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 6B9ACC2BBD5 for ; Fri, 18 Dec 2020 09:43:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 02E8223A80 for ; Fri, 18 Dec 2020 09:43:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02E8223A80 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7B1B56B005C; Fri, 18 Dec 2020 04:43:28 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 73A4D6B005D; Fri, 18 Dec 2020 04:43:28 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 629B86B0068; Fri, 18 Dec 2020 04:43:28 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0157.hostedemail.com [216.40.44.157]) by kanga.kvack.org (Postfix) with ESMTP id 49EFA6B005C for ; Fri, 18 Dec 2020 04:43:28 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 05C848249980 for ; Fri, 18 Dec 2020 09:43:28 +0000 (UTC) X-FDA: 77605915296.27.able05_4e184712743c Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin27.hostedemail.com (Postfix) with ESMTP id E0D683D663 for ; Fri, 18 Dec 2020 09:43:27 +0000 (UTC) X-HE-Tag: able05_4e184712743c X-Filterd-Recvd-Size: 2820 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Fri, 18 Dec 2020 09:43:27 +0000 (UTC) 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=1608284606; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Kns51nghtkz6ndAww0GyVqmKXCNEXcevy0MsQVndr/Q=; b=BeXlxK9M4wgEVguLtRScCNhQjzll21viDpb7mjSOySSiwfuIAFOm6LrI5elHH55KfG81Qf t2uxwmdt6qwwCserYXTFBNQKHazYMkB5euGcVgHvByC/5JFQlY3mt5eyvJl7ihJWVtnK4X 63LP2G/AU+lJ0CBSxgu5n2vySg4Nto0= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 29927ACC4; Fri, 18 Dec 2020 09:43:26 +0000 (UTC) Date: Fri, 18 Dec 2020 10:43:24 +0100 From: Michal Hocko To: Pavel Tatashin Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz, david@redhat.com, osalvador@suse.de, dan.j.williams@intel.com, sashal@kernel.org, tyhicks@linux.microsoft.com, iamjoonsoo.kim@lge.com, mike.kravetz@oracle.com, rostedt@goodmis.org, mingo@redhat.com, jgg@ziepe.ca, peterz@infradead.org, mgorman@suse.de, willy@infradead.org, rientjes@google.com, jhubbard@nvidia.com, linux-doc@vger.kernel.org, ira.weiny@intel.com, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v4 05/10] mm/gup: migrate pinned pages out of movable zone Message-ID: <20201218094324.GT32193@dhcp22.suse.cz> References: <20201217185243.3288048-1-pasha.tatashin@soleen.com> <20201217185243.3288048-6-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201217185243.3288048-6-pasha.tatashin@soleen.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu 17-12-20 13:52:38, Pavel Tatashin wrote: > + * 1. Pinned pages: (long-term) pinning of movable pages is avoided > + * when pages are pinned and faulted, but it is still possible that > + * address space already has pages in ZONE_MOVABLE at the time when > + * pages are pinned (i.e. user has touches that memory before > + * pinning). In such case we try to migrate them to a different zone, > + * but if migration fails the pages can still end-up pinned in > + * ZONE_MOVABLE. In such case, memory offlining might retry a long > + * time and will only succeed once user application unpins pages. I still dislike this. Pinning can fail so there shouldn't be any reasons to break MOVABLE constrain for something that can be handled. If anything there should be a very good reasoning behind this decision documented. -- Michal Hocko SUSE Labs