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Kernel: Memory purging improvements

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This adds the ability for a Region to define volatile/nonvolatile
areas within mapped memory using madvise(). This also means that
memory purging takes into account all views of the PurgeableVMObject
and only purges memory that is not needed by all of them. When calling
madvise() to change an area to nonvolatile memory, return whether
memory from that area was purged. At that time also try to remap
all memory that is requested to be nonvolatile, and if insufficient
pages are available notify the caller of that fact.
This commit is contained in:
Tom 2020-09-02 22:57:09 -06:00 • committed by Andreas Kling
parent cf2c215def
commit bc5d6992a4
14 changed files with 655 additions and 62 deletions
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25
Kernel/VM/Region.h
View file

@ -28,9 +28,11 @@
#include <AK/InlineLinkedList.h>
#include <AK/String.h>
#include <AK/WeakPtr.h>
#include <AK/Weakable.h>
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/Heap/SlabAllocator.h>
#include <Kernel/VM/PurgeableVMObject.h>
#include <Kernel/VM/RangeAllocator.h>
#include <Kernel/VM/VMObject.h>
@ -47,7 +49,8 @@ enum class PageFaultResponse {
class Region final
: public InlineLinkedListNode<Region>
, public Weakable<Region> {
, public Weakable<Region>
, public PurgeablePageRanges {
friend class MemoryManager;
MAKE_SLAB_ALLOCATED(Region)
@ -63,7 +66,7 @@ public:
ZeroedOnFork,
};
static NonnullOwnPtr<Region> create_user_accessible(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable = true);
static NonnullOwnPtr<Region> create_user_accessible(Process*, const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable = true);
static NonnullOwnPtr<Region> create_kernel_only(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const StringView& name, u8 access, bool cacheable = true);
~Region();
@ -83,7 +86,7 @@ public:
const VMObject& vmobject() const { return *m_vmobject; }
VMObject& vmobject() { return *m_vmobject; }
void set_vmobject(NonnullRefPtr<VMObject>&& obj) { m_vmobject = obj; }
void set_vmobject(NonnullRefPtr<VMObject>&&);
bool is_shared() const { return m_shared; }
void set_shared(bool shared) { m_shared = shared; }
@ -190,6 +193,18 @@ public:
void set_inherit_mode(InheritMode inherit_mode) { m_inherit_mode = inherit_mode; }
bool remap_page_range(size_t page_index, size_t page_count);
bool is_volatile(VirtualAddress vaddr, size_t size) const;
enum class SetVolatileError {
Success = 0,
NotPurgeable,
OutOfMemory
};
SetVolatileError set_volatile(VirtualAddress vaddr, size_t size, bool is_volatile, bool& was_purged);
RefPtr<Process> get_owner();
private:
Bitmap& ensure_cow_map() const;
@ -210,6 +225,9 @@ private:
bool map_individual_page_impl(size_t page_index);
void register_purgeable_page_ranges();
void unregister_purgeable_page_ranges();
RefPtr<PageDirectory> m_page_directory;
Range m_range;
size_t m_offset_in_vmobject { 0 };
@ -224,6 +242,7 @@ private:
bool m_mmap : 1 { false };
bool m_kernel : 1 { false };
mutable OwnPtr<Bitmap> m_cow_map;
WeakPtr<Process> m_owner;
};
inline unsigned prot_to_region_access_flags(int prot)