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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 D2816C07E85 for ; Fri, 7 Dec 2018 23:12:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8AE9D20838 for ; Fri, 7 Dec 2018 23:12:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8AE9D20838 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.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 S1726105AbeLGXM2 (ORCPT ); Fri, 7 Dec 2018 18:12:28 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:55712 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726041AbeLGXM2 (ORCPT ); Fri, 7 Dec 2018 18:12:28 -0500 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id E7DED89C; Fri, 7 Dec 2018 23:12:26 +0000 (UTC) Date: Fri, 7 Dec 2018 15:12:26 -0800 From: Andrew Morton To: "Aneesh Kumar K.V" Cc: Michal Hocko , Alexey Kardashevskiy , mpe@ellerman.id.au, paulus@samba.org, David Gibson , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH V4 0/3] * mm/kvm/vfio/ppc64: Migrate compound pages out of CMA region Message-Id: <20181207151226.cb00ace433738cf550e66885@linux-foundation.org> In-Reply-To: <20181121092259.16482-1-aneesh.kumar@linux.ibm.com> References: <20181121092259.16482-1-aneesh.kumar@linux.ibm.com> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 21 Nov 2018 14:52:56 +0530 "Aneesh Kumar K.V" wrote: > Subject: [PATCH V4 0/3] * mm/kvm/vfio/ppc64: Migrate compound pages out of CMA region Asterisk in title is strange? > ppc64 use CMA area for the allocation of guest page table (hash page table). We won't > be able to start guest if we fail to allocate hash page table. We have observed > hash table allocation failure because we failed to migrate pages out of CMA region > because they were pinned. This happen when we are using VFIO. VFIO on ppc64 pins > the entire guest RAM. If the guest RAM pages get allocated out of CMA region, we > won't be able to migrate those pages. The pages are also pinned for the lifetime of the > guest. > > Currently we support migration of non-compound pages. With THP and with the addition of > hugetlb migration we can end up allocating compound pages from CMA region. This > patch series add support for migrating compound pages. The first path adds the helper > get_user_pages_cma_migrate() which pin the page making sure we migrate them out of > CMA region before incrementing the reference count. Very little review activity. Perhaps Andrey and/or Michal can find the time.. > mm/migrate.c | 108 ++++++++++++++++++++++++++++++++++++++++ can we make this code disappear when CONFIG_CMA=n?