Re: [Xen-devel] xm pause causing lockup

[Kip Macy <kip.macy@xxxxxxxxx>]

I think there may be a bug in your page pinning validation logic - the
lockup occurs when stepping through xen_pgd_pin. I don't know if I'm
really passing in 0, as register locals can quickly get overwritten,
but it is certainly worth checking.

Breakpoint 15, pmap_pinit (pmap=0xc06900c0) at
../../../i386-xen/i386-xen/pmap.c:1206
1206                    xen_pgd_pin(ma);
(gdb) 
Continuing.

Breakpoint 8, xen_pgd_pin (ma=0x0) at
../../../i386-xen/i386-xen/xen_machdep.c:490
490         op.cmd = MMUEXT_PIN_L2_TABLE;
(gdb) s
491         op.mfn = ma >> PAGE_SHIFT;
(gdb) 
492         xen_flush_queue();
(gdb) 

Breakpoint 4, xen_flush_queue () at ../../../i386-xen/i386-xen/xen_machdep.c:431
431         if (XPQ_IDX != 0) _xen_flush_queue();
(gdb) 
432     }
(gdb) 
xen_pgd_pin (ma=0x630f) at hypervisor.h:72
72      {
(gdb) 
76          __asm__ __volatile__ (
(gdb) 


On 4/14/05, Kip Macy <kip.macy@xxxxxxxxx> wrote:
> I haven't tracked down the problem yet, but I thought the following
> was sufficiently interesting to post:
> 
> kmacy@curly while (1)
> while? xm list
> while? sleep 5
> while? end
> Name              Id  Mem(MB)  CPU  State  Time(s)  Console
> Domain-0           0      507    0  r----     67.9
> xen-vm2            1      128    1  r----      4.0    9601
> Name              Id  Mem(MB)  CPU  State  Time(s)  Console
> Domain-0           0      507    0  r----     68.1
> xen-vm2            1      128    1  r----      4.0    9601
> Name              Id  Mem(MB)  CPU  State  Time(s)  Console
> Domain-0           0      507    0  r----     68.3
> xen-vm2            1      128    1  r----      4.0    9601
> Name              Id  Mem(MB)  CPU  State  Time(s)  Console
> Domain-0           0      507    0  r----     68.5
> xen-vm2            1      128    1  r----      4.0    9601
> Name              Id  Mem(MB)  CPU  State  Time(s)  Console
> Domain-0           0      507    0  r----     68.7
> xen-vm2            1      128    1  r----      4.0    9601
> Name              Id  Mem(MB)  CPU  State  Time(s)  Console
> Domain-0           0      507    0  r----     68.9
> xen-vm2            1      128    1  r----      4.0    9601
> 
> xen-vm2 is always shown as running, but its time is not increasing.
> 
>                -Kip
> 
> 
> On 4/13/05, Kip Macy <kip.macy@xxxxxxxxx> wrote:
> > On 4/13/05, Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> wrote:
> > > Probably easiest way to trace this is with printk's in Xen. The guts of
> > > the work is done by domain_pause_by_systemcontroller() in xen/sched.h.
> > > This in turn calls domain_sleep() in common/schedule.c.
> >
> > I traced through that code a while back when trying to decide what to
> > call from the int3 handler.
> >
> > A particularly
> > > interesting place to look will be teh synchronous spin loop at the end
> > > of domain_sleep -- if the paused domain isn't descheduled for some
> > > weird reason then the spin loop would never exit and domain0 would
> > > hang.
> >
> > Good point. It will be interesting to see.
> >
> > I sometimes wonder if I should keep some of the buggy versions of
> > FreeBSD around for regression testing as they trigger some interesting
> > behaviours in xen and xend.
> >
> >            -Kip
> >
>

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