From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752525AbeB0Hov (ORCPT ); Tue, 27 Feb 2018 02:44:51 -0500 Received: from mx2.suse.de ([195.135.220.15]:54831 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752475AbeB0Hot (ORCPT ); Tue, 27 Feb 2018 02:44:49 -0500 Subject: Re: [v2 1/1] xen, mm: Allow deferred page initialization for xen pv domains To: Pavel Tatashin , steven.sistare@oracle.com, daniel.m.jordan@oracle.com, akataria@vmware.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, boris.ostrovsky@oracle.com, akpm@linux-foundation.org, mhocko@suse.com, vbabka@suse.cz, luto@kernel.org, labbott@redhat.com, kirill.shutemov@linux.intel.com, bp@suse.de, minipli@googlemail.com, jinb.park7@gmail.com, dan.j.williams@intel.com, bhe@redhat.com, zhang.jia@linux.alibaba.com, mgorman@techsingularity.net, hannes@cmpxchg.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, linux-mm@kvack.org References: <20180226160112.24724-1-pasha.tatashin@oracle.com> <20180226160112.24724-2-pasha.tatashin@oracle.com> From: Juergen Gross Message-ID: <927f2a94-2ece-53f7-3be8-532f3be77dd4@suse.com> Date: Tue, 27 Feb 2018 08:44:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180226160112.24724-2-pasha.tatashin@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: de-DE Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/02/18 17:01, Pavel Tatashin wrote: > Juergen Gross noticed that commit > f7f99100d8d ("mm: stop zeroing memory during allocation in vmemmap") > broke XEN PV domains when deferred struct page initialization is enabled. > > This is because the xen's PagePinned() flag is getting erased from struct > pages when they are initialized later in boot. > > Juergen fixed this problem by disabling deferred pages on xen pv domains. > It is desirable, however, to have this feature available as it reduces boot > time. This fix re-enables the feature for pv-dmains, and fixes the problem > the following way: > > The fix is to delay setting PagePinned flag until struct pages for all > allocated memory are initialized, i.e. until after free_all_bootmem(). > > A new x86_init.hyper op init_after_bootmem() is called to let xen know > that boot allocator is done, and hence struct pages for all the allocated > memory are now initialized. If deferred page initialization is enabled, the > rest of struct pages are going to be initialized later in boot once > page_alloc_init_late() is called. > > xen_after_bootmem() walks page table's pages and marks them pinned. > > Signed-off-by: Pavel Tatashin Verified to work on a system where the original issue caused a crash. Reviewed-by: Juergen Gross Tested-by: Juergen Gross Juergen