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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 27BCAC4361B for ; Mon, 14 Dec 2020 14:31:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DA4942222B for ; Mon, 14 Dec 2020 14:31:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437234AbgLNObh (ORCPT ); Mon, 14 Dec 2020 09:31:37 -0500 Received: from mx2.suse.de ([195.135.220.15]:50770 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727309AbgLNObW (ORCPT ); Mon, 14 Dec 2020 09:31:22 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1607956229; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VUY6eHvF0hm7t3R1gw9rif3wuaCt6bfVpTqXElvOz3M=; b=Y7X6h872zSTm3SEcrwaV2YbCYszx3s2DSHO4VzfOLxaTCQOSakvdkAG9BC16HWzgbuuH0F XtyTJxb4nVjHkyBFbSaJsRZEj5jtl69FipuB3oXqfpFeqA2Bs9JE7/hXg+5NVoRbvKb36n ogIopudl0LUiMzt6KdQZCjIUOosflE4= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id AEA76AFA7; Mon, 14 Dec 2020 14:30:28 +0000 (UTC) Date: Mon, 14 Dec 2020 15:30:27 +0100 From: Michal Hocko To: David Hildenbrand Cc: Jason Gunthorpe , Pavel Tatashin , LKML , linux-mm , Andrew Morton , Vlastimil Babka , Oscar Salvador , Dan Williams , Sasha Levin , Tyler Hicks , Joonsoo Kim , mike.kravetz@oracle.com, Steven Rostedt , Ingo Molnar , Peter Zijlstra , Mel Gorman , Matthew Wilcox , David Rientjes , John Hubbard , Linux Doc Mailing List Subject: Re: [PATCH v3 5/6] mm/gup: migrate pinned pages out of movable zone Message-ID: <20201214143027.GH32193@dhcp22.suse.cz> References: <20201211235005.GE5487@ziepe.ca> <2D10D596-3159-483C-81B4-CD187806ED46@redhat.com> <20201214133603.GF5487@ziepe.ca> <69beec6b-8518-aa47-5a08-fd5f85cf9430@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <69beec6b-8518-aa47-5a08-fd5f85cf9430@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 14-12-20 15:21:21, David Hildenbrand wrote: > On 14.12.20 14:36, Jason Gunthorpe wrote: > > On Sat, Dec 12, 2020 at 08:29:11AM +0100, David Hildenbrand wrote: > > > >>> Racing with another GUP in another thread is also not reasonable, so > >>> failing to isolate can't be a failure > >> > >> Having VMs with multiple vfio containers is certainly realistic, and > >> optimizing in user space to do vfio mappings concurrently doesn‘t > >> sound too crazy to me. But I haven‘t checked if vfio common code > >> already handles such concurrency. > > > > There is a lot more out there than vfio.. RDMA already does concurrent > > pin_user_pages in real apps > > I actually misread your comment. I think we both agree that temporary > isolation failures must not lead to a failure. Yes, isolation failures are ephemeral. I believe that the migration should start distinguishing between these and hard failures. -- Michal Hocko SUSE Labs