From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751813AbdJXObl (ORCPT ); Tue, 24 Oct 2017 10:31:41 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:38270 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750908AbdJXObj (ORCPT ); Tue, 24 Oct 2017 10:31:39 -0400 Subject: Re: [PATCH] xen: fix booting ballooned down hvm guest To: Juergen Gross , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org References: <20171024081050.2441-1-jgross@suse.com> Cc: hw42@ipsumj.de, stable@vger.kernel.org From: Boris Ostrovsky Message-ID: <554ab545-5e74-29c8-0eb7-5db1dcbeb6bb@oracle.com> Date: Tue, 24 Oct 2017 10:33:07 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20171024081050.2441-1-jgross@suse.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/24/2017 04:10 AM, Juergen Gross wrote: > Commit 96edd61dcf44362d3ef0bed1a5361e0ac7886a63 ("xen/balloon: don't > online new memory initially") introduced a regression when booting a > HVM domain with memory less than mem-max: instead of ballooning down > immediately the system would try to use the memory up to mem-max > resulting in Xen crashing the domain. > > For HVM domains the current size will be reflected in Xenstore node > memory/static-max instead of memory/target. > > Additionally we have to trigger the ballooning process at once. > > Cc: # 4.13 > Fixes: 96edd61dcf44362d3ef0bed1a5361e0ac7886a63 ("xen/balloon: don't > online new memory initially") > > Suggested-by: Boris Ostrovsky > Signed-off-by: Juergen Gross Reported-by: HW42 > --- > drivers/xen/xen-balloon.c | 18 ++++++++++++------ > 1 file changed, 12 insertions(+), 6 deletions(-) > > diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c > index e89136ab851e..3745748d9644 100644 > --- a/drivers/xen/xen-balloon.c > +++ b/drivers/xen/xen-balloon.c > @@ -57,7 +57,7 @@ static int register_balloon(struct device *dev); > static void watch_target(struct xenbus_watch *watch, > const char *path, const char *token) > { > - unsigned long long new_target; > + unsigned long long new_target, static_max; > int err; > static bool watch_fired; > static long target_diff; > @@ -72,13 +72,19 @@ static void watch_target(struct xenbus_watch *watch, > * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. > */ > new_target >>= PAGE_SHIFT - 10; > - if (watch_fired) { > - balloon_set_new_target(new_target - target_diff); > - return; > + > + if (!watch_fired) { > + watch_fired = true; > + err = xenbus_scanf(XBT_NIL, "memory", "static-max", "%llu", > + &static_max); > + if (err != 1) > + static_max = new_target; > + static_max >>= PAGE_SHIFT - 10; if you set static_max to new_target you've already done the shift, haven't you? > + target_diff = xen_pv_domain() ? 0 Why do we special-case PV? -boris > + : static_max - balloon_stats.target_pages; > } > > - watch_fired = true; > - target_diff = new_target - balloon_stats.target_pages; > + balloon_set_new_target(new_target - target_diff); > } > static struct xenbus_watch target_watch = { > .node = "memory/target",