From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by kanga.kvack.org (Postfix) with ESMTP id EA6C06B4905 for ; Tue, 27 Nov 2018 11:29:19 -0500 (EST) Received: by mail-ed1-f69.google.com with SMTP id c3so11248090eda.3 for ; Tue, 27 Nov 2018 08:29:19 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id b6si33995edc.315.2018.11.27.08.29.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Nov 2018 08:29:17 -0800 (PST) Date: Tue, 27 Nov 2018 17:29:16 +0100 From: Michal Hocko 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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