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 F191AC43441 for ; Fri, 23 Nov 2018 12:44:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD67120672 for ; Fri, 23 Nov 2018 12:44:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BD67120672 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 S2409878AbeKWX2E (ORCPT ); Fri, 23 Nov 2018 18:28:04 -0500 Received: from mx2.suse.de ([195.135.220.15]:38132 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388147AbeKWX2E (ORCPT ); Fri, 23 Nov 2018 18:28:04 -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 624CCAEC0; Fri, 23 Nov 2018 12:43:59 +0000 (UTC) Date: Fri, 23 Nov 2018 13:43:58 +0100 From: Michal Hocko To: Daniel Vetter Cc: Daniel Vetter , LKML , Linux MM , Intel Graphics Development , DRI Development , Andrew Morton , Christian =?iso-8859-1?Q?K=F6nig?= , David Rientjes , =?iso-8859-1?B?Suly9G1l?= Glisse , Paolo Bonzini , Daniel Vetter Subject: Re: [PATCH 1/3] mm: Check if mmu notifier callbacks are allowed to fail Message-ID: <20181123124358.GJ8625@dhcp22.suse.cz> References: <20181122165106.18238-1-daniel.vetter@ffwll.ch> <20181122165106.18238-2-daniel.vetter@ffwll.ch> <20181123111557.GG8625@dhcp22.suse.cz> <20181123123057.GK4266@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181123123057.GK4266@phenom.ffwll.local> 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 Fri 23-11-18 13:30:57, Daniel Vetter wrote: > On Fri, Nov 23, 2018 at 12:15:57PM +0100, Michal Hocko wrote: > > On Thu 22-11-18 17:51:04, Daniel Vetter wrote: > > > Just a bit of paranoia, since if we start pushing this deep into > > > callchains it's hard to spot all places where an mmu notifier > > > implementation might fail when it's not allowed to. > > > > What does WARN give you more than the existing pr_info? Is really > > backtrace that interesting? > > Automated tools have to ignore everything at info level (there's too much > of that). I guess I could do something like > > if (blockable) > pr_warn(...) > else > pr_info(...) > > WARN() is simply my goto tool for getting something at warning level > dumped into dmesg. But I think the pr_warn with the callback function > should be enough indeed. I wouldn't mind s@pr_info@pr_warn@ > If you wonder where all the info level stuff happens that we have to > ignore: suspend/resume is a primary culprit (fairly important for > gfx/desktops), but there's a bunch of other places. Even if we ignore > everything at info and below we still need filters because some drivers > are a bit too trigger-happy (i915 definitely included I guess, so everyone > contributes to this problem). Thanks for the clarification. -- Michal Hocko SUSE Labs