Re: [Xen-devel] {PATCH] Add p2m_lock in set_shared_p2m_entry

To:	Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Subject:	Re: [Xen-devel] {PATCH] Add p2m_lock in set_shared_p2m_entry
From:	Jui-Hao Chiang <juihaochiang@xxxxxxxxx>
Date:	Thu, 6 Jan 2011 22:52:30 +0800
Cc:	xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date:	Thu, 06 Jan 2011 06:53:19 -0800
Dkim-signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:cc:content-type; bh=6Gj+vK52zmtOMADYn5MTm456eLXrmtxe6Vsyq4O016c=; b=GMJocloebpMEMl9aR3Z9m9+ixJS0L7uoMHWdBNNhGoR4+1QlnFyrtrqfOs8cmmmBcD GWU//16EAsKnCtheZxqdBGtcaPgsNQaTBGYJpjEm/98NbDyUMPnHs3DQhpgpSgotMd7P eAQ/ZFP6WDIaIa41/T1h4IpUgNdW0jPhccYUs=
Domainkey-signature:	a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=kg4oY/qKMNuQO6mfdiy3bmQPPG0URsJktc+v0rBNCHgY1Em7uyM69mAnw5YjkOGQdU 8NAd+DpFyZx+FvLUQMFiNyNfsTi+NnJm9Wb7qvhEU9M2vT9CunSXf9bQHUHUs9YR3vX4 OE4DLLB91ziE+o7lfTqhNfc81+TXagBNBHGfc=
Envelope-to:	www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to:	<20110104112340.GB21948@xxxxxxxxxxxxxxxxxxxxxxx>
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>
References:	<AANLkTi=MXPP2d7kai-gjxCPbJoJcwpU0VVzTO+DjCrsT@xxxxxxxxxxxxxx> <20110104112340.GB21948@xxxxxxxxxxxxxxxxxxxxxxx>
Sender:	xen-devel-bounces@xxxxxxxxxxxxxxxxxxx

Hi, Tim

Thanks. I'll have to make a slightly more complex fix, as
set_shared_p2m_entry() can be called (via p2m_teardown() and
mem_sharing_unshare_page()) with the p2m lock already held. :(

Actually our original problem is the mem_sharing_share_pages() doesn't hold the p2m lock when calling set_shared_p2m_entry(), which causes the share operation to die.

That's a sign of a deeper illness which will probably lead to deadlocks
elsewhere. I intend to give the MM locking (p2m, shadow, hap, log-dirty
and page-sharing locks) a good kicking some time soon, maybe after 4.1
is released.

Just saw your patch http://xenbits.xensource.com/xen-unstable.hg?rev/a8d69de8eb31.

Thanks,
Jui-Hao

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

WARNING - OLD ARCHIVES

xen-devel

Re: [Xen-devel] {PATCH] Add p2m_lock in set_shared_p2m_entry