[NTOS:Mm] Handle RosMm pages in MiDecrementReferenceCount

This is required, when RosMm unmaps locked pages and they later get unlocked.

ntoskrnl/mm/ARM3/pfnlist.c

@@ -1219,6 +1219,10 @@ MiDecrementShareCount(IN PMMPFN Pfn1,
     }
 }
 
+VOID
+NTAPI
+MmDereferencePage(PFN_NUMBER Pfn);
+
 VOID
 NTAPI
 MiDecrementReferenceCount(IN PMMPFN Pfn1,
@@ -1227,6 +1231,13 @@ MiDecrementReferenceCount(IN PMMPFN Pfn1,
     /* PFN lock must be held */
     MI_ASSERT_PFN_LOCK_HELD();
 
+    /* Handle RosMm PFNs here, too (in case they got locked/unlocked by ARM3) */
+    if (MI_IS_ROS_PFN(Pfn1))
+    {
+        MmDereferencePage(PageFrameIndex);
+        return;
+    }
+
     /* Sanity checks on the page */
     if (PageFrameIndex > MmHighestPhysicalPage ||
         Pfn1 != MI_PFN_ELEMENT(PageFrameIndex) ||