From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: Xen crashing when killing a domain with no VCPUs allocated Date: Fri, 18 Jul 2014 21:26:39 +0100 Message-ID: <53C982FF.7070608@linaro.org> References: <53C920DD.6060300@linaro.org> <1405701560.14973.1.camel@kazak.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1405701560.14973.1.camel@kazak.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell Cc: jgross@suse.com, Stefano Stabellini , Dario Faggioli , Tim Deegan , george.dunlap@citrix.com, xen-devel List-Id: xen-devel@lists.xenproject.org On 18/07/14 17:39, Ian Campbell wrote: > On Fri, 2014-07-18 at 14:27 +0100, Julien Grall wrote: >> Hi all, >> >> I've been played with the function alloc_vcpu on ARM. And I hit one case >> where this function can failed. >> >> During domain creation, the toolstack will call DOMCTL_max_vcpus which may >> fail, for instance because alloc_vcpu didn't succeed. In this case, the >> toolstack will call DOMCTL_domaindestroy. And I got the below stack trace. >> >> It can be reproduced on Xen 4.5 (and I also suspect Xen 4.4) by returning >> in an error in vcpu_initialize. >> >> I'm not sure how to correctly fix it. > > I think a simple check at the head of the function would be ok. > > Alternatively perhaps in sched_mode_domain, which could either detect > this or could detect a domain in pool0 being moved to pool0 and short > circuit. I was thinking about the small fix below. If it's fine for everyone, I can send a patch next week. diff --git a/xen/common/schedule.c b/xen/common/schedule.c index e9eb0bc..c44d047 100644 --- a/xen/common/schedule.c +++ b/xen/common/schedule.c @@ -311,7 +311,7 @@ int sched_move_domain(struct domain *d, struct cpupool *c) } /* Do we have vcpus already? If not, no need to update node-affinity */ - if ( d->vcpu ) + if ( d->vcpu && d->vcpu[0] != NULL ) domain_update_node_affinity(d); domain_unpause(d); Regards, -- Julien Grall