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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 8A624C43441 for ; Tue, 27 Nov 2018 16:29:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 43B3A2086B for ; Tue, 27 Nov 2018 16:29:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 43B3A2086B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 S1731044AbeK1D1p (ORCPT ); Tue, 27 Nov 2018 22:27:45 -0500 Received: from mx2.suse.de ([195.135.220.15]:59276 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726768AbeK1D1p (ORCPT ); Tue, 27 Nov 2018 22:27:45 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 8BB4AAB6D; Tue, 27 Nov 2018 16:29:17 +0000 (UTC) Date: Tue, 27 Nov 2018 17:29:16 +0100 From: Michal Hocko To: Heiko Carstens Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-mm@kvack.org, "Kirill A . Shutemov" , Martin Schwidefsky Subject: Re: [PATCH] mm: warn only once if page table misaccounting is detected Message-ID: <20181127162916.GB6923@dhcp22.suse.cz> References: <20181127083603.39041-1-heiko.carstens@de.ibm.com> <20181127131916.GX12455@dhcp22.suse.cz> <20181127143638.GE3625@osiris> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181127143638.GE3625@osiris> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 27-11-18 15:36:38, Heiko Carstens wrote: > On Tue, Nov 27, 2018 at 02:19:16PM +0100, Michal Hocko wrote: > > On Tue 27-11-18 09:36:03, Heiko Carstens wrote: > > > Use pr_alert_once() instead of pr_alert() if page table misaccounting > > > has been detected. > > > > > > If this happens once it is very likely that there will be numerous > > > other occurrence as well, which would flood dmesg and the console with > > > hardly any added information. Therefore print the warning only once. > > > > Have you actually experience a flood of these messages? Is one per mm > > message really that much? > > Yes, I did. Since in this case all compat processes caused the message > to appear, I saw thousands of these messages. This means something went colossally wrong and seeing an avalanche of messages might be actually helpful because you can at least see the pattern. I wonder whether the underlying issue would be obvious from a single instance. Maybe we want ratelimit instead? > > If yes why rss counters do not exhibit the same problem? > > No rss counter messages appeared. Or do you suggest that the other > pr_alert() within check_mm() should also be changed? Whatever we go with (and I do not have a strong opinion here) we should be consistent I believe. -- Michal Hocko SUSE Labs