Re: [Xen-devel] page refcount on pages mapped by the toolstack..

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Thu, 06 Dec 2012 10:49:54 +0000
"Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
> Did you perhaps not monitor the changes to the refcnt closely
> enough? It ought to be 2 when the guest is up (on reference for
> the _PGC_allocated bit, and another for it to be mapped
> somewhere in the guest). I.e. between Dom0 creating the guest
> (and touching its memory) and the guest actually starting, there
> could be further adjustments to the refcnt that simply sum up to
> zero.

Correct, it's 2 when the guest is up. Then relinquish_memory() seems to
bring it to 0 when domain destroy is called. 

For PVH, I somehow end up with 3 when guest is up, so when guest is destroyed
the mfn's are around with refcnt of 1. I get refcnt on the page in xen
when doing xen_remap_domain_mfn_range() in dom0. I hold on to the refcnt
until xen_unmap_domain_mfn_range(). Unmap results in call to 
XENMEM_remove_from_physmap where I do put_page if it's not a grant page
and is from foreign domain....  Debugging that right now.

Thanks for the help,
Mukesh


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel