memblock_free_all释放page到buddy，前后nr_free的情况
https://www.cnblogs.com/tolimit/p/5287801.html
在zone_sizes_init 之后，各个node，zone'的page总数已知。但是此时的每个order的空闲链表是空的，也就是无法通过alloc_page这种接口来分配。此时page还在memblock管控，需要memblock释放。释放的函数是free_low_memory_core_early：
mm_init //init/main.cmem_init(void) //arch/arm64/mm/init.cmemblock_free_all();void __init memblock_free_all(void)
{unsigned long pages;free_unused_memmap();reset_all_zones_managed_pages();pages = free_low_memory_core_early();totalram_pages_add(pages);
}free_low_memory_core_earlyfor_each_free_mem_range__free_memory_core(start, end);__free_pages_memory(start_pfn, end_pfn);memblock_free_pages(pfn_to_page(start), start, order);__free_pages_core__free_pages_ok__free_one_page在memblock_free_all之前，各个NUMA的pglist_data的zone下面不同order的nr_free链表数为0：
[ 0.000000] ===show_mem_info after zone_sizes_init[ 0.000000] ===show_pgdata_info nodeid 0
[ 0.000000] ===show_zone_info :name : DMAmanaged_pages:7a000spanned_pages:80000present_pages:7c000
[ 0.000000] MAX_ORDER 10 of order :0 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :1 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :2 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :3 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :4 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :5 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :6 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :7 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :8 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :9 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :10 has nr_free 0
[ 0.000000] ===show_zone_info :name : DMA32managed_pages:0spanned_pages:0present_pages:0
[ 0.000000] MAX_ORDER 10 of order :0 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :1 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :2 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :3 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :4 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :5 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :6 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :7 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :8 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :9 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :10 has nr_free 0
[ 0.000000] ===show_zone_info :name : Normalmanaged_pages:762000spanned_pages:2680000present_pages:780000
[ 0.000000] MAX_ORDER 10 of order :0 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :1 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :2 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :3 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :4 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :5 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :6 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :7 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :8 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :9 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :10 has nr_free 0
[ 0.000000] ===show_zone_info :name : Movablemanaged_pages:0spanned_pages:0present_pages:0
[ 0.000000] MAX_ORDER 10 of order :0 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :1 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :2 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :3 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :4 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :5 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :6 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :7 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :8 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :9 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :10 has nr_free 0在memblock_free_all之后，才有，特别是order为10的情况最多，这是看空闲的组成大的buddy：
[ 0.000000] ===free_low_mwmory_core_early return pages 7c4864
[ 0.000000] ===show_mem_info after memblock_free_all[ 0.000000] ===show_pgdata_info nodeid 0
[ 0.000000] ===show_zone_info :name : DMAmanaged_pages:6b9f1spanned_pages:80000present_pages:7c000
[ 0.000000] MAX_ORDER 10 of order :0 has nr_free 5
[ 0.000000] MAX_ORDER 10 of order :1 has nr_free 4
[ 0.000000] MAX_ORDER 10 of order :2 has nr_free 5
[ 0.000000] MAX_ORDER 10 of order :3 has nr_free 4
[ 0.000000] MAX_ORDER 10 of order :4 has nr_free b
[ 0.000000] MAX_ORDER 10 of order :5 has nr_free 4
[ 0.000000] MAX_ORDER 10 of order :6 has nr_free 6
[ 0.000000] MAX_ORDER 10 of order :7 has nr_free 6
[ 0.000000] MAX_ORDER 10 of order :8 has nr_free 6
[ 0.000000] MAX_ORDER 10 of order :9 has nr_free 5
[ 0.000000] MAX_ORDER 10 of order :10 has nr_free 1a9
[ 0.000000] ===show_zone_info :name : DMA32managed_pages:0spanned_pages:0present_pages:0
[ 0.000000] MAX_ORDER 10 of order :0 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :1 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :2 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :3 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :4 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :5 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :6 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :7 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :8 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :9 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :10 has nr_free 0
[ 0.000000] ===show_zone_info :name : Normalmanaged_pages:758e73spanned_pages:2680000present_pages:780000
[ 0.000000] MAX_ORDER 10 of order :0 has nr_free 1
[ 0.000000] MAX_ORDER 10 of order :1 has nr_free 1
[ 0.000000] MAX_ORDER 10 of order :2 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :3 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :4 has nr_free 1
[ 0.000000] MAX_ORDER 10 of order :5 has nr_free 1
[ 0.000000] MAX_ORDER 10 of order :6 has nr_free 1
[ 0.000000] MAX_ORDER 10 of order :7 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :8 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :9 has nr_free 1
[ 0.000000] MAX_ORDER 10 of order :10 has nr_free 1d63
[ 0.000000] ===show_zone_info :name : Movablemanaged_pages:0spanned_pages:0present_pages:0
[ 0.000000] MAX_ORDER 10 of order :0 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :1 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :2 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :3 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :4 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :5 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :6 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :7 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :8 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :9 has nr_free 0
[ 0.000000] MAX_ORDER 10 of order :10 has nr_free 0