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=-5.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 966E6C4332D for ; Fri, 20 Mar 2020 02:20:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 37FDB20752 for ; Fri, 20 Mar 2020 02:20:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HGUbvFqh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 37FDB20752 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9F6686B0003; Thu, 19 Mar 2020 22:20:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9A7136B0006; Thu, 19 Mar 2020 22:20:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 896A36B0007; Thu, 19 Mar 2020 22:20:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0103.hostedemail.com [216.40.44.103]) by kanga.kvack.org (Postfix) with ESMTP id 6F9036B0003 for ; Thu, 19 Mar 2020 22:20:51 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 58FEA52AC for ; Fri, 20 Mar 2020 02:20:51 +0000 (UTC) X-FDA: 76614137502.01.bed11_7bd349a224a35 X-HE-Tag: bed11_7bd349a224a35 X-Filterd-Recvd-Size: 4628 Received: from mail-pf1-f193.google.com (mail-pf1-f193.google.com [209.85.210.193]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Fri, 20 Mar 2020 02:20:50 +0000 (UTC) Received: by mail-pf1-f193.google.com with SMTP id z5so2457960pfn.5 for ; Thu, 19 Mar 2020 19:20:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=cPwM+QqNlgDPzxplztv7TrYXYEhcBAjbWyampL91/uk=; b=HGUbvFqhhBa7RXlUkkm/9LbqglDlfAEKky6tzlTpkF7+WdvGTNelcFWM/KEPFWXtdl TOVxZrRzdZpYRxfrtRnTG756AE0O0YcJWbKhdj6dZmbpVVo3uX5Fv4Lkbi9HzPBfyzD+ 3OOeGdASpzl+//K6oHf0jiRovGhl6oNXSN0wjqRoIZFMl5XtnawLIGSl1qv2sg4SDyoX 0/GaM90mMs1FBpUI30CFjVwEWk9ma4bTM538zZv9W1Jnhq8oj+csZcHfsXmawHY0GCOa K/2gS/DahThLLfHrynscEWzZuDM3JjD6lDpMh67zjO0FUE7qrFj6VBP5a80avhSoN/SU wrxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=cPwM+QqNlgDPzxplztv7TrYXYEhcBAjbWyampL91/uk=; b=oLWbaropttFse5mofqV6HYa0GbBj+rfxnW8JngfGPb62TIB6KAMQQ35BttKGuL0iao IHB5kN/HOkInVCKllo1tBMHigdMTYTxsSuFlItXaqKDTwKxpzKGjnAOVHUULHTAeoBN2 tyfmxy7wAT7XlGgzjIyw4t6hICgENv7sXK48T860y6aOWors4ZNIg9rLO68X6+aZEuoZ 70Z/7OunHQ1WADBj1RFctSxjgObsz+UN6Kd+/M9Z66ArEFKYm4C1j+NuOlZCQB2Mn3Jh qWn2LT6YY91B9nHmK9TeoLYccB6mZKOsRBBfvhyreXUXda6yTsHqMIdn/sPhUrsrzkta MxEQ== X-Gm-Message-State: ANhLgQ0MfHwK58Q/QdAEgLIqsC3Hm4wfmC/W7RZyg3Pd9iHEoN2VOD/5 deYICI+bG72vVGMa/v+VwMo= X-Google-Smtp-Source: ADFU+vv7ArjaniwbQSiqPhmYixYjtAuGiR9o/6NIDsHLTThcIDEBYDxc6V8EXug3EF9lqhY9tNAh7Q== X-Received: by 2002:aa7:8642:: with SMTP id a2mr7417204pfo.60.1584670849506; Thu, 19 Mar 2020 19:20:49 -0700 (PDT) Received: from localhost ([43.224.245.179]) by smtp.gmail.com with ESMTPSA id t142sm3480770pgb.31.2020.03.19.19.20.48 (version=TLS1_2 cipher=AES128-SHA bits=128/128); Thu, 19 Mar 2020 19:20:49 -0700 (PDT) Date: Fri, 20 Mar 2020 10:20:46 +0800 From: chenqiwu To: Chris Down Cc: akpm@linux-foundation.org, linux-mm@kvack.org, chenqiwu Subject: Re: [PATCH] mm/vmscan: fix incorrect return type for cgroup_reclaim() Message-ID: <20200320022046.GA31830@cqw-OptiPlex-7050> References: <1584633026-26288-1-git-send-email-qiwuchen55@gmail.com> <20200319162025.GA237751@chrisdown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200319162025.GA237751@chrisdown.name> User-Agent: Mutt/1.5.21 (2010-09-15) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000186, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 19, 2020 at 04:20:25PM +0000, Chris Down wrote: > qiwuchen55@gmail.com writes: > >From: chenqiwu > > > >The return type of cgroup_reclaim() is bool, but the correct type > >should be struct mem_cgroup pointer. As a result, cgroup_reclaim() > >can be used to wrap sc->target_mem_cgroup in vmscan code. > > The code changes looks okay to me, but the changelog and patch > subject could do with some improvement. For example, the type isn't > "incorrect" before and "correct" now, per se, it's just coercing > from *struct mem_cgroup to bool. > > Could you make it more clear what your intent is in the patch? If > it's that you found the code confusing, you can just write something > like: > > mm/vmscan: return target_mem_cgroup from cgroup_reclaim > > Previously the code splits apart the action of checking whether > we are in cgroup reclaim from getting the target memory cgroup > for that reclaim. This split is confusing and seems unnecessary, > since cgroup_reclaim itself only checks if sc->target_mem_cgroup > is NULL or not, so merge the two use cases into one by returning > the target_mem_cgroup itself from cgroup_reclaim. > > >Signed-off-by: chenqiwu > > After improving the patch title and summary, you can add: > > Acked-by: Chris Down > Hi Chris, Thanks for your review. I will resend this as patch v2. BTW, sc->target_mem_cgroup is just used when CONFIG_MEMCG=y, so wrap it with config CONFIG_MEMCG will save some space for those who build their kernels with cgroups disabled. Qiwu