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SubjectRe: [PATCH 3/7] mm/sparse.c: only use subsection map in VMEMMAP case
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On 09.02.20 11:48, Baoquan He wrote:
> Currently, subsection map is used when SPARSEMEM is enabled, including
> VMEMMAP case and !VMEMMAP case. However, subsection hotplug is not
> supported at all in SPARSEMEM|!VMEMMAP case, subsection map is unnecessary
> and misleading. Let's adjust code to only allow subsection map being
> used in SPARSEMEM|VMEMMAP case.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> include/linux/mmzone.h | 2 +
> mm/sparse.c | 231 ++++++++++++++++++++++-------------------
> 2 files changed, 124 insertions(+), 109 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 462f6873905a..fc0de3a9a51e 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -1185,7 +1185,9 @@ static inline unsigned long section_nr_to_pfn(unsigned long sec)
> #define SUBSECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SUBSECTION_MASK)
>
> struct mem_section_usage {
> +#ifdef CONFIG_SPARSEMEM_VMEMMAP
> DECLARE_BITMAP(subsection_map, SUBSECTIONS_PER_SECTION);
> +#endif
> /* See declaration of similar field in struct zone */
> unsigned long pageblock_flags[0];
> };
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 696f6b9f706e..cf55d272d0a9 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -209,41 +209,6 @@ static inline unsigned long first_present_section_nr(void)
> return next_present_section_nr(-1);
> }
>
> -static void subsection_mask_set(unsigned long *map, unsigned long pfn,
> - unsigned long nr_pages)
> -{
> - int idx = subsection_map_index(pfn);
> - int end = subsection_map_index(pfn + nr_pages - 1);
> -
> - bitmap_set(map, idx, end - idx + 1);
> -}
> -
> -void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
> -{
> - int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
> - unsigned long nr, start_sec = pfn_to_section_nr(pfn);
> -
> - if (!nr_pages)
> - return;
> -
> - for (nr = start_sec; nr <= end_sec; nr++) {
> - struct mem_section *ms;
> - unsigned long pfns;
> -
> - pfns = min(nr_pages, PAGES_PER_SECTION
> - - (pfn & ~PAGE_SECTION_MASK));
> - ms = __nr_to_section(nr);
> - subsection_mask_set(ms->usage->subsection_map, pfn, pfns);
> -
> - pr_debug("%s: sec: %lu pfns: %lu set(%d, %d)\n", __func__, nr,
> - pfns, subsection_map_index(pfn),
> - subsection_map_index(pfn + pfns - 1));
> -
> - pfn += pfns;
> - nr_pages -= pfns;
> - }
> -}
> -
> /* Record a memory area against a node. */
> void __init memory_present(int nid, unsigned long start, unsigned long end)
> {
> @@ -432,12 +397,134 @@ static unsigned long __init section_map_size(void)
> return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
> }
>
> +static void subsection_mask_set(unsigned long *map, unsigned long pfn,
> + unsigned long nr_pages)
> +{
> + int idx = subsection_map_index(pfn);
> + int end = subsection_map_index(pfn + nr_pages - 1);
> +
> + bitmap_set(map, idx, end - idx + 1);
> +}
> +
> +void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
> +{
> + int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
> + unsigned long nr, start_sec = pfn_to_section_nr(pfn);
> +
> + if (!nr_pages)
> + return;
> +
> + for (nr = start_sec; nr <= end_sec; nr++) {
> + struct mem_section *ms;
> + unsigned long pfns;
> +
> + pfns = min(nr_pages, PAGES_PER_SECTION
> + - (pfn & ~PAGE_SECTION_MASK));
> + ms = __nr_to_section(nr);
> + subsection_mask_set(ms->usage->subsection_map, pfn, pfns);
> +
> + pr_debug("%s: sec: %lu pfns: %lu set(%d, %d)\n", __func__, nr,
> + pfns, subsection_map_index(pfn),
> + subsection_map_index(pfn + pfns - 1));
> +
> + pfn += pfns;
> + nr_pages -= pfns;
> + }
> +}
> +
> +/**
> + * clear_subsection_map - Clear subsection map of one memory region
> + *
> + * @pfn - start pfn of the memory range
> + * @nr_pages - number of pfns to add in the region
> + *
> + * This is only intended for hotplug, and clear the related subsection
> + * map inside one section.
> + *
> + * Return:
> + * * -EINVAL - Section already deactived.
> + * * 0 - Subsection map is emptied.
> + * * 1 - Subsection map is not empty.
> + */
> +static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
> +{
> + DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
> + DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
> + struct mem_section *ms = __pfn_to_section(pfn);
> + unsigned long *subsection_map = ms->usage
> + ? &ms->usage->subsection_map[0] : NULL;
> +
> + subsection_mask_set(map, pfn, nr_pages);
> + if (subsection_map)
> + bitmap_and(tmp, map, subsection_map, SUBSECTIONS_PER_SECTION);
> +
> + if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
> + "section already deactivated (%#lx + %ld)\n",
