4.18-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 51896864579d5a3349740847083f4db5c6487164 ]
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.
Link: http://lkml.kernel.org/r/20180921095015.26088-1-yuehaibing@huawei.com Fixes: 09e35a4a1ca8 ("mm/gup_benchmark: handle gup failures") Signed-off-by: YueHaibing yuehaibing@huawei.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: Michael S. Tsirkin mst@redhat.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 6a473709e9b6..7405c9d89d65 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;