From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751851AbbCTNpo (ORCPT ); Fri, 20 Mar 2015 09:45:44 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:17824 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750992AbbCTNpn (ORCPT ); Fri, 20 Mar 2015 09:45:43 -0400 Message-ID: <550C2422.6060409@oracle.com> Date: Fri, 20 Mar 2015 09:44:02 -0400 From: Boris Ostrovsky User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Juergen Gross , linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, konrad.wilk@oracle.com, david.vrabel@citrix.com, daniel.kiper@oracle.com, pebolle@tiscali.nl Subject: Re: [Patch V2 2/2] xen: before ballooning hotplugged memory, set frames to invalid References: <1426856139-3359-1-git-send-email-jgross@suse.com> <1426856139-3359-3-git-send-email-jgross@suse.com> In-Reply-To: <1426856139-3359-3-git-send-email-jgross@suse.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/20/2015 08:55 AM, Juergen Gross wrote: > Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set > regions above the end of RAM as 1:1") introduced a regression. > > To be able to add memory pages which were added via memory hotplug to > a pv domain, the pages must be "invalid" instead of "identity" in the > p2m list before they can be added. > > Suggested-by: David Vrabel > Signed-off-by: Juergen Gross > --- > drivers/xen/balloon.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c > index 0b52d92..65fedb8 100644 > --- a/drivers/xen/balloon.c > +++ b/drivers/xen/balloon.c > @@ -229,6 +229,19 @@ static enum bp_state reserve_additional_memory(long credit) > balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION); > nid = memory_add_physaddr_to_nid(hotplug_start_paddr); > > +#ifdef CONFIG_XEN_HAVE_PVMMU > + if (!xen_feature(XENFEAT_auto_translated_physmap)) { > + unsigned long pfn, i; > + > + pfn = PFN_DOWN(hotplug_start_paddr); > + for (i = 0; i < balloon_hotplug; i++) > + if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) { > + pr_warn("set_phys_to_machine() failed, no memory added\n"); > + return BP_ECANCELED; I should have asked last time --- should we restore [0..i-1] mapping back to identity on error here? I wonder whether leaving those frames as invalid (when they are expected to be 'identity') could cause problems in the future. -boris > + } > + } > +#endif > + > rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug << PAGE_SHIFT); > > if (rc) {