Re: [Xen-devel] preparing for 4.2.2 and 4.1.5

[Alex Bligh <alex@xxxxxxxxxxx>]

Jan,

--On 28 February 2013 07:31:32 +0000 Jan Beulich <JBeulich@xxxxxxxx> wrote:

> > > > On 27.02.13 at 19:44, Alex Bligh <alex@xxxxxxxxxxx> wrote:
> > --On 27 February 2013 16:12:57 +0000 Jan Beulich <JBeulich@xxxxxxxx>
> > wrote:
> > > Aiming at a release towards the end of March, I'd like to cut RC1-s
> > > at the beginning of next week.
> > I'd ask for the 'don't use O_DIRECT change'. I realise I owe the list
> > a blktrace.
> To me, the title you mention means nothing. It being on the tools
> side, it would be Ian anyway to take care of this, but can't you be
> a bit more specific and indicate which changeset/commit you're
> talking of? As well as reasoning why it would be needed (or at
> least desirable) to have on either or both trees?
See this message and the surrounding thread:
 http://markmail.org/message/iy32akdzmbjo7uiz

In essence any domU PV disk usage backended onto something that uses TCP
(e.g. iSCSI, NFS) in dom0 has the potential to crash dom0. We can replicate
this 100%. The root cause is a very-hard-to-fix skb refcount problem
in the kernel, but the obvious fix is to disable O_DIRECT in qemu's
xendisk driver. People seemed generally happy with this provided the
barriers get through (which I need to demonstrate).

--
Alex Bligh

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