This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] doubt on releasing domain pages

To: Sandesh <sandesh.ahiremath@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] doubt on releasing domain pages
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Fri, 22 Aug 2008 08:18:07 +0100
Delivery-date: Fri, 22 Aug 2008 00:18:27 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <1219354128.4327.16.camel@ec4t16cg-1518809>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AckEJzlmeAfmeHAaEd2ywQAWy6hiGQ==
Thread-topic: [Xen-devel] doubt on releasing domain pages
User-agent: Microsoft-Entourage/
On 21/8/08 22:28, "Sandesh" <sandesh.ahiremath@xxxxxxxxx> wrote:

>   I am trying to release domU pages from page_list and xenpage_list
> after domU shutdown while retaining the rest of the domain information.
> To achieve this in __domain_finalise_shutdown i call
> domain_relinquish_resources. This is failing to release pages from
> page_list for type PGT_l2_page_tables and crashing dom0.
>   To be specific, while testing on mini-os i saw that when
> domain_relinquish_resources calls relinquish_memory for
> PGT_l2_page_tables, this eventually calls free_l2_table which fails at
> map_domain_page() by returning an invalid virtual address, due to which
> dom0 crashes immediately.
> When the same sequence of functions works perfectly fine during domU
> destruction, why not during shutdown. Am I missing anything important?

I wouldn't guarantee that calling from shutdown will work entirely race-free
in all cases, but I would think it would generally work okay. A bad pointer
from map_domain_page() is odd -- make a debug build 'debug=y make' and
perhaps add tracing to see what's going wrong there.

 -- Keir

Xen-devel mailing list

<Prev in Thread] Current Thread [Next in Thread>