Re: [Xen-devel] 3.1/2 live migration panic

[John Levon <levon@xxxxxxxxxxxxxxxxx>]

On Fri, Jan 18, 2008 at 09:41:05AM +0000, Tim Deegan wrote:

> At 22:25 +0000 on 17 Jan (1200608703), John Levon wrote:
> > (XEN) Xen call trace:
> > (XEN)    [<ffff828c801b26ba>] shadow_set_l1e+0x4f/0x14c
> > (XEN)    [<ffff828c801b5efe>] sh_page_fault__shadow_4_guest_4+0x6fe/0xb9e
> > (XEN)    [<ffff828c8016234f>] paging_fault+0x3c/0x3e
> > (XEN)    [<ffff828c801622f9>] fixup_page_fault+0x22b/0x245
> > (XEN)    [<ffff828c80162391>] do_page_fault+0x40/0x15c
> > (XEN)    
> > (XEN) Pagetable walk from ffff81ff80d64ff0:
> > (XEN)  L4[0x103] = 00000001cb03f063 000000000000063b
> > (XEN)  L3[0x1fe] = 00000001d358e067 00000000000005d4
> > (XEN)  L2[0x006] = 0000000000000000 ffffffffffffffff 
> 
> Hmmm.  This is the same error, one function further down the chain,
> which tells us something interesting.  In this case, the shadow l3e has
> been written into the l3 linear map and then used successfully via the
> l2 linear map to write the l2e, but is now missing when we come to the
> l1 linear map.  Bizarre.
> 
> Either something has changed the sl4e or sl3e under our feet (surely not
> - we have the shadow lock), or it could still be a missing TLB flush.
> If we changed the sl4e (from one present entry to another) but didn't
> flush the TLB it could cause this.

Here's another one. This time, I was running with SHADOW_OPTIMIZATIONS
== 0.

(XEN) Xen call trace:
(XEN)    [<ffff828c8018809b>] shadow_set_l2e+0x41/0x40c
(XEN)    [<ffff828c80189520>] shadow_get_and_create_l1e+0x2b3/0x344
(XEN)    [<ffff828c8018b610>] sh_page_fault__shadow_4_guest_4+0x5a7/0xba3
(XEN)    [<ffff828c8014aad0>] fixup_page_fault+0x1e0/0x1f2
(XEN)    [<ffff828c8014ab8a>] do_page_fault+0xa8/0x186
(XEN)    
(XEN) Pagetable walk from ffff81c0ffc09348:
(XEN)  L4[0x103] = 00000001ca552063 00000000000004b9
(XEN)  L3[0x103] = 00000001ca552063 00000000000004b9
(XEN)  L2[0x1fe] = 00000001ca1e2067 00000000000007cd 

regards
john

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