[Xen-changelog] [xen-unstable] xen: Do not BUG_ON page count_info in free_domheap_pages().

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxxxxxxxx>
# Date 1175866483 -3600
# Node ID 6625adf359dc8c64e2da3802585fb378f4863925
# Parent  755207b3c47c6a379229c29d26e0a8d494630940
xen: Do not BUG_ON page count_info in free_domheap_pages().
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 xen/arch/x86/mm/shadow/common.c |    3 ---
 xen/common/page_alloc.c         |   14 +++++++++++++-
 2 files changed, 13 insertions(+), 4 deletions(-)

diff -r 755207b3c47c -r 6625adf359dc xen/arch/x86/mm/shadow/common.c
--- a/xen/arch/x86/mm/shadow/common.c   Fri Apr 06 11:27:36 2007 +0100
+++ b/xen/arch/x86/mm/shadow/common.c   Fri Apr 06 14:34:43 2007 +0100
@@ -1245,9 +1245,6 @@ static unsigned int sh_set_allocation(st
             list_del(&sp->list);
             d->arch.paging.shadow.free_pages -= 1<<SHADOW_MAX_ORDER;
             d->arch.paging.shadow.total_pages -= 1<<SHADOW_MAX_ORDER;
-            for ( j = 0; j < 1<<SHADOW_MAX_ORDER; j++ ) 
-                /* Keep the page allocator happy */
-                ((struct page_info *)sp)[j].count_info = 0;
             free_domheap_pages((struct page_info *)sp, SHADOW_MAX_ORDER);
         }
 
diff -r 755207b3c47c -r 6625adf359dc xen/common/page_alloc.c
--- a/xen/common/page_alloc.c   Fri Apr 06 11:27:36 2007 +0100
+++ b/xen/common/page_alloc.c   Fri Apr 06 14:34:43 2007 +0100
@@ -445,7 +445,19 @@ static void free_heap_pages(
 
     for ( i = 0; i < (1 << order); i++ )
     {
-        BUG_ON(pg[i].count_info != 0);
+        /*
+         * Cannot assume that count_info == 0, as there are some corner cases
+         * where it isn't the case and yet it isn't a bug:
+         *  1. page_get_owner() is NULL
+         *  2. page_get_owner() is a domain that was never accessible by
+         *     its domid (e.g., failed to fully construct the domain).
+         *  3. page was never addressable by the guest (e.g., it's an
+         *     auto-translate-physmap guest and the page was never included
+         *     in its pseudophysical address space).
+         * In all the above cases there can be no guest mappings of this page.
+         */
+        pg[i].count_info = 0;
+
         if ( (d = page_get_owner(&pg[i])) != NULL )
         {
             pg[i].tlbflush_timestamp = tlbflush_current_time();

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