Kernel: Make allocate_supervisor_physical_page OOM-fallible

Author: https://github.com/IdanHo
Commit: https://github.com/SerenityOS/serenity/commit/bd5b56cab0a
Pull-request: https://github.com/SerenityOS/serenity/pull/12179

Kernel/Memory/MemoryManager.cpp

@@ -741,12 +741,9 @@ ErrorOr<NonnullOwnPtr<Region>> MemoryManager::allocate_contiguous_kernel_region(
 
 ErrorOr<NonnullOwnPtr<Memory::Region>> MemoryManager::allocate_dma_buffer_page(StringView name, Memory::Region::Access access, RefPtr<Memory::PhysicalPage>& dma_buffer_page)
 {
-    dma_buffer_page = allocate_supervisor_physical_page();
-    if (dma_buffer_page.is_null())
-        return ENOMEM;
+    dma_buffer_page = TRY(allocate_supervisor_physical_page());
     // Do not enable Cache for this region as physical memory transfers are performed (Most architectures have this behaviour by default)
-    auto region_or_error = allocate_kernel_region(dma_buffer_page->paddr(), PAGE_SIZE, name, access, Region::Cacheable::No);
-    return region_or_error;
+    return allocate_kernel_region(dma_buffer_page->paddr(), PAGE_SIZE, name, access, Region::Cacheable::No);
 }
 
 ErrorOr<NonnullOwnPtr<Memory::Region>> MemoryManager::allocate_dma_buffer_page(StringView name, Memory::Region::Access access)
@@ -956,22 +953,21 @@ ErrorOr<NonnullRefPtrVector<PhysicalPage>> MemoryManager::allocate_contiguous_su
     return physical_pages;
 }
 
-RefPtr<PhysicalPage> MemoryManager::allocate_supervisor_physical_page()
+ErrorOr<NonnullRefPtr<PhysicalPage>> MemoryManager::allocate_supervisor_physical_page()
 {
     SpinlockLocker lock(s_mm_lock);
     auto page = m_super_physical_region->take_free_page();
 
     if (!page) {
         dmesgln("MM: no super physical pages available");
-        VERIFY_NOT_REACHED();
-        return {};
+        return ENOMEM;
     }
 
     auto* ptr = quickmap_page(*page);
     memset(ptr, 0, PAGE_SIZE);
     unquickmap_page();
     ++m_system_memory_info.super_physical_pages_used;
-    return page;
+    return page.release_nonnull();
 }
 
 void MemoryManager::enter_process_address_space(Process& process)

Kernel/Memory/MemoryManager.h

@@ -172,7 +172,7 @@ public:
 
     NonnullRefPtr<PhysicalPage> allocate_committed_user_physical_page(Badge<CommittedPhysicalPageSet>, ShouldZeroFill = ShouldZeroFill::Yes);
     RefPtr<PhysicalPage> allocate_user_physical_page(ShouldZeroFill = ShouldZeroFill::Yes, bool* did_purge = nullptr);
-    RefPtr<PhysicalPage> allocate_supervisor_physical_page();
+    ErrorOr<NonnullRefPtr<PhysicalPage>> allocate_supervisor_physical_page();
     ErrorOr<NonnullRefPtrVector<PhysicalPage>> allocate_contiguous_supervisor_physical_pages(size_t size);
     void deallocate_physical_page(PhysicalAddress);
 

Kernel/Storage/ATA/AHCIPort.cpp

@@ -37,25 +37,19 @@ AHCIPort::AHCIPort(const AHCIPortHandler& handler, volatile AHCI::PortRegisters&
         return;
     }
 
-    m_fis_receive_page = MM.allocate_supervisor_physical_page();
-    if (m_fis_receive_page.is_null())
-        return;
+    m_fis_receive_page = MM.allocate_supervisor_physical_page().release_value_but_fixme_should_propagate_errors();
 
     for (size_t index = 0; index < 1; index++) {
-        m_dma_buffers.append(MM.allocate_supervisor_physical_page().release_nonnull());
+        m_dma_buffers.append(MM.allocate_supervisor_physical_page().release_value_but_fixme_should_propagate_errors());
     }
     for (size_t index = 0; index < 1; index++) {
-        m_command_table_pages.append(MM.allocate_supervisor_physical_page().release_nonnull());
+        m_command_table_pages.append(MM.allocate_supervisor_physical_page().release_value_but_fixme_should_propagate_errors());
     }
 
-    auto region_or_error = MM.allocate_dma_buffer_page("AHCI Port Command List", Memory::Region::Access::ReadWrite, m_command_list_page);
+    m_command_list_region = MM.allocate_dma_buffer_page("AHCI Port Command List", Memory::Region::Access::ReadWrite, m_command_list_page).release_value_but_fixme_should_propagate_errors();
 
     dbgln_if(AHCI_DEBUG, "AHCI Port {}: Command list page at {}", representative_port_index(), m_command_list_page->paddr());
     dbgln_if(AHCI_DEBUG, "AHCI Port {}: FIS receive page at {}", representative_port_index(), m_fis_receive_page->paddr());
-
-    if (region_or_error.is_error())
-        TODO();
-    m_command_list_region = region_or_error.release_value();
     dbgln_if(AHCI_DEBUG, "AHCI Port {}: Command list region at {}", representative_port_index(), m_command_list_region->vaddr());
 }
 

Kernel/Storage/ATA/AHCIPortHandler.cpp

@@ -22,7 +22,7 @@ AHCIPortHandler::AHCIPortHandler(AHCIController& controller, u8 irq, AHCI::Maske
 {
     // FIXME: Use the number of taken ports to determine how many pages we should allocate.
     for (size_t index = 0; index < (((size_t)AHCI::Limits::MaxPorts * 512) / PAGE_SIZE); index++) {
-        m_identify_metadata_pages.append(MM.allocate_supervisor_physical_page().release_nonnull());
+        m_identify_metadata_pages.append(MM.allocate_supervisor_physical_page().release_value_but_fixme_should_propagate_errors());
     }
 
     dbgln_if(AHCI_DEBUG, "AHCI Port Handler: IRQ {}", irq);