Date:   Sun, 1 Jul 2018 21:44:44 -0400
From:   Pavel Tatashin <pasha.tatashin@...cle.com>
To:     bhe@...hat.com
Cc:     Steven Sistare <steven.sistare@...cle.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kirill.shutemov@...ux.intel.com, Michal Hocko <mhocko@...e.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        dan.j.williams@...el.com, jack@...e.cz, jglisse@...hat.com,
        Souptick Joarder <jrdr.linux@...il.com>,
        gregkh@...uxfoundation.org, Vlastimil Babka <vbabka@...e.cz>,
        Wei Yang <richard.weiyang@...il.com>, dave.hansen@...el.com,
        rientjes@...gle.com, mingo@...nel.org, osalvador@...hadventures.net
Subject: Re: [PATCH v2 2/2] mm/sparse: start using sparse_init_nid(), and
 remove old code

On Sun, Jul 1, 2018 at 9:34 PM Baoquan He <bhe@...hat.com> 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
> >
>

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