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 27E6CC433F5 for ; Tue, 8 Feb 2022 15:15:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A3EE96B0073; Tue, 8 Feb 2022 10:15:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9ED046B0074; Tue, 8 Feb 2022 10:15:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 88E416B0075; Tue, 8 Feb 2022 10:15:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0186.hostedemail.com [216.40.44.186]) by kanga.kvack.org (Postfix) with ESMTP id 770816B0073 for ; Tue, 8 Feb 2022 10:15:08 -0500 (EST) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 373FC824C421 for ; Tue, 8 Feb 2022 15:15:08 +0000 (UTC) X-FDA: 79119960696.23.62695D0 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf31.hostedemail.com (Postfix) with ESMTP id A188720007 for ; Tue, 8 Feb 2022 15:15:07 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 423561F383; Tue, 8 Feb 2022 15:15:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1644333306; 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=iIBn4Rav1LBR3y1c5hDMynQtqqgJZkX7I4kc9wq3uRs=; b=GsdnHU3cwdGn8OVGCJqWUbt20HF/QLQRsCFXZSmYmHY+SdULFqDf9IupBsQHpwsFqVyVQN Gf+fXxoyvKtpXIKaNdc14frKvMo3qSkwkkXPgfEDDToghZmni984WZ8/2vUDKVj61efMNJ iq6cAZzQVWGnl0xMx12l/0sRp5UgpnA= 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 CEED9A3B92; Tue, 8 Feb 2022 15:15:05 +0000 (UTC) Date: Tue, 8 Feb 2022 16:15:05 +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 , Mike Rapoport Subject: Re: [PATCH v5 3/4] mm/page_owner: Print memcg information Message-ID: References: <20220208000532.1054311-1-longman@redhat.com> <20220208000532.1054311-4-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=GsdnHU3c; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf31.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com X-Rspamd-Server: rspam03 X-Rspam-User: X-Stat-Signature: 9dipt6zwr7iq5jyokeywezu9tj4453ec X-Rspamd-Queue-Id: A188720007 X-HE-Tag: 1644333307-527782 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 Tue 08-02-22 13:13:15, Michal Hocko wrote: > On Mon 07-02-22 19:05:31, Waiman Long wrote: [...] > > + ret += scnprintf(kbuf + ret, count - ret, "\n"); > > I do not see any overflow prevention here. I believe you really need to > check ret >= count after each scnprintf/cgroup_name. OK, I have only now realized that scnprintf would return size - 1 on overflow so explicitly checking for the overlow shouldn't be reallu necessary. -- Michal Hocko SUSE Labs