io_uring: use kvfree() in io_sqe_buffer_register()

to #28736503

commit a8c73c1a614f6da6c0b04c393f87447e28cb6de4 upstream

Use kvfree() to free the pages and vmas, since they are allocated by
kvmalloc_array() in a loop.

Fixes: d4ef647510b1 ("io_uring: avoid page allocation warnings")
Signed-off-by: NDenis Efremov <efremov@linux.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200605093203.40087-1-efremov@linux.comSigned-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

fs/io_uring.c

@@ -7073,8 +7073,8 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
 
 		ret = 0;
 		if (!pages || nr_pages > got_pages) {
-			kfree(vmas);
-			kfree(pages);
+			kvfree(vmas);
+			kvfree(pages);
 			pages = kvmalloc_array(nr_pages, sizeof(struct page *),
 						GFP_KERNEL);
 			vmas = kvmalloc_array(nr_pages,