RE: [Xen-devel] Live migration fails under heavy network use

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> I've observed this with both a Solaris and a FC6 domU (up to date as
of
> bash-3.00# while xm migrate --live fedora64 localhost ; do echo done ;
done
> (XEN) memory.c:188:d2 Dom2 freeing in-use page 9f40f (pseudophys
1d007):
> count=2 type=e8000000
> (XEN) memory.c:188:d2 Dom2 freeing in-use page 9f409 (pseudophys
1d00b):
> count=2 type=e8000000
> (XEN) /export/johnlev/xen/xen-work/xen.hg/xen/include/asm/mm.h:184:d0
Error
> pfn 9f738: rd=ffff830000fe0100, od=ffff830000000002, caf=00000000,
> taf=0000000000000002
> (XEN) mm.c:590:d0 Error getting mfn 9f738 (pfn 12026) from L1 entry
> 000000009f738705 for dom2
> Error: /usr/lib/xen/bin/xc_save 27 2 0 0 1 failed
> 
> Some experimentation has revealed that this only happens if a vif is
> configured
> and used, which seems like it's related to giving away pages (as rd !=
od
> would
> indicate too...). Anybody else seeing this? I've only tested on a
Solaris
> dom0
> so far, though I can't think of anything that would affect this.

These guests are using rx-flip rather than rx-copy, right?
This has certainly worked reliably in the past (e.g. 3.0.3), but is now
getting little testing as current guests use rx-copy by default.

The freeing in-use page messages may be unrelated to the actual problem
-- AFAIK that's a relatively new printk that could occur benignly during
a live migrate of an rx-flip guest.

Even get_page can fail benignly under certain circumstances during a
live migrate. It's worth finding out where the actual error in
xc_linux_save is.

Ian
 



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