[Xen-devel] [PATCH v2] mm: disallow MEMF_no_refcount to be passed for domain-owned allocations

["Jan Beulich" <JBeulich@xxxxxxxx>]

When such pages get assigned to domains (and hence their ->tot_pages
not incremented accordingly) we would otherwise also need to suppress
decrementing the count when freeing those pages.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Add ASSERT_UNREACHABLE().

--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -2303,6 +2303,11 @@ struct page_info *alloc_domheap_pages(
 
     if ( memflags & MEMF_no_owner )
         memflags |= MEMF_no_refcount;
+    else if ( (memflags & MEMF_no_refcount) && d )
+    {
+        ASSERT_UNREACHABLE();
+        return NULL;
+    }
 
     if ( dma_bitsize && ((dma_zone = bits_to_zone(dma_bitsize)) < zone_hi) )
         pg = alloc_heap_pages(dma_zone + 1, zone_hi, order, memflags, d);



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