David Hildenbrand 0266def913 xen/balloon: Fix mapping PG_offline pages to user space
The XEN balloon driver - in contrast to other balloon drivers - allows
to map some inflated pages to user space. Such pages are allocated via
alloc_xenballooned_pages() and freed via free_xenballooned_pages().
The pfn space of these allocated pages is used to map other things
by the hypervisor using hypercalls.

Pages marked with PG_offline must never be mapped to user space (as
this page type uses the mapcount field of struct pages).

So what we can do is, clear/set PG_offline when allocating/freeing an
inflated pages. This way, most inflated pages can be excluded by
dumping tools and the "reused for other purpose" balloon pages are
correctly not marked as PG_offline.

Fixes: 77c4adf6a6df (xen/balloon: mark inflated pages PG_offline)
Reported-by: Julien Grall <julien.grall@arm.com>
Tested-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
2019-03-15 15:35:35 +01:00
..
2018-11-10 08:58:48 -06:00