ARM64: mm: Restore memblock limit when map_mem finished. (f6bc87c3) · Commits · 戴 / test

In paging_init the memblock limit is set to restrict any addresses returned by early_alloc to fit within the initial direct kernel mapping in swapper_pg_dir. This allows map_mem to allocate puds, pmds and ptes from the initial direct kernel mapping. The limit stays low after paging_init() though, meaning any bootmem allocations will be from a restricted subset of memory. Gigabyte huge pages, for instance, are normally allocated from bootmem as their order (18) is too large for the default buddy allocator (MAX_ORDER = 11). This patch restores the memblock limit when map_mem has finished, allowing gigabyte huge pages (and other objects) to be allocated from all of bootmem. Signed-off-by:

Steve Capper <steve.capper@linaro.org> Acked-by:

Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/mm/mmu.c

+13 −6

Original line number	Diff line number	Diff line
		@@ -297,6 +297,16 @@ static void __init map_mem(void)
		{
		struct memblock_region *reg;

		/*
		* Temporarily limit the memblock range. We need to do this as
		* create_mapping requires puds, pmds and ptes to be allocated from
		* memory addressable from the initial direct kernel mapping.
		*
		* The initial direct kernel mapping, located at swapper_pg_dir,
		* gives us PGDIR_SIZE memory starting from PHYS_OFFSET (aligned).
		*/
		memblock_set_current_limit((PHYS_OFFSET & PGDIR_MASK) + PGDIR_SIZE);

		/* map all the memory banks */
		for_each_memblock(memory, reg) {
		phys_addr_t start = reg->base;
		@@ -307,6 +317,9 @@ static void __init map_mem(void)

		create_mapping(start, __phys_to_virt(start), end - start);
		}

		/* Limit no longer required. */
		memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);
		}

		/*
		@@ -317,12 +330,6 @@ void __init paging_init(void)
		{
		void *zero_page;

		/*
		* Maximum PGDIR_SIZE addressable via the initial direct kernel
		* mapping in swapper_pg_dir.
		*/
		memblock_set_current_limit((PHYS_OFFSET & PGDIR_MASK) + PGDIR_SIZE);

		init_mem_pgprot();
		map_mem();

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