From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: [PATCH 2/4] x86/PoD: Identify when a domain has already been killed from PoD exhaustion Date: Mon, 2 Nov 2015 14:07:37 +0000 Message-ID: <56376E29.3010605@citrix.com> References: <1446230022-8349-1-git-send-email-andrew.cooper3@citrix.com> <1446230022-8349-3-git-send-email-andrew.cooper3@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1446230022-8349-3-git-send-email-andrew.cooper3@citrix.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: Andrew Cooper , Xen-devel Cc: George Dunlap , Jan Beulich List-Id: xen-devel@lists.xenproject.org On 30/10/15 18:33, Andrew Cooper wrote: > p2m_pod_demand_populate() can be entered repeatedly during a single path > through the hypervisor, e.g. on a toolstack batch map operation. > > The domain might be crashed, but the interface currently lacks a way of > passing an error back through the generic p2m layer. > > Longterm the p2m layer needs reworking to allow errors to be returned, but in > the short term, avoid repeatedly re-sweeping the domain after it has already > been crashed from PoD exhaustion. > > Signed-off-by: Andrew Cooper > --- > CC: Jan Beulich > CC: George Dunlap > --- > xen/arch/x86/mm/p2m-pod.c | 3 ++- > xen/include/asm-x86/p2m.h | 2 ++ > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c > index be15cf3..6fb054f 100644 > --- a/xen/arch/x86/mm/p2m-pod.c > +++ b/xen/arch/x86/mm/p2m-pod.c > @@ -1048,7 +1048,7 @@ p2m_pod_demand_populate(struct p2m_domain *p2m, unsigned long gfn, > /* This check is done with the pod lock held. This will make sure that > * even if d->is_dying changes under our feet, p2m_pod_empty_cache() > * won't start until we're done. */ > - if ( unlikely(d->is_dying) ) > + if ( unlikely(d->is_dying) || p2m->pod.dead ) So after getting lost in a maze of twisty passages, it looks like "d->is_dying" might be the wrong thing to check here. d->is_dying is *only* set, AFAICT, in two places: - in domain_kill(), which is only called for XEN_DOMCTL_destroydomain - in domain_create(), if the creation failed for some reason. Would it make more sense to check d->is_shutting_down instead? Having some sort of pod-specific flag seems like the wrong solution. -George