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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 B819DC433E0 for ; Mon, 1 Feb 2021 15:19:32 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2D8A564EA0 for ; Mon, 1 Feb 2021 15:19:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D8A564EA0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6FDB16B0005; Mon, 1 Feb 2021 10:19:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6861A6B006C; Mon, 1 Feb 2021 10:19:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 526D96B006E; Mon, 1 Feb 2021 10:19:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0146.hostedemail.com [216.40.44.146]) by kanga.kvack.org (Postfix) with ESMTP id 390866B0005 for ; Mon, 1 Feb 2021 10:19:31 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id D96313622 for ; Mon, 1 Feb 2021 15:19:30 +0000 (UTC) X-FDA: 77770058100.20.ocean35_2f12beb275c3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id 5B12F1801AAA7 for ; Mon, 1 Feb 2021 15:17:54 +0000 (UTC) X-HE-Tag: ocean35_2f12beb275c3 X-Filterd-Recvd-Size: 2586 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Mon, 1 Feb 2021 15:17:53 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 46D07AD18; Mon, 1 Feb 2021 15:17:52 +0000 (UTC) Subject: Re: [v5 PATCH 07/11] mm: vmscan: add per memcg shrinker nr_deferred To: Yang Shi Cc: Roman Gushchin , Kirill Tkhai , Shakeel Butt , Dave Chinner , Johannes Weiner , Michal Hocko , Andrew Morton , Linux MM , Linux FS-devel Mailing List , Linux Kernel Mailing List References: <20210127233345.339910-1-shy828301@gmail.com> <20210127233345.339910-8-shy828301@gmail.com> <6b0638ba-2513-67f5-8ef1-9e60a7d9ded6@suse.cz> From: Vlastimil Babka Message-ID: <0ce8b6e4-5abb-3edb-8423-f6c222420a89@suse.cz> Date: Mon, 1 Feb 2021 16:17:51 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 1/29/21 7:04 PM, Yang Shi wrote: >> > > @@ -209,9 +214,15 @@ static int expand_one_shrinker_info(struct mem_cgroup *memcg, >> > > if (!new) >> > > return -ENOMEM; >> > > >> > > - /* Set all old bits, clear all new bits */ >> > > - memset(new->map, (int)0xff, old_size); >> > > - memset((void *)new->map + old_size, 0, size - old_size); >> > > + new->map = (unsigned long *)(new + 1); >> > > + new->nr_deferred = (void *)new->map + m_size; >> > >> > This better be aligned to sizeof(atomic_long_t). Can we be sure about that? >> >> Good point. No, if unsigned long is 32 bit on some 64 bit machines. > > I think we could just change map to "u64" and guarantee struct > shrinker_info is aligned to 64 bit. What about changing to order, nr_deferred before map? Then the atomics are at the beginning of allocated area, thus aligned.