Fix potential issue with partial unmap

We must also do the unmap operation with the RWLock, otherwise faults on the unmapped region will cause crashes and the whole thing becomes pointless

Ryujinx.Memory/WindowsShared/PlaceholderManager.cs

@@ -293,18 +293,14 @@ namespace Ryujinx.Memory.WindowsShared
 
                 if (IsMapped(overlap.Value))
                 {
-                    ulong overlapStart = overlap.Start;
-                    ulong overlapEnd = overlap.End;
-                    ulong overlapValue = overlap.Value;
-
                     lock (_mappings)
                     {
                         _mappings.Remove(overlap);
-                        _mappings.Add(new RangeNode<ulong>(overlapStart, overlapEnd, ulong.MaxValue));
+                        _mappings.Add(new RangeNode<ulong>(overlap.Start, overlap.End, ulong.MaxValue));
                     }
 
-                    bool overlapStartsBefore = overlapStart < startAddress;
-                    bool overlapEndsAfter = overlapEnd > endAddress;
+                    bool overlapStartsBefore = overlap.Start < startAddress;
+                    bool overlapEndsAfter = overlap.End > endAddress;
 
                     if (overlapStartsBefore || overlapEndsAfter)
                     {
@@ -321,25 +317,25 @@ namespace Ryujinx.Memory.WindowsShared
                         {
                             partialUnmapState.PartialUnmapsCount++;
 
-                            if (!WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)overlapStart, 2))
+                            if (!WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)overlap.Start, 2))
                             {
                                 throw new WindowsApiException("UnmapViewOfFile2");
                             }
 
                             if (overlapStartsBefore)
                             {
-                                ulong remapSize = startAddress - overlapStart;
+                                ulong remapSize = startAddress - overlap.Start;
 
-                                MapViewInternal(sharedMemory, overlapValue, (IntPtr)overlapStart, (IntPtr)remapSize);
-                                RestoreRangeProtection(overlapStart, remapSize);
+                                MapViewInternal(sharedMemory, overlap.Value, (IntPtr)overlap.Start, (IntPtr)remapSize);
+                                RestoreRangeProtection(overlap.Start, remapSize);
                             }
 
                             if (overlapEndsAfter)
                             {
-                                ulong overlappedSize = endAddress - overlapStart;
-                                ulong remapBackingOffset = overlapValue + overlappedSize;
-                                ulong remapAddress = overlapStart + overlappedSize;
-                                ulong remapSize = overlapEnd - endAddress;
+                                ulong overlappedSize = endAddress - overlap.Start;
+                                ulong remapBackingOffset = overlap.Value + overlappedSize;
+                                ulong remapAddress = overlap.Start + overlappedSize;
+                                ulong remapSize = overlap.End - endAddress;
 
                                 MapViewInternal(sharedMemory, remapBackingOffset, (IntPtr)remapAddress, (IntPtr)remapSize);
                                 RestoreRangeProtection(remapAddress, remapSize);
@@ -350,7 +346,7 @@ namespace Ryujinx.Memory.WindowsShared
                             partialUnmapLock.DowngradeFromWriterLock();
                         }
                     }
-                    else if (!WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)overlapStart, 2))
+                    else if (!WindowsApi.UnmapViewOfFile2(WindowsApi.CurrentProcessHandle, (IntPtr)overlap.Start, 2))
                     {
                         throw new WindowsApiException("UnmapViewOfFile2");
                     }