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

From: Pavel Tatashin
Date: Sun Jul 01 2018 - 21:45:27 EST


On Sun, Jul 1, 2018 at 9:34 PM Baoquan He <bhe@xxxxxxxxxx> wrote:
>
> Hi Pavel,
>
> 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.
>
> > @@ -617,87 +491,24 @@ void __init sparse_init_nid(int nid, unsigned long pnum_begin,
> > */
> > 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();
>
> Not very sure if removing set_pageblock_order() calling here is OK. What
> if CONFIG_HUGETLB_PAGE_SIZE_VARIABLE is enabled? usemap_size() depends
> on value of 'pageblock_order'.

Hi Baoquan,

Nice catch, you are right, I incorrectly removed this call, will add
it back in the next version.

Pavel

>
> Thanks
> Baoquan
>
> > + 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);
> > + 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
> >
>