Re: [Xen-devel] Regression: qemu crash of hvm domUs with spice (backtrace included) - patch backport propose

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 16 Oct 2015, Fabio Fantoni wrote:
> Il 09/10/2015 09:56, Fabio Fantoni ha scritto:
> > Il 08/10/2015 17:58, Andreas Kinzler ha scritto:
> > > Is this still current? I made an interesting observation:
> > > 
> > > I had no problems with SPICE and vanilla Xen 4.5.1 when using it on Gentoo
> > > with glibc 2.19/gcc 4.6.4.
> > > Segfaults started when I switched to glibc 2.20/gcc 4.9.3 - I did not
> > > change Xen source code at all.
> > > All this might be related to:
> > > https://lists.nongnu.org/archive/html/qemu-devel/2015-06/msg02764.html
> > > 
> > > Andreas
> > 
> > Thanks for your mail.
> > The problem I had seems different, I not found the exactly cause but I
> > solved using newer qemu (2.2 from unstable - now 4.6) with xen 4.5.1.
> > Big distro I saw already use newer qemu and should be ok.
> > I still using glibc < 2.20 in my debian servers, this is probably because I
> > not had your problem but I think that backport the patch you linked can be
> > useful for solve a qemu crash case, I'll test it in my next build and if
> > I'll not found regression I'll require the backport for xen qemu gits.
> > 
> > > 
> > > > https://github.com/Fantu/Xen/commits/rebase/m2r-staging
> > > > Latest test with regression based on latest stable-4.5, more exactly:
> > > > https://github.com/Fantu/Xen/commits/rebase/m2r-testing
> > > > Some days ago on same dom0 and domU I tried with latest stable version
> > > > (that I use on only 2 production servers for now but I not saw the
> > > > regression), more exactly:
> > > > https://github.com/Fantu/Xen/commits/rebase/m2r-stable-4.5
> > > > Dom0 debian 7 with kernel 3.16 from backports, seabios 1.8.1-2 from
> > > > unstable and this xen configure:
> > > > ./configure --prefix=/usr --disable-blktap1 --disable-qemu-traditional
> > > > --disable-rombios --with-system-seabios=/usr/share/seabios/bios-256k.bin
> > > > --with-extra-qemuu-configure-args="--enable-spice --enable-usb-redir"
> > > > --disable-blktap2
> > > > 
> > > > I suppose that there is unexpected case caused by a backports or missed
> > > > patch/es to backports from unstable.
> > > > I not found with a fast look rilevant patch to try to revert, can anyone
> > > > suggest me the more probable point/s for bisect and/or patch to revert
> > > > or I must try full bisect 4.5.0->stable-4.5?
> > > > 
> > > 
> > 
> 
> I tried to use xen 4.6 with its qemu plus cherry-pick of this patch:
> http://git.qemu.org/?p=qemu.git;a=commit;h=c6e484707f28b3e115e64122a0570f6b3c585489
> - spice-display: fix segfault in qemu_spice_create_update
> Used some days without see regression.
> Probably is useful apply it to qemu-xen unstable and 4.6 (about older versions
> I don't know and I not tested).
> @Stefano Stabellini: can you take a look to it please?

It looks like a reasonable effort.  My test machines are unavailable at
the moment, when they are back I'll commit (assuming it passes the
tests).


> About qemu used in unstable I think is good update to 2.4.0.1 now that xen 4.7
> devel is started, I think we keep upstream qemu updated with too many latency
> and there is a more high bug risk with xen for major of distro that use newer
> qemu version (following stable version of both).

I'll upgrade QEMU as soon as possible.

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