Re: [PATCH v2 3/7] mm/sparse.c: introduce a new function clear_subsection_map()

Wei Yang
2020-02-20T06:15:20Z

On Thu, Feb 20, 2020 at 12:33:12PM +0800, Baoquan He wrote:
>Wrap the codes which clear subsection map of one memory region from
>section_deactivate() into clear_subsection_map().
>
>Signed-off-by: Baoquan He <bhe@redhat.com>

Reviewed-by: Wei Yang <richardw.yang@linux.intel.com>

>---
> mm/sparse.c | 46 ++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 38 insertions(+), 8 deletions(-)
>
>diff --git a/mm/sparse.c b/mm/sparse.c
>index 977b47acd38d..df857ee9330c 100644
>--- a/mm/sparse.c
>+++ b/mm/sparse.c
>@@ -726,14 +726,25 @@ 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)
>+/**
>+ * 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);
>- bool section_is_early = early_section(ms);
>- struct page *memmap = NULL;
> unsigned long *subsection_map = ms->usage
> ? &ms->usage->subsection_map[0] : NULL;
>
>@@ -744,8 +755,28 @@ 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;
>+ 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)
>+{
>+ struct mem_section *ms = __pfn_to_section(pfn);
>+ bool section_is_early = early_section(ms);
>+ struct page *memmap = NULL;
>+ int rc;
>+
>+
>+ rc = clear_subsection_map(pfn, nr_pages);
>+ if (IS_ERR_VALUE((unsigned long)rc))
>+ return;
> /*
> * There are 3 cases to handle across two configurations
> * (SPARSEMEM_VMEMMAP={y,n}):
>@@ -763,8 +794,7 @@ 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);
>- if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION)) {
>+ if (!rc) {
> unsigned long section_nr = pfn_to_section_nr(pfn);
>
> /*
>@@ -786,7 +816,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
> else
> depopulate_section_memmap(pfn, nr_pages, altmap);
>
>- if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION))
>+ if (!rc)
> ms->section_mem_map = (unsigned long)NULL;
> }
>
>--
>2.17.2

--
Wei Yang
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