mm/cma_debug.c: fix the break condition in cma_maxchunk_get()

[ Upstream commit f0fd50504a54f5548eb666dc16ddf8394e44e4b7 ]

If not find zero bit in find_next_zero_bit(), it will return the size
parameter passed in, so the start bit should be compared with bitmap_maxno
rather than cma->count.  Although getting maxchunk is working fine due to
zero value of order_per_bit currently, the operation will be stuck if
order_per_bit is set as non-zero.

Link: http://lkml.kernel.org/r/20190319092734.276-1-zbestahu@gmail.com
Signed-off-by: Yue Hu <huyue2@yulong.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Joe Perches <joe@perches.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Safonov <d.safonov@partner.samsung.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/mm/cma_debug.c b/mm/cma_debug.c
index f8e4b60..da50dab 100644 (file)
--- a/mm/cma_debug.c
+++ b/mm/cma_debug.c
@@ -57,7 +57,7 @@ static int cma_maxchunk_get(void *data, u64 *val)
        mutex_lock(&cma->lock);
        for (;;) {
                start = find_next_zero_bit(cma->bitmap, bitmap_maxno, end);
-               if (start >= cma->count)
+               if (start >= bitmap_maxno)
                        break;
                end = find_next_bit(cma->bitmap, bitmap_maxno, start);
                maxchunk = max(end - start, maxchunk);