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SubjectRe: [PATCH 3/7] mm/sparse.c: only use subsection map in VMEMMAP case
On Sun, Feb 09, 2020 at 06:48:22PM +0800, 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>

The change looks good to me.

Reviewed-by: Wei Yang <richardw.yang@linux.intel.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)
> {
>--
>2.17.2

--
Wei Yang
Help you, Help me

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