mm: shrinker: use kvzalloc_node() from expand_one_shrinker_info()

syzbot is reporting uninit-value at shrinker_alloc(), for commit
307bece ("mm: shrinker: add a secondary array for
shrinker_info::{map, nr_deferred}") which assumed that the ->unit was
allocated with __GFP_ZERO forgot to replace kvmalloc_node() in
expand_one_shrinker_info() with kvzalloc_node().

Link: https://lkml.kernel.org/r/9226cc0a-10e0-4489-80c5-58c3b5b4359c@I-love.SAKURA.ne.jp
Reported-by: syzbot <syzbot+1e0ed05798af62917464@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=1e0ed05798af62917464
Fixes: 307bece ("mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred}")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/shrinker.c

@@ -126,7 +126,7 @@ static int expand_one_shrinker_info(struct mem_cgroup *memcg, int new_size,
 		if (new_nr_max <= old->map_nr_max)
 			continue;
 
-		new = kvmalloc_node(sizeof(*new) + new_size, GFP_KERNEL, nid);
+		new = kvzalloc_node(sizeof(*new) + new_size, GFP_KERNEL, nid);
 		if (!new)
 			return -ENOMEM;