From 7e4376d46956a272abf548215ec50f400842ac4d Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Sun, 3 Feb 2019 02:32:38 +0100
Subject: [PATCH] Kernel: When entering page_in_from_inode(), assert that
 !physical_page.

It would be really weird to enter here with a physical page already present
in the VMObject's page slot. Let's assert that this doesn't happen.
---
 Kernel/MemoryManager.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Kernel/MemoryManager.cpp b/Kernel/MemoryManager.cpp
index a992bbf519..0c36befbfc 100644
--- a/Kernel/MemoryManager.cpp
+++ b/Kernel/MemoryManager.cpp
@@ -304,6 +304,8 @@ bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_re
 
     auto& vmo_page = vmo.physical_pages()[region.first_page_index() + page_index_in_region];
 
+    ASSERT(vmo_page.is_null());
+
     bool interrupts_were_enabled = are_interrupts_enabled();
 
     if (!interrupts_were_enabled)