Re: [Xen-devel] [PATCHv3] QEMU(upstream): Disable xen's use of O_DIRECT by default as it results in crashes.

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Stefano Stabellini writes ("Re: [PATCHv3] QEMU(upstream): Disable xen's use of 
O_DIRECT by default as it results in crashes."):
> On Fri, 8 Mar 2013, 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.
> > 
> > See:
> >   http://lists.xen.org/archives/html/xen-devel/2012-12/msg01154.html
> > for more details.
> > 
> > Signed-off-by: Alex Bligh <alex@xxxxxxxxxxx>
> 
> 
> Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

Marvellous, pushed to staging/qemu-upstream-unstable.git

Thanks,
Ian.

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