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

[Fabio Fantoni <fabio.fantoni@xxxxxxx>]

Il 11/05/2015 17:04, Fabio Fantoni ha scritto:
> Il 21/04/2015 14:53, Stefano Stabellini ha scritto:
> > On Tue, 21 Apr 2015, Fabio Fantoni wrote:
> > > Il 21/04/2015 12:49, Stefano Stabellini ha scritto:
> > > > On Mon, 20 Apr 2015, Fabio Fantoni wrote:
> > > > > I updated xen and qemu from xen 4.5.0 with its upstream qemu 
> > > > > included to
> > > > > xen
> > > > > 4.5.1-pre with qemu upstream from stable-4.5 (changed Config.mk to 
> > > > > use
> > > > > revision "master").
> > > > > After few minutes I booted windows 7 64 bit domU qemu crash, tried 
> > > > > 2 times
> > > > > with same result.
> > > > >
> > > > > In the domU's qemu log:
> > > > > > qemu-system-i386: malloc.c:3096: sYSMALLOc: Assertion `(old_top ==
> > > > > > (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) -
> > > > > > __builtin_offsetof
> > > > > > (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long)
> > > > > > (old_size) >= (unsigned long)((((__builtin_offsetof (struct
> > > > > > malloc_chunk,
> > > > > > fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * 
> > > > > > (sizeof(size_t))) -
> > > > > > 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & 
> > > > > > pagemask)
> > > > > > ==
> > > > > > 0)' failed.
> > > > > > Killing all inferiors
> > > > > In attachment the full backtrace of qemu crash.
> > > > >
> > > > > With a fast search after I saw the backtrace I found a probable 
> > > > > cause of
> > > > > regression (I'm not sure):
> > > > > http://xenbits.xen.org/gitweb/?p=staging/qemu-upstream-4.5-testing.git;a=commit;h=5c3402816aaddb15156c69df73c54abe4e1c76aa 
> > > > >
> > > > > spice: make sure we don't overflow ssd->buf
> > > > >
> > > > > Added also qemu-devel and spice-devel as cc.
> > > > >
> > > > > If you need more informations/tests tell me and I'll post them.
> > > >    Maybe you could try to revert the offending commit
> > > > (5c3402816aaddb15156c69df73c54abe4e1c76aa)? Or even better bisect the
> > > > crash?
> > > Thanks for your reply.
> > >
> > > I reverted to 4.5.0 on dom0 for now on that system because I'm busy 
> > > trying to
> > > found another problem that cause very bad performance without errors or
> > > nothing in logs :( I don't know if if xen related, kernel related or 
> > > other for
> > > now.
> > >
> > > About this regression with spice I'll do further tests in next days 
> > > (probably
> > > starting reverting the spice patch in qemu) but any help is 
> > > appreciated.
> > > Based on data I have for now is possible that the problem is that 
> > > qemu try to
> > > allocate other ram or videoram after domU create but with xen is not 
> > > possible?
> > > In the spice related patch I saw something about dynamic allocation for
> > > example.
> > It is probably caused by a commit in the range:
> >
> > 1ebb75b1fee779621b63e84fefa7b07354c43a99..0b8fb1ec3d666d1eb8bbff56c76c5e6daa2789e4 
> >
> > there are only 10 commits in that range. By using git bisect you should
> > be able to narrow it down in just 3 tests.
> Sorry for delay, I was busy with many things, today I retried with 
> updated stable-4.5 and also reverting "spice: make sure we don't 
> overflow ssd->buf" (in a second test) but in both case regression 
> remain :(
> Tomorrow probably I'll do other tests.
I did another test, reverting this instead:
http://xenbits.xen.org/gitweb/?p=qemu-upstream-4.5-testing.git;a=commit;h=c9ac5f816bf3a8b56f836b078711dcef6e5c90b8
And now seems I'm unable to reproduce the regression, before happen 
after few seconds up to 1-2 minutes, now I use the same domU 15-20 
minutes without problem.
Probably is the cause of regression even if seems strange that on 
unstable with same patch on tests of some days ago didn't happen.
Any ideas?

Thanks for any reply and sorry for my bad english.

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