[Xen-changelog] [xen-unstable] x86/mm: Fix balooning+sharing

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
# Date 1328185651 0
# Node ID e2e2df4224e221ff7bbb9a75083d3b21f70a47d2
# Parent  23fe4a60190f11efc750af51f55228183f7bb736
x86/mm: Fix balooning+sharing

Never mind that ballooning a shared page makes no sense. We still fix it
because it may be exercised.

Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>
Signed-off-by: Tim Deegan <tim@xxxxxxx>
Committed-by: Tim Deegan <tim@xxxxxxx>
---


diff -r 23fe4a60190f -r e2e2df4224e2 xen/common/memory.c
--- a/xen/common/memory.c       Thu Feb 02 12:23:18 2012 +0000
+++ b/xen/common/memory.c       Thu Feb 02 12:27:31 2012 +0000
@@ -183,14 +183,14 @@
             
     page = mfn_to_page(mfn);
 #ifdef CONFIG_X86
-    /* If gmfn is shared, just drop the guest reference (which may or may not
-     * free the page) */
-    if(p2m_is_shared(p2mt))
+    if ( p2m_is_shared(p2mt) )
     {
-        put_page_and_type(page);
-        guest_physmap_remove_page(d, gmfn, mfn, 0);
-        put_gfn(d, gmfn);
-        return 1;
+        /* Unshare the page, bail out on error. We unshare because 
+         * we might be the only one using this shared page, and we
+         * need to trigger proper cleanup. Once done, this is 
+         * like any other page. */
+        if ( mem_sharing_unshare_page(d, gmfn, 0) )
+            return 0;
     }
 
 #endif /* CONFIG_X86 */

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