[PATCH -next] mm/gup_benchmark: Fix unsigned comparison to zero in __gup_benchmark_ioctl

[YueHaibing]

get_user_pages_fast will return negative value if no pages were pinned,
then be converted to a unsigned, which is compared to zero, giving
the wrong result.

Fixes: 09e35a4a1ca8 ("mm/gup_benchmark: handle gup failures")
Signed-off-by: YueHaibing <yuehaib...@huawei.com>
---
 mm/gup_benchmark.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
index 6a47370..7405c9d8 100644
--- a/mm/gup_benchmark.c
+++ b/mm/gup_benchmark.c
@@ -19,7 +19,8 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
                struct gup_benchmark *gup)
 {
        ktime_t start_time, end_time;
-       unsigned long i, nr, nr_pages, addr, next;
+       unsigned long i, nr_pages, addr, next;
+       int nr;
        struct page **pages;
 
        nr_pages = gup->size / PAGE_SIZE;
-- 
2.7.0