On 5/12/07 17:48, "Derek Murray" <Derek.Murray@xxxxxxxxxxxx> wrote: > Keir Fraser wrote: >> Need to bite the bullet and fix this properly by setting a software flag in >> ptes that are not subject to reference counting. > > Could we get away with testing the VM_FOREIGN flag in vm_normal_page()? > Although I get the impression that this wouldn't be easily justified if > trying to merge with upstream Linux.... Yes, this would work okay I suspect. Good enough as a stop-gap measure? Are there any other responsibilities that you acquire if you make use of VM_FOREIGN (in particular, how would this affect get_user_pages)? > Alternatively, could we use the _PAGE_GNTTAB PTE flag that is used for > debugging? Indeed, if we did this, could be obviate the need for the > PTE-zapping hook, by instead catching the case where this flag is set, > and unmapping the grant implicitly? Well, in the general case you don't have enough info to know which grant to release (a single page can be granted multiple times). > Otherwise, what would the semantics of this new flag be? It would cause pte_pfn() to return max_mapnr. It would be set for any foreign page mapping, and replace mfn_to_local_pfn() in pte_pfn(). -- Keir _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
