed, 2 insertions(+), 10 deletions(-) >> >> diff --git a/mm/page_counter.c b/mm/page_counter.c >> index de31470655f6..75d53f15f040 100644 >> --- a/mm/page_counter.c >> +++ b/mm/page_counter.c >> @@ -23,11 +23,7 @@ static void propagate_protected_usage(struct page_counter *c, >> return; >> >> if (c->min || atomic_long_read(&c->min_usage)) { >> - if (usage <= c->min) >> - protected = usage; >> - else >> - protected = 0; >> - >> + protected = min(usage, c->min); >> old_protected = atomic_long_xchg(&c->min_usage, protected); >> delta = protected - old_protected; >> if (delta) >> @@ -35,11 +31,7 @@ static void propagate_protected_usage(struct page_counter *c, >> } >> >> if (c->low || atomic_long_read(&c->low_usage)) { >> - if (usage <= c->low) >> - protected = usage; >> - else >> - protected = 0; >> - >> + protected = min(usage, c->low); >> old_protected = atomic_long_xchg(&c->low_usage, protected); >> delta = protected - old_protected; >> if (delta) >> -- >> 2.13.5 (Apple Git-94) >> >