Re: [Xen-devel] live migration fails (assert in shadow_hash_delete)

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 23/02/2010 10:59, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote:

> Localhost migrations were just added to the automated tests. But I think
> maybe they are trivially failing due to trying to do them via the 'xl'
> interface, which doesn't support it(!). Ian?
> 
> In short, there's probably been little or no testing of live migration in
> the recent past, as I don't think Intel tests it either.

A quick manual test indicates it's very easy to get Xen to blow up. I got
the following on my first localhost live migration attempt, which is a
different looking crash in the shadow code. This is with 2.6.18 dom0 and
domU by the way, so it's not pv_ops tickling the hypervisor in an unexpected
way...

(XEN) sh error: sh_page_fault__guest_4(): Recursive shadow fault: lock was
taken by sh_page_fault__guest_4
(XEN) ----[ Xen-4.0.0-rc4  x86_64  debug=y  Not tainted ]----
(XEN) CPU:    3
(XEN) RIP:    e008:[<ffff82c4801c7984>] shadow_hash_lookup+0x11f/0x268
(XEN) RFLAGS: 0000000000010206   CONTEXT: hypervisor
(XEN) rax: 00000000c0000000   rbx: 0000000000085111   rcx: 0000000000000000
(XEN) rdx: 000000007339c000   rsi: 0000000000000000   rdi: ffff82f600000000
(XEN) rbp: ffff8300bfcdfc88   rsp: ffff8300bfcdfc18   r8:  ffffffffffffffff
(XEN) r9:  0000000000000000   r10: 0000000000000000   r11: 0000000000000001
(XEN) r12: 0000000000000008   r13: ffff8300bfce0000   r14: 0000000000000000
(XEN) r15: 00000000c0000000   cr0: 000000008005003b   cr4: 00000000000026f4
(XEN) cr3: 0000000082b46000   cr2: 00000000c0000010
(XEN) ds: 0000   es: 0000   fs: 0000   gs: 0000   ss: 0000   cs: e008
(XEN) Xen stack trace from rsp=ffff8300bfcdfc18:
(XEN)    ffff8300bc42e000 ffff8300bfce0000 ffff8300bfcdfc88 ffff82c4801e56dd
(XEN)    ffff8300bfcdfc88 0000000000000000 0000000082b44067 0000000000085111
(XEN)    ffff8300bfcdff28 ffff8300bfce0000 ffff8300bfcdff28 ffff8300bc42e000
(XEN)    0000000000082b45 0000000000000001 ffff8300bfcdfed8 ffff82c4801e7d7a
(XEN)    ffff82c48016ae3e 0000000000000260 00000000000001f0 0000000000000d20
(XEN)    0000000000083037 ffff8300bfce0218 ffff8300bfcdff28 ffff8300bfcdff28
(XEN)    0000000000083037 ffff8300bfcdff28 ffff8300bfcdff28 0000000000083037
(XEN)    00000000000000d8 ffff82c480265ce0 ffff8300bfcdff28 00000002ae907c4c
(XEN)    00000000bc42e000 ffff81c0e0655d20 ffff8300bfce0e28 0000000000082b44
(XEN)    ffff81c0caba41f0 0000000000083037 00002ae907c4c0ff 00000002bfce0000
(XEN)    0000000082b44067 ffff8300bfcdfd78 ffff82c48011e433 ffff8300bc42e000
(XEN)    ffff8300bfcdfe18 00000001801ca140 ffff8300bfcdfdb8 ffff8300bfcdfde0
(XEN)    ffff8300bfcdff28 ffff8300bfcdff28 ffff8300bfcdff28 ffff8300bfcdff28
(XEN)    ffff8300bfcdfe18 00000001801e021e ffff8300bfcdfe18 0000000100000100
(XEN)    ffffffff8020d84d ffff8300bc42e000 ffff8300bfce0000 ffff8300bc42e000
(XEN)    ffff8300bc42fa38 0000000000082b67 0000000000000001 ffff82f601056ce0
(XEN)    ffff8300bfcdfe68 ffff82c4801e9ae5 ffff8300bfce0000 ffff82f600000001
(XEN)    ffff8300bfcdff08 ffff8300bc42e000 ffff8300bc42e000 0000000000583440
(XEN)    00002ae907c4c0ff 0000000084a81067 0000000084cfa067 0000000085111067
(XEN)    0000000083037125 000000000008550a 0000000000084a81 0000000000084cfa
(XEN) Xen call trace:
(XEN)    [<ffff82c4801c7984>] shadow_hash_lookup+0x11f/0x268
(XEN)    [<ffff82c4801e7d7a>] sh_page_fault__guest_4+0xf4f/0x1fee
(XEN)    [<ffff82c48017735e>] do_page_fault+0x3b2/0x4f0
(XEN)    
(XEN) Pagetable walk from 00000000c0000010:
(XEN)  L4[0x000] = 0000000000000000 ffffffffffffffff
(XEN) 
(XEN) ****************************************
(XEN) Panic on CPU 3:
(XEN) FATAL PAGE FAULT
(XEN) [error_code=0000]
(XEN) Faulting linear address: 00000000c0000010
(XEN) ****************************************



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