This is a note to let you know that I've just added the patch titled
xen/balloon: set ballooned out pages as invalid in p2m
to the 3.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xen-balloon-set-ballooned-out-pages-as-invalid-in-p2m.patch
and it can be found in the queue-3.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fb9a0c443691ceaab3daba966bbbd9f5ff3aa26f Mon Sep 17 00:00:00 2001
From: David Vrabel <david.vrabel@xxxxxxxxxx>
Date: Fri, 27 Jun 2014 10:42:03 +0100
Subject: xen/balloon: set ballooned out pages as invalid in p2m
From: David Vrabel <david.vrabel@xxxxxxxxxx>
commit fb9a0c443691ceaab3daba966bbbd9f5ff3aa26f upstream.
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@xxxxxxxxxx>
Reported-by: Marek Marczykowski <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Tested-by: Marek Marczykowski <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/xen/balloon.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -426,20 +426,18 @@ static enum bp_state decrease_reservatio
* 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),
pfn_pte(page_to_pfn(scratch_page),
PAGE_KERNEL_RO), 0);
BUG_ON(ret);
- }
- 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);
}
#endif
Patches currently in stable-queue which might be from david.vrabel@xxxxxxxxxx are
queue-3.15/xen-manage-fix-potential-deadlock-when-resuming-the-console.patch
queue-3.15/xen-balloon-set-ballooned-out-pages-as-invalid-in-p2m.patch
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