[Xen-devel] Re: tmem and preemption in xen-unstable

[Keir Fraser <keir.xen@xxxxxxxxx>]

No, it's just extra debug checking that I left disabled in 4.1 release. It
means someone did something like an rcu lock without matching unlock, or
similar. Harmless until someone actually uses the preemption stuff, but
should be fixed.

 -- Keir


On 08/07/2011 20:50, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> Hi Keir --
> 
> I haven't been able to try xen-unstable for awhile and don't
> have a free machine right now to reproduce this, but someone
> trying tmem on xen-unstable ran into the following crash,
> which is not reproducible on Xen 4.1.1.  I wonder if it
> might be related to the recent preemption support you added.
> 
> I'll get more info when I can but thought I'd pass this
> on now in case you have an obvious solution (like maybe
> there's a boot option to disable preemptibility?).
> 
> Thanks,
> Dan
> 
>> With a serial console I was able to capture this. Let me rebuild it with
>> Xen 4.1.1:
>> 
>> [ 6401.044014] switch: port 2(vif7.0) entering forwarding state
>> [ 6401.044014] switch: port 2(vif7.0) entering forwarding state
>> (XEN) tmem: allocating ephemeral-private tmem pool for
>> domid=7...pool_id=1
>> [ 6411.298189] vif7.0: no IPv6 routers present
>> [ 6416.096101] switch: port 2(vif7.0) entering forwarding state
>> (XEN) Assertion '!in_atomic()' failed at softirq.c:61
>> (XEN) ----[ Xen-4.2-110707  x86_64  debug=y  Tainted:    C ]----
>> (XEN) CPU:    0
>> (XEN) RIP:    e008:[<ffff82c480122e85>] do_softirq+0xd/0x28
>> (XEN) RFLAGS: 0000000000010202   CONTEXT: hypervisor
>> (XEN) rax: 0000000000000001   rbx: ffff8300cfe80000   rcx:
>> ffff82c4802b0880
>> (XEN) rdx: 0000000000000000   rsi: ffff8800135dde40   rdi:
>> 0000000000000000
>> (XEN) rbp: ffff82c480297f08   rsp: ffff82c480297f08   r8:
>> 0000000000000009
>> (XEN) r9:  ffff8800135dde78   r10: ffff8800135dde40   r11:
>> 0000000000000000
>> (XEN) r12: ffff88000f3e1de0   r13: ffff880002cc03c0   r14:
>> ffff880079265f00
>> (XEN) r15: 0000000000000001   cr0: 0000000080050033   cr4:
>> 00000000000006f0
>> (XEN) cr3: 00000001b1b91000   cr2: ffff88000ecc9000
>> (XEN) ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: 0000   cs: e008
>> (XEN) Xen stack trace from rsp=ffff82c480297f08:
>> (XEN)    00007d3b7fd680c7 ffff82c480210046 0000000000000001
>> ffff880079265f00
>> (XEN)    ffff880002cc03c0 ffff88000f3e1de0 ffff88000f3e1d38
>> ffff88000f3e1e48
>> (XEN)    0000000000000000 ffff8800135dde40 ffff8800135dde78
>> 0000000000000009
>> (XEN)    ffffffff81623700 ffff8800135dde40 0000000000000000
>> ffff8800135dde40
>> (XEN)    ffff8800135dde40 000000f900000000 ffffffff8112c782
>> 000000000000e033
>> (XEN)    0000000000000202 ffff88000f3e1cc8 000000000000e02b
>> 0000000000000000
>> (XEN)    0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
>> (XEN)    ffff8300cfe80000 0000000000000000 0000000000000000
>> (XEN) Xen call trace:
>> (XEN)    [<ffff82c480122e85>] do_softirq+0xd/0x28
>> (XEN)
>> (XEN)
>> (XEN) ****************************************
>> (XEN) Panic on CPU 0:
>> (XEN) Assertion '!in_atomic()' failed at softirq.c:61
>> (XEN) ****************************************
>> (XEN)
>> (XEN) Reboot in five seconds...



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