Kernel: Store VMObject physical pages in a FixedArray

Let's enforce the invariant that VMObjects don't shrink or grow by
storing the pages in a FixedArray.

3 files changed, 6 insertions, 11 deletions

diff --git a/Kernel/VM/AnonymousVMObject.cpp b/Kernel/VM/AnonymousVMObject.cpp
index 9b479f8e51..01cd64ae51 100644
--- a/Kernel/VM/AnonymousVMObject.cpp
+++ b/Kernel/VM/AnonymousVMObject.cpp
@@ -117,11 +117,11 @@ AnonymousVMObject::AnonymousVMObject(PhysicalPage& page)
 }
 
 AnonymousVMObject::AnonymousVMObject(NonnullRefPtrVector<PhysicalPage> physical_pages)
-    : VMObject()
+    : VMObject(physical_pages.size())
     , m_volatile_ranges_cache({ 0, page_count() })
 {
-    for (auto& page : physical_pages) {
-        m_physical_pages.append(page);
+    for (size_t i = 0; i < physical_pages.size(); ++i) {
+        m_physical_pages[i] = physical_pages[i];
     }
 }
 
diff --git a/Kernel/VM/VMObject.cpp b/Kernel/VM/VMObject.cpp
index 5908b4a7ce..99cf074b9c 100644
--- a/Kernel/VM/VMObject.cpp
+++ b/Kernel/VM/VMObject.cpp
@@ -15,14 +15,9 @@ VMObject::VMObject(const VMObject& other)
     MM.register_vmobject(*this);
 }
 
-VMObject::VMObject()
-{
-    MM.register_vmobject(*this);
-}
-
 VMObject::VMObject(size_t size)
+    : m_physical_pages(ceil_div(size, static_cast<size_t>(PAGE_SIZE)))
 {
-    m_physical_pages.resize(ceil_div(size, static_cast<size_t>(PAGE_SIZE)));
     MM.register_vmobject(*this);
 }
 
diff --git a/Kernel/VM/VMObject.h b/Kernel/VM/VMObject.h
index 58ae7276c3..4cdd64c9c6 100644
--- a/Kernel/VM/VMObject.h
+++ b/Kernel/VM/VMObject.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/FixedArray.h>
 #include <AK/HashTable.h>
 #include <AK/IntrusiveList.h>
 #include <AK/RefCounted.h>
@@ -61,7 +62,6 @@ public:
     }
 
 protected:
-    VMObject();
     explicit VMObject(size_t);
     explicit VMObject(const VMObject&);
 
@@ -69,7 +69,7 @@ protected:
     void for_each_region(Callback);
 
     IntrusiveListNode<VMObject> m_list_node;
-    Vector<RefPtr<PhysicalPage>, 16> m_physical_pages;
+    FixedArray<RefPtr<PhysicalPage>> m_physical_pages;
     Lock m_paging_lock { "VMObject" };
 
     mutable SpinLock<u8> m_lock;