From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: [PATCH] x86: fix improper return value from relinquish_memory() Date: Wed, 24 Mar 2010 14:54:54 +0000 Message-ID: References: <20100324144313.GB2245@phenom.dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100324144313.GB2245@phenom.dumpdata.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Konrad Rzeszutek Wilk , Jan Beulich Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On 24/03/2010 14:43, "Konrad Rzeszutek Wilk" wrote: >> Btw., the reason I was looking at that code was that we observe >> zombie domains - ones in DOMDYING_dead state, perhaps having >> almost none of their memory freed (shadowed guests appear to be >> particularly bad). In one of the reports, an interesting extra fact >> was that this happened only for the first 100 guests - any >> subsequent ones got destroyed properly (obviously to get there >> this requires quite a bit of memory in the host). Has anyone else >> observed this? Does this ring any bells? > > Yes. > http://lists.xensource.com/archives/html/xen-devel/2008-12/msg00222.html > > B/c of the page count we had guests that would never have their mmap > count removed causing them to be zombie guests. Our fix, which wasn't > nice, was to have the guest domain id re-number and shove it and its > remaining page ownership (at that point it only has some pages in Dom0 > and DomU) in a corner. There's a big difference between a zombie domain owning a few pages versus a zombie domain still having most of its memory, though. One could be a ref-count leak, the other sounds potentially like something wrong with the domain-killing routines (not that there's enough data to definitely say either way for sure yet -- but at least they do sound like different bugs). -- Keir