> + pfn, nr_pages))
> + return -EINVAL;
> +
> + bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
> +
> + if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION))
> + return 0;
> +
> + return 1;
> +}
> +
> +/**
> + * fill_subsection_map - fill subsection map of a memory region
> + * @pfn - start pfn of the memory range
> + * @nr_pages - number of pfns to add in the region
> + *
> + * This clears the related subsection map inside one section, and only
> + * intended for hotplug.
> + *
> + * Return:
> + * * 0 - On success.
> + * * -EINVAL - Invalid memory region.
> + * * -EEXIST - Subsection map has been set.
> + */
> +static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
> +{
> + struct mem_section *ms = __pfn_to_section(pfn);
> + DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
> + unsigned long *subsection_map;
> + int rc = 0;
> +
> + subsection_mask_set(map, pfn, nr_pages);
> +
> + subsection_map = &ms->usage->subsection_map[0];
> +
> + if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
> + rc = -EINVAL;
> + else if (bitmap_intersects(map, subsection_map, SUBSECTIONS_PER_SECTION))
> + rc = -EEXIST;
> + else
> + bitmap_or(subsection_map, map, subsection_map,
> + SUBSECTIONS_PER_SECTION);
> +
> + return rc;
> +}
> +
> #else
> static unsigned long __init section_map_size(void)
> {
> return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
> }
>
> +void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
> +{
> +}
> +
> +static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
> +{
> + return 0;
> +}
> +static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
> +{
> + return 0;
> +}
> +
> struct page __init *__populate_section_memmap(unsigned long pfn,
> unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
> {
> @@ -726,45 +813,6 @@ static void free_map_bootmem(struct page *memmap)
> }
> #endif /* CONFIG_SPARSEMEM_VMEMMAP */
>
> -/**
> - * clear_subsection_map - Clear subsection map of one memory region
> - *
> - * @pfn - start pfn of the memory range
> - * @nr_pages - number of pfns to add in the region
> - *
> - * This is only intended for hotplug, and clear the related subsection
> - * map inside one section.
> - *
> - * Return:
> - * * -EINVAL - Section already deactived.
> - * * 0 - Subsection map is emptied.
> - * * 1 - Subsection map is not empty.
> - */
> -static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
> -{
> - DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
> - DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
> - struct mem_section *ms = __pfn_to_section(pfn);
> - unsigned long *subsection_map = ms->usage
> - ? &ms->usage->subsection_map[0] : NULL;
> -
> - subsection_mask_set(map, pfn, nr_pages);
> - if (subsection_map)
> - bitmap_and(tmp, map, subsection_map, SUBSECTIONS_PER_SECTION);
> -
> - if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
> - "section already deactivated (%#lx + %ld)\n",
> - pfn, nr_pages))
> - return -EINVAL;
> -
> - bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
> -
> - if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION))
> - return 0;
> -
> - return 1;
> -}
> -
> static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> struct vmem_altmap *altmap)
> {
> @@ -818,41 +866,6 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> depopulate_section_memmap(pfn, nr_pages, altmap);
> }
>
> -/**
> - * fill_subsection_map - fill subsection map of a memory region
> - * @pfn - start pfn of the memory range
> - * @nr_pages - number of pfns to add in the region
> - *
> - * This clears the related subsection map inside one section, and only
> - * intended for hotplug.
> - *
> - * Return:
> - * * 0 - On success.
> - * * -EINVAL - Invalid memory region.
> - * * -EEXIST - Subsection map has been set.
> - */
> -static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
> -{
> - struct mem_section *ms = __pfn_to_section(pfn);
> - DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
> - unsigned long *subsection_map;
> - int rc = 0;
> -
> - subsection_mask_set(map, pfn, nr_pages);
> -
> - subsection_map = &ms->usage->subsection_map[0];
> -
> - if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
> - rc = -EINVAL;
> - else if (bitmap_intersects(map, subsection_map, SUBSECTIONS_PER_SECTION))
> - rc = -EEXIST;
> - else
> - bitmap_or(subsection_map, map, subsection_map,
> - SUBSECTIONS_PER_SECTION);
> -
> - return rc;
> -}
> -
> static struct page * __meminit section_activate(int nid, unsigned long pfn,
> unsigned long nr_pages, struct vmem_altmap *altmap)
> {
>

I'd prefer adding more ifdefs to avoid heavy code movement. Would make
it much easier to review :)

--
Thanks,

David / dhildenb

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