[PATCH 1/1] mm/vmalloc: fix align value calculation error

[zijun_hu]

it causes double align requirement for __get_vm_area_node() if parameter
size is power of 2 and VM_IOREMAP is set in parameter flags

get_order_long() is implemented and used instead of fls_long() for
fixing the bug

Signed-off-by: zijun_hu <zijun_hu@xxxxxxx>
---
 include/linux/bitops.h | 17 +++++++++++++++++
 mm/vmalloc.c           |  2 +-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 299e76b..c18448d 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -192,6 +192,23 @@ static inline unsigned fls_long(unsigned long l)
 }
 
 /**
+ * get_order_long - get order after rounding @l up to power of 2
+ * @l: parameter
+ *
+ * it is same as get_count_order() but long type parameter
+ * or 0 is returned if @l == 0UL
+ */
+static inline int get_order_long(unsigned long l)
+{
+	if (l == 0UL)
+		return 0;
+	else if (l & (l - 1UL))
+		return fls_long(l);
+	else
+		return fls_long(l) - 1;
+}
+
+/**
  * __ffs64 - find first set bit in a 64 bit word
  * @word: The 64 bit word
  *
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 91f44e7..7d717f3 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1360,7 +1360,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
 
 	BUG_ON(in_interrupt());
 	if (flags & VM_IOREMAP)
-		align = 1ul << clamp_t(int, fls_long(size),
+		align = 1ul << clamp_t(int, get_order_long(size),
 				       PAGE_SHIFT, IOREMAP_MAX_ORDER);
 
 	size = PAGE_ALIGN(size);
-- 
1.9.1