From b29a83d554200182bd1bfb41b08e601c7944c4df Mon Sep 17 00:00:00 2001
From: Conrad Pankoff <deoxxa@fknsrs.biz>
Date: Wed, 12 Jun 2019 23:31:14 +1000
Subject: [PATCH] Kernel: Wrap around to region start if necessary in
 take_free_page

---
 Kernel/VM/PhysicalRegion.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Kernel/VM/PhysicalRegion.cpp b/Kernel/VM/PhysicalRegion.cpp
index 4743d1b59d..fd7021d977 100644
--- a/Kernel/VM/PhysicalRegion.cpp
+++ b/Kernel/VM/PhysicalRegion.cpp
@@ -43,6 +43,7 @@ RetainPtr<PhysicalPage> PhysicalRegion::take_free_page(bool supervisor)
     if (m_used == m_pages)
         return nullptr;
 
+    // search from the last page we allocated
     for (unsigned page = m_last; page < m_pages; page++) {
         if (!m_bitmap.get(page)) {
             m_bitmap.set(page, true);
@@ -52,6 +53,16 @@ RetainPtr<PhysicalPage> PhysicalRegion::take_free_page(bool supervisor)
         }
     }
 
+    // wrap back around to the start in case we missed something
+    for (unsigned page = 0; page < m_last; page++) {
+        if (!m_bitmap.get(page)) {
+            m_bitmap.set(page, true);
+            m_used++;
+            m_last = page + 1;
+            return PhysicalPage::create(m_lower.offset(page * PAGE_SIZE), supervisor);
+        }
+    }
+
     ASSERT_NOT_REACHED();
 
     return nullptr;