diff --git a/mm/cma.c b/mm/cma.c index 20c4f6f40037..0ba69cd16aeb 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -336,6 +336,23 @@ int __init cma_declare_contiguous_nid(phys_addr_t base, limit = highmem_start; } + /* + * If there is enough memory, try a bottom-up allocation first. + * It will place the new cma area close to the start of the node + * and guarantee that the compaction is moving pages out of the + * cma area and not into it. + * Avoid using first 4GB to not interfere with constrained zones + * like DMA/DMA32. + */ +#ifdef CONFIG_PHYS_ADDR_T_64BIT + if (!memblock_bottom_up() && memblock_end >= SZ_4G + size) { + memblock_set_bottom_up(true); + addr = memblock_alloc_range_nid(size, alignment, SZ_4G, + limit, nid, true); + memblock_set_bottom_up(false); + } +#endif + if (!addr) { addr = memblock_alloc_range_nid(size, alignment, base, limit, nid, true);