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SubjectRe: [PATCH 1/7] mm/sparse.c: Introduce new function fill_subsection_map()
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On 09.02.20 11:48, Baoquan He wrote:
> Wrap the codes filling subsection map in section_activate() into
> fill_subsection_map(), this makes section_activate() cleaner and
> easier to follow.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> mm/sparse.c | 45 ++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 34 insertions(+), 11 deletions(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index c184b69460b7..9ad741ccbeb6 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -788,24 +788,28 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> depopulate_section_memmap(pfn, nr_pages, altmap);
> }
>
> -static struct page * __meminit section_activate(int nid, unsigned long pfn,
> - unsigned long nr_pages, struct vmem_altmap *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)
> {
> - DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
> struct mem_section *ms = __pfn_to_section(pfn);
> - struct mem_section_usage *usage = NULL;
> + DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
> unsigned long *subsection_map;
> - struct page *memmap;
> int rc = 0;
>
> subsection_mask_set(map, pfn, nr_pages);
>
> - if (!ms->usage) {
> - usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
> - if (!usage)
> - return ERR_PTR(-ENOMEM);
> - ms->usage = usage;
> - }
> subsection_map = &ms->usage->subsection_map[0];
>
> if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
> @@ -816,6 +820,25 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn,
> 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)
> +{
> + struct mem_section *ms = __pfn_to_section(pfn);
> + struct mem_section_usage *usage = NULL;
> + struct page *memmap;
> + int rc = 0;
> +
> + if (!ms->usage) {
> + usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
> + if (!usage)
> + return ERR_PTR(-ENOMEM);
> + ms->usage = usage;
> + }
> +
> + rc = fill_subsection_map(pfn, nr_pages);
> if (rc) {
> if (usage)
> ms->usage = NULL;
>

What about having two variants of
section_activate()/section_deactivate() instead? Then we don't have any
subsection related stuff in !subsection code.

--
Thanks,

David / dhildenb

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