[Xen-changelog] [xen-unstable] x86: Fix circular page reference destruction in relinquish_memory().

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

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1225193120 0
# Node ID 19549b9766fdd68380ded8efd975c41269ab2801
# Parent  2c20d026bb55722247c0d9ab81c125118a10346f
x86: Fix circular page reference destruction in relinquish_memory().

Tested by Jan Beulich and fixes a memory leak, but there is more to be
done here.

Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
 xen/arch/x86/domain.c |    1 -
 xen/arch/x86/mm.c     |   12 +++++++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff -r 2c20d026bb55 -r 19549b9766fd xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c     Tue Oct 28 10:37:30 2008 +0000
+++ b/xen/arch/x86/domain.c     Tue Oct 28 11:25:20 2008 +0000
@@ -1687,7 +1687,6 @@ static int relinquish_memory(
             {
                 if ( free_page_type(page, x, 0) != 0 )
                     BUG();
-                put_page(page);
                 break;
             }
         }
diff -r 2c20d026bb55 -r 19549b9766fd xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c Tue Oct 28 10:37:30 2008 +0000
+++ b/xen/arch/x86/mm.c Tue Oct 28 11:25:20 2008 +0000
@@ -1973,6 +1973,7 @@ int free_page_type(struct page_info *pag
         page->nr_validated_ptes = 1U << PAGETABLE_ORDER;
         page->partial_pte = 0;
     }
+
     switch ( type & PGT_type_mask )
     {
     case PGT_l1_page_table:
@@ -1998,6 +1999,15 @@ int free_page_type(struct page_info *pag
         BUG();
     }
 
+    return rc;
+}
+
+
+static int __put_final_page_type(
+    struct page_info *page, unsigned long type, int preemptible)
+{
+    int rc = free_page_type(page, type, preemptible);
+
     /* No need for atomic update of type_info here: noone else updates it. */
     if ( rc == 0 )
     {
@@ -2062,7 +2072,7 @@ static int __put_page_type(struct page_i
                                            x, nx)) != x) )
                     continue;
                 /* We cleared the 'valid bit' so we do the clean up. */
-                return free_page_type(page, x, preemptible);
+                return __put_final_page_type(page, x, preemptible);
             }
 
             /*

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