From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: null domains | xen4.4 Date: Mon, 1 Dec 2014 09:59:18 +0000 Message-ID: <1417427958.27655.1.camel@citrix.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Alexey Cc: Xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On Mon, 2014-12-01 at 12:48 +0300, Alexey wrote: > Hi, all! > > We are once again faced with the null-domains problem. > At this moment we have xen node with 49 null-domains and if I create new > domain and shutdown it I w'll get a new one null-domain. > > All blkback and netback kernel process are exists. There is no qemu > process running. > I can't delete any vif or stop disk, which was used by dead domain. What do you mean here, does a vif or disk still exist for the dead domain then? > How we can prevent appearance of null-domains? > How we can unlock resources of existing null-domains? A null domain remains when a page owned by that domain is still referenced from somewhere. The output of the 'q' debug key sometimes exposes the source of such references. ("xl debug-key q" will send that, the result appears in "xl dmesg", alternatively Ctrl-A three times on the serial console then 'q'). > # xl info > host : xen23 > release : 3.10-3-amd64 Any chance you could try a newer dom0 kernel? > xen_commandline : tmem=1 loglvl=all noreboot dom0_mem=5120M > dom0_vcpus_pin console=vga vga=current Are you able to reproduce when tmem is not enabled? Ian.