From: Mike Rapoport <rppt@xxxxxxxxxxxxx> 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> --- mm/memblock.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/mm/memblock.c b/mm/memblock.c index afaefa8fc6ab..97fa87541b5f 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1943,11 +1943,11 @@ static void __init free_unused_memmap(void) start = min(start, 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 /* @@ -1958,11 +1958,11 @@ 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(end, MAX_ORDER_NR_PAGES); + prev_end = ALIGN(end, pageblock_nr_pages); } #ifdef CONFIG_SPARSEMEM -- 2.28.0
