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

Baoquan He
2020-02-20T04:33:54Z

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>
---
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