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f7a4c34929
Previously, the heap expansion logic could end up calling kmalloc recursively, which was quite messy and hard to reason about. This patch redesigns heap expansion so that it's kmalloc-free: - We make a single large virtual range allocation at startup - When expanding, we bump allocate VM from that region - When expanding, we populate page tables directly ourselves, instead of going via MemoryManager. This makes heap expansion a great deal simpler. However, do note that it introduces two new flaws that we'll need to deal with eventually: - The single virtual range allocation is limited to 64 MiB and once exhausted, kmalloc() will fail. (Actually, it will PANIC for now..) - The kmalloc heap can no longer shrink once expanded. Subheaps stay in place once constructed.