diff options
authorDavid Vrabel <david.vrabel@citrix.com>2014-06-27 10:42:03 +0100
committerDavid Vrabel <david.vrabel@citrix.com>2014-07-04 15:17:43 +0100
commitfb9a0c443691ceaab3daba966bbbd9f5ff3aa26f (patch)
parent1b6478231c6f5f844185acb32045cf195028cfce (diff)
xen/balloon: set ballooned out pages as invalid in p2m
Since cd9151e26d31048b2b5e00fd02e110e07d2200c9 (xen/balloon: set a mapping for ballooned out pages), a ballooned out page had its entry in the p2m set to the MFN of one of the scratch pages. This means that the p2m will contain many entries pointing to the same MFN. During a domain save, these many-to-one entries are not identified as such and the scratch page is saved multiple times. On restore the ballooned pages are populated with new frames and the domain may use up its allocation before all pages can be restored. Since the original fix only needed to keep a mapping for the ballooned page it is safe to set ballooned out pages as INVALID_P2M_ENTRY in the p2m (as they were before). Thus preventing them from being saved and re-populated on restore. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Reported-by: Marek Marczykowski <marmarek@invisiblethingslab.com> Tested-by: Marek Marczykowski <marmarek@invisiblethingslab.com> Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Cc: <stable@vger.kernel.org>
1 files changed, 5 insertions, 7 deletions
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index b7a506f2bb14..5c660c77f03b 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -426,20 +426,18 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
* p2m are consistent.
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
- unsigned long p;
- struct page *scratch_page = get_balloon_scratch_page();
if (!PageHighMem(page)) {
+ struct page *scratch_page = get_balloon_scratch_page();
ret = HYPERVISOR_update_va_mapping(
(unsigned long)__va(pfn << PAGE_SHIFT),
- }
- p = page_to_pfn(scratch_page);
- __set_phys_to_machine(pfn, pfn_to_mfn(p));
- put_balloon_scratch_page();
+ put_balloon_scratch_page();
+ }
+ __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);