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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CB81C433F5 for ; Thu, 3 Feb 2022 12:46:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BB5778D0148; Thu, 3 Feb 2022 07:46:34 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B64B48D0129; Thu, 3 Feb 2022 07:46:34 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A53AA8D0148; Thu, 3 Feb 2022 07:46:34 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0248.hostedemail.com [216.40.44.248]) by kanga.kvack.org (Postfix) with ESMTP id 96D978D0129 for ; Thu, 3 Feb 2022 07:46:34 -0500 (EST) Received: from smtpin31.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 501131823367B for ; Thu, 3 Feb 2022 12:46:34 +0000 (UTC) X-FDA: 79101442308.31.570A7BA Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf06.hostedemail.com (Postfix) with ESMTP id D2509180004 for ; Thu, 3 Feb 2022 12:46:33 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 9E94E1F399; Thu, 3 Feb 2022 12:46:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1643892392; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=WD0KsuFGAKxwPJ8TEDz3MZAplll7b1MiXcSJo4CExx4=; b=CQmLudPTvW4RaIzlWaw2EchZq5DbsHcpikxLxdiNyQzFdoT3+nVxC9O6xi3q9rw27Ye6Lp 7ygFDsjVCbZNeC2UEUGl9dY/9Gcry845qVzIqZPWuHDHO0NJgA4S862fpTyluqIeFsoRn4 p7lD24R7/HNiHwa1VlivOZxKVRNMnAQ= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 2F23CA3B92; Thu, 3 Feb 2022 12:46:32 +0000 (UTC) Date: Thu, 3 Feb 2022 13:46:31 +0100 From: Michal Hocko To: Waiman Long Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Petr Mladek , Steven Rostedt , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Ira Weiny , Mike Rapoport , David Rientjes , Roman Gushchin , Rafael Aquini Subject: Re: [PATCH v4 3/4] mm/page_owner: Print memcg information Message-ID: References: <20220131192308.608837-5-longman@redhat.com> <20220202203036.744010-4-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220202203036.744010-4-longman@redhat.com> X-Stat-Signature: 9f4ukuco8wc7sfy7g8ena61f5mjfzzdp X-Rspam-User: nil Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=CQmLudPT; spf=pass (imf06.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: D2509180004 X-HE-Tag: 1643892393-440069 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 Wed 02-02-22 15:30:35, Waiman Long wrote: [...] > +#ifdef CONFIG_MEMCG > + unsigned long memcg_data; > + struct mem_cgroup *memcg; > + bool online; > + char name[80]; > + > + rcu_read_lock(); > + memcg_data = READ_ONCE(page->memcg_data); > + if (!memcg_data) > + goto out_unlock; > + > + if (memcg_data & MEMCG_DATA_OBJCGS) > + ret += scnprintf(kbuf + ret, count - ret, > + "Slab cache page\n"); > + > + memcg = page_memcg_check(page); > + if (!memcg) > + goto out_unlock; > + > + online = (memcg->css.flags & CSS_ONLINE); > + cgroup_name(memcg->css.cgroup, name, sizeof(name)); Is there any specific reason to use another buffer allocated on the stack? Also 80B seems too short to cover NAME_MAX. Nothing else jumped at me. -- Michal Hocko SUSE Labs