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SubjectRe: [PATCH v3 3/7] mm/sparse.c: introduce a new function clear_subsection_map()
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On 07.03.20 09:42, Baoquan He wrote:
> Factor out the code which clear subsection map of one memory region from
> section_deactivate() into clear_subsection_map().
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> mm/sparse.c | 31 ++++++++++++++++++++++++-------
> 1 file changed, 24 insertions(+), 7 deletions(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index e37c0abcdc89..d9dcd58d5c1d 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -726,15 +726,11 @@ static void free_map_bootmem(struct page *memmap)
> }
> #endif /* CONFIG_SPARSEMEM_VMEMMAP */
>
> -static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> - struct vmem_altmap *altmap)
> +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);
> - bool section_is_early = early_section(ms);
> - struct page *memmap = NULL;
> - bool empty = false;
> unsigned long *subsection_map = ms->usage
> ? &ms->usage->subsection_map[0] : NULL;
>
> @@ -745,8 +741,31 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> 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);
> +

Nit: I'd drop this line.

> + return 0;
> +}
> +
> +static bool is_subsection_map_empty(struct mem_section *ms)
> +{
> + return bitmap_empty(&ms->usage->subsection_map[0],
> + SUBSECTIONS_PER_SECTION);
> +}
> +
> +static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> + struct vmem_altmap *altmap)
> +{
> + struct mem_section *ms = __pfn_to_section(pfn);
> + bool section_is_early = early_section(ms);
> + struct page *memmap = NULL;
> + bool empty = false;

Nit: No need to initialize empty.

> +
> + if (clear_subsection_map(pfn, nr_pages))
> return;
>

Nit: I'd drop this empty line.

> + empty = is_subsection_map_empty(ms);
> /*
> * There are 3 cases to handle across two configurations
> * (SPARSEMEM_VMEMMAP={y,n}):
> @@ -764,8 +783,6 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> *
> * For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified
> */
> - bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
> - empty = bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION);

I do wonder why you moved this up the comment?

> if (empty) {
> unsigned long section_nr = pfn_to_section_nr(pfn);
>
>

Reviewed-by: David Hildenbrand <david@redhat.com>

--
Thanks,

David / dhildenb

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