linux-kernel - [PATCH -next] mm/gup_benchmark: Fix unsigned comparison to zero in __gup_benchmark

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Message-ID: <20180921095015.26088-1-yuehaibing@huawei.com>
Date:   Fri, 21 Sep 2018 17:50:15 +0800
From:   YueHaibing <yuehaibing@...wei.com>
To:     <akpm@...ux-foundation.org>, <mst@...hat.com>,
        <keescook@...omium.org>, <kirill.shutemov@...ux.intel.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        YueHaibing <yuehaibing@...wei.com>
Subject: [PATCH -next] mm/gup_benchmark: Fix unsigned comparison to zero in __gup_benchmark_ioctl

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 <yuehaibing@...wei.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