RE: [Xen-devel] Domain 0 stop response on frequently reboot VMS

[MaoXiaoyun <tinnycloud@xxxxxxxxxxx>]

Hi Daniel:
 
     Sorry for tht late response, and really thanks for your kindly suggestion.
     Well, I believe we will upgrade to the lastest kernel in the coming future, but currently
we perfer to maintain for stable reason.
 
    Our kernel version is 2.6.31. Now I am going through the change set of blktap to get
more detail info.
 
   thanks.
 
> Subject: RE: [Xen-devel] Domain 0 stop response on frequently reboot VMS
> From: daniel.stodden@xxxxxxxxxx
> To: tinnycloud@xxxxxxxxxxx; jeremy@xxxxxxxx
> CC: keir@xxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx
> Date: Mon, 18 Oct 2010 14:17:50 -0700
>
>
> I'd strongly suggest to try upgrading your kernel, or at least the
> blktap component. The condition below is new to me, but that wait_queue
> file and some related code was known to be buggy and has long since been
> removed.
>
> If you choose to only upgrade blktap from tip, let me know what kernel
> version you're dealing with, you might need to backport some of the
> device queue macros to match your version's needs.
>
> Daniel
>
>
> On Sat, 2010-10-16 at 01:39 -0400, MaoXiaoyun wrote:
> > Well, Thanks Keir.
> > Fortunately we caught the bug, it turned out to be a tapdisk problem.
&g t; > A brief explaination for other guys might confront this issue.
> >
> > Clear BLKTAP_DEFERRED on line 19 will lead to the concurrent access
> > of
> > tap->deferred_queue between line 24 and 37, which will finally cause
> > bad
> > pointer of tap->deferred_queue, and infinte loop in while clause in
> > line 22.
> > Lock line 24 will be a simple fix.
> >
> > /linux-2.6-pvops.git/drivers/xen/blktap/wait_queue.c
> > 9 void
> > 10 blktap_run_deferred(void)
> > 11 {
> > 12 LIST_HEAD(queue);
> > 13 struct blktap *tap;
> > 14 unsigned long flags;
> > 15
> > 16 spin_lock_irqsave(&deferred_work_lock, flags);
> > 17 list_splice_init(&deferred_work_queue, &queue);
> > 18 list_for_each_entry(tap, &queue, deferred_queue)
> > 19 clear_bit(BLKTAP_DEFERRED, &tap->d ev_inuse);
> > 20 spin_unlock_irqrestore(&deferred_work_lock, flags);
> > 21
> > 22 while (!list_empty(&queue)) {
> > 23 tap = list_entry(queue.next, struct blktap,
> > deferred_queue);
> > 24 &nb sp; list_del_init(&tap->deferred_queue);
> > 25 blktap_device_restart(tap);
> > 26 }
> > 27 }
> > 28
> > 29 void
> > 30 blktap_defer(struct blktap *tap)
> > 31 {
> > 32 unsigned long flags;
> > 33
> > 34 spin_lock_irqsave(&deferred_work_lock, flags);
> > 35 if (!test_bit(BLKTAP_DEFERRED, &tap->dev_inuse)) {
> > 36 set_bit(BLKTAP_DEFERRED, &tap->dev_inuse);
> > 37 list_add_tail(&tap->deferred_queue, &deferred_work_queue);
> > 38 }
> > 39 spin_unlock_irqrestore(&deferred_work_lock, f lags);
> > 40 }
> >
> >
&g t; > > Date: Fri, 15 Oct 2010 13:57:09 +0100
> > > Subject: Re: [Xen-devel] Domain 0 stop response on frequently reboot
> > VMS
> > > From: keir@xxxxxxx
> > > To: tinnycloud@xxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx
> > >
> > > You'll probably want to see if you can get SysRq output from dom0
> > via serial
> > > line. It's likely you can if it is alive enough to respond to ping.
> > This
> > > might tell you things like what all processes are getting blocked
> > on, and
> > > thus indicate what is stopping dom0 from making progress.
> > >
> > > -- Keir
> > >
> > > On 15/10/2010 13:43, "MaoXiaoyun" <tinnycloud@xxxxxxxxxxx> wrote:
> > >
> > > >
> > > > Hi Keir:
> > > >
> > > > First, I'd like to express my appr eciation for the help your
> > offered
> > > > before.
> > > > Well, recently we confront a rather nasty domain 0 no response
> > > > problem.
> > > >
> > > > We still have 12 HVMs almost continuously and con currently reboot
> > > > test on a physical server.
> > > > A few hours later, the server looks like dead. We only can ping to
> > > > the server and get right response,
> > > > the Xen works fine since we can get debug info from serial port.
> > Attached is
> > > > the full debug output.
> > > > After decode the domain 0 CPU stack, I find the CPU still works
> > for domain 0
> > > > since the stack changed
> > > > info changed every time I dumped.
> > > >
> > > > Could help to take a look at the attentchment to see wheth er there
> > are
> > > > some hints for debugging this
> > > > problem. Thanks in advance.
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > Xen-devel mailing list
> > > > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > > > http://lists.xensource.com/xen-devel
> > >
> > >
>
>

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