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Re: [Xen-devel] live migration can fail due to XENMEM_maximum_gpfn
| To: | John Levon <levon@xxxxxxxxxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] live migration can fail due to XENMEM_maximum_gpfn |
| From: | Isaku Yamahata <yamahata@xxxxxxxxxxxxx> |
| Date: | Tue, 7 Oct 2008 10:54:32 +0900 |
| Cc: | jeremy@xxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx |
| Delivery-date: | Mon, 06 Oct 2008 18:54:53 -0700 |
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On Mon, Oct 06, 2008 at 05:47:53PM +0100, John Levon wrote: > > There's a race that can cause live migration to fail. In particular, > xc_save uses XENMEM_maximum_gpfn to create the shm segment. qemu then > also uses that value to look up the segment. However, the value can > easily change in between due to p2m_set_entry(). In particular if > there's PV drivers in the HVM domU, ->max_mapped_pfn can change easily: > > dom 11 max gpfn 262143 > dom 11 max gpfn 262143 > dom 11 max gpfn 262143 > .... > dom 11 max gpfn 985087 > > (1Gb Solaris HVM domU). > > I'm not sure how this should be fixed? I think a similar race would exist once balloon expansion (using memory hot plug) is implemented. According to http://wiki.xensource.com/xenwiki/XenParavirtOps, it is WIP, though. -- yamahata _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel |
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