diff --git a/include/linux/page_size_compat.h b/include/linux/page_size_compat.h
index 4059902922b7..17450746414a 100644
--- a/include/linux/page_size_compat.h
+++ b/include/linux/page_size_compat.h
@@ -59,4 +59,31 @@ static __always_inline unsigned __page_shift(void)
 
 #define __PAGE_ALIGNED(addr)    (!__offset_in_page_log(addr))
 
+/*
+ * Increases @size by an adequate amount to allow __PAGE_SIZE alignment
+ * by rounding up; given that @size is already a multiple of the
+ * base page size (PAGE_SIZE).
+ *
+ * Example:
+ *     If __PAGE_SHIFT == PAGE_SHIFT == 12
+ *         @size is increased by 0
+ *             ((1 << (0)) - 1) << PAGE_SHIFT
+ *             (1        ) - 1) << PAGE_SHIFT
+ *             (0             ) << PAGE_SHIFT
+ *
+ *     If __PAGE_SHIFT == 13 and PAGE_SHIFT == 12
+ *         @size is increased by PAGE_SIZE (4KB):
+ *             ((1 << (1)) - 1) << PAGE_SHIFT
+ *             (2        ) - 1) << PAGE_SHIFT
+ *             (1             ) << PAGE_SHIFT
+ *     If __PAGE_SHIFT == 14 and PAGE_SHIFT == 12
+ *         @size is increased by 3xPAGE_SIZE (12KB):
+ *             ((1 << (2)) - 1) << PAGE_SHIFT
+ *             (4        ) - 1) << PAGE_SHIFT
+ *             (3             ) << PAGE_SHIFT
+ *     ...
+ */
+#define __PAGE_SIZE_ROUND_UP_ADJ(size) \
+	((size) + (((1 << (__PAGE_SHIFT - PAGE_SHIFT)) - 1) << PAGE_SHIFT))
+
 #endif /* __LINUX_PAGE_SIZE_COMPAT_H */
diff --git a/mm/mmap.c b/mm/mmap.c
index 2f8383c61f5b..bc6948ca5f8b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -17,6 +17,7 @@
 #include <linux/shm.h>
 #include <linux/mman.h>
 #include <linux/pagemap.h>
+#include <linux/page_size_compat.h>
 #include <linux/swap.h>
 #include <linux/syscalls.h>
 #include <linux/capability.h>
@@ -617,7 +618,7 @@ static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
 	VMA_ITERATOR(vmi, current->mm, 0);
 
 	/* Adjust search length to account for worst case alignment overhead */
-	length = info->length + info->align_mask + info->start_gap;
+	length = __PAGE_SIZE_ROUND_UP_ADJ(info->length + info->align_mask + info->start_gap);
 	if (length < info->length)
 		return -ENOMEM;
 
@@ -653,7 +654,7 @@ retry:
 		}
 	}
 
-	return gap;
+	return __PAGE_ALIGN(gap);
 }
 
 /**
@@ -674,7 +675,7 @@ static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 	VMA_ITERATOR(vmi, current->mm, 0);
 
 	/* Adjust search length to account for worst case alignment overhead */
-	length = info->length + info->align_mask + info->start_gap;
+	length = __PAGE_SIZE_ROUND_UP_ADJ(info->length + info->align_mask + info->start_gap);
 	if (length < info->length)
 		return -ENOMEM;
 
@@ -705,7 +706,7 @@ retry:
 		}
 	}
 
-	return gap;
+	return __PAGE_ALIGN(gap);
 }
 
 /*