memblock_free_all释放page到buddy，前后nr

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.c
	mem_init(void)   //arch/arm64/mm/init.c
		memblock_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_early
	for_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 : DMA
                      managed_pages:7a000
                      spanned_pages:80000
                      present_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 : DMA32
                      managed_pages:0
                      spanned_pages:0
                      present_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 : Normal
                      managed_pages:762000
                      spanned_pages:2680000
                      present_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 : Movable
                      managed_pages:0
                      spanned_pages:0
                      present_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 : DMA
                      managed_pages:6b9f1
                      spanned_pages:80000
                      present_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 : DMA32
                      managed_pages:0
                      spanned_pages:0
                      present_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 : Normal
                      managed_pages:758e73
                      spanned_pages:2680000
                      present_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 : Movable
                      managed_pages:0
                      spanned_pages:0
                      present_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

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