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Subject[PATCH v2 1/2] mm/memory_hotplug.c: check start_pfn in test_pages_in_a_zone()
Date
test_pages_in_a_zone() does not check 'start_pfn' when it is
aligned by section since 'sec_end_pfn' is set equal to 'pfn'.
Since this function is called for testing the range of a sysfs
memory file, 'start_pfn' is always aligned by section.

Fix it by properly setting 'sec_end_pfn' to the next section pfn.

Also make sure that this function returns 1 only when the range
belongs to a zone.

Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrew Banman <abanman@sgi.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> # v4.4+
---
mm/memory_hotplug.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 3e3db7a..c845c5f 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1489,7 +1489,7 @@ bool is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
}

/*
- * Confirm all pages in a range [start, end) is belongs to the same zone.
+ * Confirm all pages in a range [start, end) belong to the same zone.
*/
int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
{
@@ -1497,9 +1497,9 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
struct zone *zone = NULL;
struct page *page;
int i;
- for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn);
+ for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
pfn < end_pfn;
- pfn = sec_end_pfn + 1, sec_end_pfn += PAGES_PER_SECTION) {
+ pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
/* Make sure the memory section is present first */
if (!present_section_nr(pfn_to_section_nr(pfn)))
continue;
@@ -1518,7 +1518,11 @@ int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
zone = page_zone(page);
}
}
- return 1;
+
+ if (zone)
+ return 1;
+ else
+ return 0;
}

/*
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