From: Mike Rapoport <rppt@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx> Tested-by: Tony Lindgren <tony@xxxxxxxxxxx> Link: https://lore.kernel.org/lkml/20210630071211.21011-1-rppt@xxxxxxxxxx/ [backport upstream modification in mm/memblock.c to arch/arm/mm/init.c] Signed-off-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm/mm/init.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -373,11 +373,11 @@ static void __init free_unused_memmap(vo 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(vo 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
