Kernel: Remove pointless ref-counting from PhysicalRegion

These are not multiple-owner objects and have no use for ref-counting.
Make them simple value types instead (not eternal heap-allocated.)

Kernel/VM/MemoryManager.cpp

@@ -174,7 +174,7 @@ bool MemoryManager::is_allowed_to_mmap_to_userspace(PhysicalAddress start_addres
 
 UNMAP_AFTER_INIT void MemoryManager::parse_memory_map()
 {
-    RefPtr<PhysicalRegion> physical_region;
+    PhysicalRegion* physical_region { nullptr };
 
     // Register used memory regions that we know of.
     m_used_memory_ranges.ensure_capacity(4);
@@ -256,9 +256,9 @@ UNMAP_AFTER_INIT void MemoryManager::parse_memory_map()
                 continue;
 
             // Assign page to user physical physical_region.
-            if (physical_region.is_null() || physical_region->upper().offset(PAGE_SIZE) != addr) {
+            if (!physical_region || physical_region->upper().offset(PAGE_SIZE) != addr) {
                 m_user_physical_regions.append(PhysicalRegion::create(addr, addr));
-                physical_region = m_user_physical_regions.last();
+                physical_region = &m_user_physical_regions.last();
             } else {
                 physical_region->expand(physical_region->lower(), addr);
             }
@@ -336,10 +336,10 @@ UNMAP_AFTER_INIT void MemoryManager::initialize_physical_pages()
     auto physical_page_array_pages_and_page_tables_count = physical_page_array_pages + needed_page_table_count;
 
     // Now that we know how much memory we need for a contiguous array of PhysicalPage instances, find a memory region that can fit it
-    RefPtr<PhysicalRegion> found_region;
+    PhysicalRegion* found_region { nullptr };
     for (auto& region : m_user_physical_regions) {
         if (region.size() >= physical_page_array_pages_and_page_tables_count) {
-            found_region = region;
+            found_region = &region;
             break;
         }
     }
@@ -354,10 +354,10 @@ UNMAP_AFTER_INIT void MemoryManager::initialize_physical_pages()
 
     if (found_region->size() == physical_page_array_pages_and_page_tables_count) {
         // We're stealing the entire region
+        m_physical_pages_region = move(*found_region);
         m_user_physical_regions.remove_first_matching([&](auto& region) {
-            return region == found_region.ptr();
+            return &region == found_region;
         });
-        m_physical_pages_region = found_region.release_nonnull();
     } else {
         m_physical_pages_region = found_region->take_pages_from_beginning(physical_page_array_pages_and_page_tables_count);
     }

Kernel/VM/MemoryManager.h

@@ -16,6 +16,7 @@
 #include <Kernel/SpinLock.h>
 #include <Kernel/VM/AllocationStrategy.h>
 #include <Kernel/VM/PhysicalPage.h>
+#include <Kernel/VM/PhysicalRegion.h>
 #include <Kernel/VM/Region.h>
 #include <Kernel/VM/VMObject.h>
 
@@ -245,9 +246,9 @@ private:
 
     SystemMemoryInfo m_system_memory_info;
 
-    NonnullRefPtrVector<PhysicalRegion> m_user_physical_regions;
-    NonnullRefPtrVector<PhysicalRegion> m_super_physical_regions;
-    RefPtr<PhysicalRegion> m_physical_pages_region;
+    Vector<PhysicalRegion> m_user_physical_regions;
+    Vector<PhysicalRegion> m_super_physical_regions;
+    Optional<PhysicalRegion> m_physical_pages_region;
     PhysicalPageEntry* m_physical_page_entries { nullptr };
     size_t m_physical_page_entries_free { 0 };
     size_t m_physical_page_entries_count { 0 };

Kernel/VM/PhysicalRegion.cpp

@@ -4,22 +4,14 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/Bitmap.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefPtr.h>
-#include <AK/Vector.h>
 #include <Kernel/Assertions.h>
 #include <Kernel/Random.h>
-#include <Kernel/VM/PhysicalPage.h>
 #include <Kernel/VM/PhysicalRegion.h>
 
 namespace Kernel {
 
-NonnullRefPtr<PhysicalRegion> PhysicalRegion::create(PhysicalAddress lower, PhysicalAddress upper)
-{
-    return adopt_ref(*new PhysicalRegion(lower, upper));
-}
-
 PhysicalRegion::PhysicalRegion(PhysicalAddress lower, PhysicalAddress upper)
     : m_lower(lower)
     , m_upper(upper)
@@ -44,7 +36,7 @@ unsigned PhysicalRegion::finalize_capacity()
     return size();
 }
 
-NonnullRefPtr<PhysicalRegion> PhysicalRegion::take_pages_from_beginning(unsigned page_count)
+PhysicalRegion PhysicalRegion::take_pages_from_beginning(unsigned page_count)
 {
     VERIFY(m_used == 0);
     VERIFY(page_count > 0);
@@ -59,7 +51,7 @@ NonnullRefPtr<PhysicalRegion> PhysicalRegion::take_pages_from_beginning(unsigned
     finalize_capacity();
 
     auto taken_region = create(taken_lower, taken_upper);
-    taken_region->finalize_capacity();
+    taken_region.finalize_capacity();
     return taken_region;
 }
 

Kernel/VM/PhysicalRegion.h

@@ -7,19 +7,17 @@
 #pragma once
 
 #include <AK/Bitmap.h>
-#include <AK/NonnullRefPtrVector.h>
 #include <AK/Optional.h>
-#include <AK/RefCounted.h>
 #include <Kernel/VM/PhysicalPage.h>
 
 namespace Kernel {
 
-class PhysicalRegion : public RefCounted<PhysicalRegion> {
-    AK_MAKE_ETERNAL
-
+class PhysicalRegion {
 public:
-    static NonnullRefPtr<PhysicalRegion> create(PhysicalAddress lower, PhysicalAddress upper);
-    ~PhysicalRegion() = default;
+    static PhysicalRegion create(PhysicalAddress lower, PhysicalAddress upper)
+    {
+        return { lower, upper };
+    }
 
     void expand(PhysicalAddress lower, PhysicalAddress upper);
     unsigned finalize_capacity();
@@ -31,7 +29,7 @@ public:
     unsigned free() const { return m_pages - m_used + m_recently_returned.size(); }
     bool contains(PhysicalAddress paddr) const { return paddr >= m_lower && paddr <= m_upper; }
 
-    NonnullRefPtr<PhysicalRegion> take_pages_from_beginning(unsigned);
+    PhysicalRegion take_pages_from_beginning(unsigned);
 
     RefPtr<PhysicalPage> take_free_page(bool supervisor);
     NonnullRefPtrVector<PhysicalPage> take_contiguous_free_pages(size_t count, bool supervisor, size_t physical_alignment = PAGE_SIZE);
@@ -41,7 +39,7 @@ private:
     unsigned find_contiguous_free_pages(size_t count, size_t physical_alignment = PAGE_SIZE);
     Optional<unsigned> find_and_allocate_contiguous_range(size_t count, unsigned alignment = 1);
     Optional<unsigned> find_one_free_page();
-    void free_page_at(PhysicalAddress addr);
+    void free_page_at(PhysicalAddress);
 
     PhysicalRegion(PhysicalAddress lower, PhysicalAddress upper);