From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes. Date: Mon, 11 Mar 2013 13:48:14 -0400 Message-ID: <20130311174814.GA14296@phenom.dumpdata.com> References: <5139C915.5080309@eu.citrix.com> <1362742844-6679-1-git-send-email-alex@alex.org.uk> <513DED4D.9040004@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <513DED4D.9040004@eu.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: George Dunlap Cc: Ian Campbell , Stefano Stabellini , Alex Bligh , Ian Jackson , xen-devel , Jan Beulich , Anthony Perard List-Id: xen-devel@lists.xenproject.org On Mon, Mar 11, 2013 at 02:42:21PM +0000, George Dunlap wrote: > On 11/03/13 14:02, Alex Bligh wrote: > > > >--On 8 March 2013 12:54:16 +0000 George Dunlap > > wrote: > > > >>On Fri, Mar 8, 2013 at 11:40 AM, Alex Bligh wrote: > >>>Due to what is almost certainly a kernel bug, writes with > >>>O_DIRECT may continue to reference the page after the write > >>>has been marked as completed, particularly in the case of > >>>TCP retransmit. In other scenarios, this "merely" risks > >>>data corruption on the write, but with Xen pages from domU > >>>are only transiently mapped into dom0's memory, resulting > >>>in kernel panics when they are subsequently accessed. > >>> > >>>This brings PV devices in line with emulated devices. Removing > >>>O_DIRECT is safe as barrier operations are now correctly passed > >>>through. > >>Not qualified to comment on the technical merits of the patch, but re > >>the commit message: > >> > >>Acked-by: George Dunlap > >Any further thoughts on this one? > > I believe that Stefano is the person to commit it, but he's on > holiday for two weeks. Who is his backup? > > -George