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Kernel: More gracefully handle out-of-memory when creating PageDirectory

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Tom 2020-09-27 08:10:10 -06:00 • committed by Andreas Kling
parent ae956edf6e
commit bf9be3ec01
3 changed files with 23 additions and 5 deletions
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15
Kernel/VM/PageDirectory.cpp
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@ -74,7 +74,6 @@ PageDirectory::PageDirectory()
}
PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_range_allocator)
: m_process(&process)
{
ScopedSpinLock lock(s_mm_lock);
if (parent_range_allocator) {
@ -87,9 +86,17 @@ PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_rang
// Set up a userspace page directory
m_directory_table = MM.allocate_user_physical_page();
if (!m_directory_table)
return;
m_directory_pages[0] = MM.allocate_user_physical_page();
if (!m_directory_pages[0])
return;
m_directory_pages[1] = MM.allocate_user_physical_page();
if (!m_directory_pages[1])
return;
m_directory_pages[2] = MM.allocate_user_physical_page();
if (!m_directory_pages[2])
return;
// Share the top 1 GiB of kernel-only mappings (>=3GiB or >=0xc0000000)
m_directory_pages[3] = MM.kernel_page_directory().m_directory_pages[3];
@ -135,6 +142,9 @@ PageDirectory::PageDirectory(Process& process, const RangeAllocator* parent_rang
auto* new_pd = MM.quickmap_pd(*this, 0);
memcpy(new_pd, &buffer, sizeof(PageDirectoryEntry));
// If we got here, we successfully created it. Set m_process now
m_process = &process;
cr3_map().set(cr3(), this);
}
@ -144,7 +154,8 @@ PageDirectory::~PageDirectory()
dbg() << "MM: ~PageDirectory K" << this;
#endif
ScopedSpinLock lock(s_mm_lock);
cr3_map().remove(cr3());
if (m_process)
cr3_map().remove(cr3());
}
}