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-rw-r--r--mm/memory_hotplug.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c8f0a8c2d049..8e0fa209d533 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -605,7 +605,18 @@ static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages)
* this and the first chunk to online will be pageblock_nr_pages.
*/
for (pfn = start_pfn; pfn < end_pfn;) {
- int order = min_t(int, MAX_ORDER, __ffs(pfn));
+ int order;
+
+ /*
+ * Free to online pages in the largest chunks alignment allows.
+ *
+ * __ffs() behaviour is undefined for 0. start == 0 is
+ * MAX_ORDER-aligned, Set order to MAX_ORDER for the case.
+ */
+ if (pfn)
+ order = min_t(int, MAX_ORDER, __ffs(pfn));
+ else
+ order = MAX_ORDER;
(*online_page_callback)(pfn_to_page(pfn), order);
pfn += (1UL << order);