From 4d2f1a05ecc8d6e1c1573d2013eebb87d91dc83b Mon Sep 17 00:00:00 2001
From: Idan Horowitz <idan.horowitz@gmail.com>
Date: Fri, 28 Jan 2022 16:23:24 +0200
Subject: Kernel: Make allocate_contiguous_supervisor_physical_pages
 OOM-fallible

---
 Kernel/Memory/AnonymousVMObject.cpp |  4 +---
 Kernel/Memory/MemoryManager.cpp     | 17 +++++------------
 Kernel/Memory/MemoryManager.h       |  2 +-
 3 files changed, 7 insertions(+), 16 deletions(-)

(limited to 'Kernel')

diff --git a/Kernel/Memory/AnonymousVMObject.cpp b/Kernel/Memory/AnonymousVMObject.cpp
index ad3465e732..fe7471bcfc 100644
--- a/Kernel/Memory/AnonymousVMObject.cpp
+++ b/Kernel/Memory/AnonymousVMObject.cpp
@@ -81,9 +81,7 @@ ErrorOr<NonnullRefPtr<AnonymousVMObject>> AnonymousVMObject::try_create_with_siz
 
 ErrorOr<NonnullRefPtr<AnonymousVMObject>> AnonymousVMObject::try_create_physically_contiguous_with_size(size_t size)
 {
-    auto contiguous_physical_pages = MM.allocate_contiguous_supervisor_physical_pages(size);
-    if (contiguous_physical_pages.is_empty())
-        return ENOMEM;
+    auto contiguous_physical_pages = TRY(MM.allocate_contiguous_supervisor_physical_pages(size));
 
     auto new_physical_pages = TRY(FixedArray<RefPtr<PhysicalPage>>::try_create(contiguous_physical_pages.span()));
 
diff --git a/Kernel/Memory/MemoryManager.cpp b/Kernel/Memory/MemoryManager.cpp
index 1b72cc4d24..670b5123d7 100644
--- a/Kernel/Memory/MemoryManager.cpp
+++ b/Kernel/Memory/MemoryManager.cpp
@@ -759,12 +759,9 @@ ErrorOr<NonnullOwnPtr<Memory::Region>> MemoryManager::allocate_dma_buffer_page(S
 ErrorOr<NonnullOwnPtr<Memory::Region>> MemoryManager::allocate_dma_buffer_pages(size_t size, StringView name, Memory::Region::Access access, NonnullRefPtrVector<Memory::PhysicalPage>& dma_buffer_pages)
 {
     VERIFY(!(size % PAGE_SIZE));
-    dma_buffer_pages = allocate_contiguous_supervisor_physical_pages(size);
-    if (dma_buffer_pages.is_empty())
-        return ENOMEM;
+    dma_buffer_pages = TRY(allocate_contiguous_supervisor_physical_pages(size));
     // 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_pages.first().paddr(), size, name, access, Region::Cacheable::No);
-    return region_or_error;
+    return allocate_kernel_region(dma_buffer_pages.first().paddr(), size, name, access, Region::Cacheable::No);
 }
 
 ErrorOr<NonnullOwnPtr<Memory::Region>> MemoryManager::allocate_dma_buffer_pages(size_t size, StringView name, Memory::Region::Access access)
@@ -939,7 +936,7 @@ RefPtr<PhysicalPage> MemoryManager::allocate_user_physical_page(ShouldZeroFill s
     return page;
 }
 
-NonnullRefPtrVector<PhysicalPage> MemoryManager::allocate_contiguous_supervisor_physical_pages(size_t size)
+ErrorOr<NonnullRefPtrVector<PhysicalPage>> MemoryManager::allocate_contiguous_supervisor_physical_pages(size_t size)
 {
     VERIFY(!(size % PAGE_SIZE));
     SpinlockLocker lock(s_mm_lock);
@@ -948,15 +945,11 @@ NonnullRefPtrVector<PhysicalPage> MemoryManager::allocate_contiguous_supervisor_
 
     if (physical_pages.is_empty()) {
         dmesgln("MM: no super physical pages available");
-        VERIFY_NOT_REACHED();
-        return {};
+        return ENOMEM;
     }
 
     {
-        auto region_or_error = MM.allocate_kernel_region(physical_pages[0].paddr(), PAGE_SIZE * count, "MemoryManager Allocation Sanitization", Region::Access::Read | Region::Access::Write);
-        if (region_or_error.is_error())
-            TODO();
-        auto cleanup_region = region_or_error.release_value();
+        auto cleanup_region = TRY(MM.allocate_kernel_region(physical_pages[0].paddr(), PAGE_SIZE * count, "MemoryManager Allocation Sanitization", Region::Access::Read | Region::Access::Write));
         memset(cleanup_region->vaddr().as_ptr(), 0, PAGE_SIZE * count);
     }
     m_system_memory_info.super_physical_pages_used += count;
diff --git a/Kernel/Memory/MemoryManager.h b/Kernel/Memory/MemoryManager.h
index 9ccf422115..0020a77d6e 100644
--- a/Kernel/Memory/MemoryManager.h
+++ b/Kernel/Memory/MemoryManager.h
@@ -173,7 +173,7 @@ 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();
-    NonnullRefPtrVector<PhysicalPage> allocate_contiguous_supervisor_physical_pages(size_t size);
+    ErrorOr<NonnullRefPtrVector<PhysicalPage>> allocate_contiguous_supervisor_physical_pages(size_t size);
     void deallocate_physical_page(PhysicalAddress);
 
     ErrorOr<NonnullOwnPtr<Region>> allocate_contiguous_kernel_region(size_t, StringView name, Region::Access access, Region::Cacheable = Region::Cacheable::Yes);
-- 
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