Re: [PATCH v2 2/2] mm/sparse: start using sparse_init_nid(), and remove old code

From: Baoquan He
Date: Sun Jul 01 2018 - 21:39:32 EST


On 06/29/18 at 11:09pm, Pavel Tatashin wrote:
> Change sprase_init() to only find the pnum ranges that belong to a specific
> node and call sprase_init_nid() for that range from sparse_init().
>
> Delete all the code that became obsolete with this change.
> void __init sparse_init(void)
> {
> - unsigned long pnum;
> - struct page *map;
> - struct page **map_map;
> - unsigned long *usemap;
> - unsigned long **usemap_map;
> - int size, size2;
> - int nr_consumed_maps = 0;
> -
> - /* see include/linux/mmzone.h 'struct mem_section' definition */
> - BUILD_BUG_ON(!is_power_of_2(sizeof(struct mem_section)));
> + unsigned long pnum_begin = first_present_section_nr();
> + int nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
> + unsigned long pnum_end, map_count = 1;
>
> - /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
> - set_pageblock_order();
> + for_each_present_section_nr(pnum_begin + 1, pnum_end) {
> + int nid = sparse_early_nid(__nr_to_section(pnum_end));
>
> - /*
> - * map is using big page (aka 2M in x86 64 bit)
> - * usemap is less one page (aka 24 bytes)
> - * so alloc 2M (with 2M align) and 24 bytes in turn will
> - * make next 2M slip to one more 2M later.
> - * then in big system, the memory will have a lot of holes...
> - * here try to allocate 2M pages continuously.
> - *
> - * powerpc need to call sparse_init_one_section right after each
> - * sparse_early_mem_map_alloc, so allocate usemap_map at first.
> - */
> - size = sizeof(unsigned long *) * nr_present_sections;
> - usemap_map = memblock_virt_alloc(size, 0);
> - if (!usemap_map)
> - panic("can not allocate usemap_map\n");
> - alloc_usemap_and_memmap(sparse_early_usemaps_alloc_node,
> - (void *)usemap_map,
> - sizeof(usemap_map[0]));
> -
> - size2 = sizeof(struct page *) * nr_present_sections;
> - map_map = memblock_virt_alloc(size2, 0);
> - if (!map_map)
> - panic("can not allocate map_map\n");
> - alloc_usemap_and_memmap(sparse_early_mem_maps_alloc_node,
> - (void *)map_map,
> - sizeof(map_map[0]));
> -
> - /* The numner of present sections stored in nr_present_sections
> - * are kept the same since mem sections are marked as present in
> - * memory_present(). In this for loop, we need check which sections
> - * failed to allocate memmap or usemap, then clear its
> - * ->section_mem_map accordingly. During this process, we need
> - * increase 'nr_consumed_maps' whether its allocation of memmap
> - * or usemap failed or not, so that after we handle the i-th
> - * memory section, can get memmap and usemap of (i+1)-th section
> - * correctly. */
> - for_each_present_section_nr(0, pnum) {
> - struct mem_section *ms;
> -
> - if (nr_consumed_maps >= nr_present_sections) {
> - pr_err("nr_consumed_maps goes beyond nr_present_sections\n");
> - break;
> - }
> - ms = __nr_to_section(pnum);
> - usemap = usemap_map[nr_consumed_maps];
> - if (!usemap) {
> - ms->section_mem_map = 0;
> - nr_consumed_maps++;
> - continue;
> - }
> -
> - map = map_map[nr_consumed_maps];
> - if (!map) {
> - ms->section_mem_map = 0;
> - nr_consumed_maps++;
> + if (nid == nid_begin) {
> + map_count++;
> continue;
> }
> -
> - sparse_init_one_section(__nr_to_section(pnum), pnum, map,
> - usemap);
> - nr_consumed_maps++;
> + sparse_init_nid(nid, pnum_begin, pnum_end, map_count);
~~~
Here, node id passed to sparse_init_nid() should be 'nid_begin', but not
'nid'. When you found out the current section's 'nid' is diferent than
'nid_begin', handle node 'nid_begin', then start to next node 'nid'.


> + nid_begin = nid;
> + pnum_begin = pnum_end;
> + map_count = 1;
> }
> -
> + sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
> vmemmap_populate_print_last();
> -
> - memblock_free_early(__pa(map_map), size2);
> - memblock_free_early(__pa(usemap_map), size);
> }
>
> #ifdef CONFIG_MEMORY_HOTPLUG
> --
> 2.18.0
>