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 B8D32C43441 for ; Fri, 23 Nov 2018 11:14:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7691F20659 for ; Fri, 23 Nov 2018 11:14:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7691F20659 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 S2503647AbeKWV6V (ORCPT ); Fri, 23 Nov 2018 16:58:21 -0500 Received: from mx2.suse.de ([195.135.220.15]:53110 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2409552AbeKWV6V (ORCPT ); Fri, 23 Nov 2018 16:58:21 -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 4CE5BAD93; Fri, 23 Nov 2018 11:14:29 +0000 (UTC) Date: Fri, 23 Nov 2018 12:14:28 +0100 From: Michal Hocko To: Daniel Vetter Cc: Chris Wilson , Daniel Vetter , LKML , Daniel Vetter , Intel Graphics Development , DRI Development , Linux MM , =?iso-8859-1?B?Suly9G1l?= Glisse , David Rientjes , Paolo Bonzini , Andrew Morton , Christian =?iso-8859-1?Q?K=F6nig?= Subject: Re: [Intel-gfx] [PATCH 1/3] mm: Check if mmu notifier callbacks are allowed to fail Message-ID: <20181123111428.GF8625@dhcp22.suse.cz> References: <20181122165106.18238-1-daniel.vetter@ffwll.ch> <20181122165106.18238-2-daniel.vetter@ffwll.ch> <154290561362.11623.15299444358726283678@skylake-alporthouse-com> <20181123084934.GI4266@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181123084934.GI4266@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 09:49:34, Daniel Vetter wrote: > On Thu, Nov 22, 2018 at 04:53:34PM +0000, Chris Wilson wrote: > > Quoting Daniel Vetter (2018-11-22 16:51:04) > > > 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. > > > > Most callers could handle the failure correctly. It looks like the > > failure was not propagated for convenience. > > I have no idea whether the mm is semantically ok if pte shootdown doesn't > work for all sorts of strange reasons. From the commit that introduced the > error code it souded like this was very much only ok in the limited case > of an already killed process, in the oom killer path, where it's really > only about trying to free any kind of memory. And where the process is > gone already, so semantics of what exactly happens don't matter that much > anymore. Yes this was indeed the case. There is still the exit path which would do the rest of the work so we are not leaving anything behind. -- Michal Hocko SUSE Labs