Commit 60111b30 authored Dec 13, 2021 by Mike Rapoport Committed by Greg Kroah-Hartman Dec 17, 2021

memblock: free_unused_memmap: use pageblock units instead of MAX_ORDER



commit e2a86800d58639b3acde7eaeb9eb393dca066e08 upstream.

The code that frees unused memory map uses rounds start and end of the
holes that are freed to MAX_ORDER_NR_PAGES to preserve continuity of the
memory map for MAX_ORDER regions.

Lots of core memory management functionality relies on homogeneity of the
memory map within each pageblock which size may differ from MAX_ORDER in
certain configurations.

Although currently, for the architectures that use free_unused_memmap(),
pageblock_order and MAX_ORDER are equivalent, it is cleaner to have common
notation thought mm code.

Replace MAX_ORDER_NR_PAGES with pageblock_nr_pages and update the comments
to make it more clear why the alignment to pageblock boundaries is
required.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/lkml/20210630071211.21011-1-rppt@kernel.org/


[backport upstream modification in mm/memblock.c to arch/arm/mm/init.c]
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 3e8e2728

arch/arm/mm/init.c

+8 −8

Original line number	Diff line number	Diff line
		@@ -373,11 +373,11 @@ static void __init free_unused_memmap(void)
		ALIGN(prev_end, PAGES_PER_SECTION));
		#else
		/*
		* Align down here since the VM subsystem insists that the
		* memmap entries are valid from the bank start aligned to
		* MAX_ORDER_NR_PAGES.
		* Align down here since many operations in VM subsystem
		* presume that there are no holes in the memory map inside
		* a pageblock
		*/
		start = round_down(start, MAX_ORDER_NR_PAGES);
		start = round_down(start, pageblock_nr_pages);
		#endif
		/*
		* If we had a previous bank, and there is a space
		@@ -387,12 +387,12 @@ static void __init free_unused_memmap(void)
		free_memmap(prev_end, start);

		/*
		* Align up here since the VM subsystem insists that the
		* memmap entries are valid from the bank end aligned to
		* MAX_ORDER_NR_PAGES.
		* Align up here since many operations in VM subsystem
		* presume that there are no holes in the memory map inside
		* a pageblock
		*/
		prev_end = ALIGN(memblock_region_memory_end_pfn(reg),
		MAX_ORDER_NR_PAGES);
		pageblock_nr_pages);
		}

		#ifdef CONFIG_SPARSEMEM