diff --git a/include/asm.h b/include/asm.h
index 4694222..15f8bc5 100644
--- a/include/asm.h
+++ b/include/asm.h
@@ -136,6 +136,11 @@ static inline ulong KeReadStsc(void) {
     return ((ulong)edx << 32) + eax;
 }
 
+static inline void KeFlushTlbSingle(unsigned long addr)
+{
+   asm volatile("invlpg (%0)" ::"r" (addr) : "memory");
+}
+
 //------------------------------------------//
 //                Misc. I/O                 //
 //------------------------------------------//
diff --git a/include/mm/mm.h b/include/mm/mm.h
index 283f262..ed0e57a 100644
--- a/include/mm/mm.h
+++ b/include/mm/mm.h
@@ -41,7 +41,7 @@
 #define BADRAM_ZONE       5     // Invalid zone because material problem...
 #define MAX_ENTRIES       2048  // Max number of memory map entries
 #define KPAGESIZE (4 * KB)
-#define UPAGESIZE (2 * MB)
+#define UPAGESIZE (4 * KB)
 
 //----------------------------------------------------------------------------//
 
diff --git a/kaleid/kernel/ke/isr.asm b/kaleid/kernel/ke/isr.asm
index 43b5374..7c07e6f 100644
--- a/kaleid/kernel/ke/isr.asm
+++ b/kaleid/kernel/ke/isr.asm
@@ -58,10 +58,11 @@ isrPreHandler:
     push rax
 
     ; Check if we are switching from user mode to supervisor mode
-    ;mov rax, [rsp + 152]
-    ;and rax, 0x3000
-    ;jz .SEnter
-    ;swapgs ; XXX need TSS
+    mov rax, [rsp + 152]
+    and rax, 0x3000
+    jz .SEnter
+
+    swapgs ; XXX need TSS
 
 .SEnter:
     ; Increment mask count as we configure all interrupts to mask IF