From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by kanga.kvack.org (Postfix) with ESMTP id EBBB68E0001 for ; Tue, 18 Dec 2018 09:22:43 -0500 (EST) Received: by mail-ed1-f70.google.com with SMTP id 39so4061852edq.13 for ; Tue, 18 Dec 2018 06:22:43 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id l13si714908edw.439.2018.12.18.06.22.41 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 18 Dec 2018 06:22:42 -0800 (PST) Date: Tue, 18 Dec 2018 15:22:39 +0100 From: Michal Hocko Subject: Re: [PATCH V4 0/3] * mm/kvm/vfio/ppc64: Migrate compound pages out of CMA region Message-ID: <20181218142239.GL30879@dhcp22.suse.cz> References: <20181121092259.16482-1-aneesh.kumar@linux.ibm.com> <20181207151226.cb00ace433738cf550e66885@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181207151226.cb00ace433738cf550e66885@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: "Aneesh Kumar K.V" , 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 On Fri 07-12-18 15:12:26, Andrew Morton wrote: > 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.. I will unlikely find some time before the end of the year. Sorry about that. -- Michal Hocko SUSE Labs