mm: kvfree the swap cluster info if the swap file is unsatisfactory

If initializing a small swap file fails because the swap file has a
problem (holes, etc.) then we need to free the cluster info as part of
cleanup.  Unfortunately a previous patch changed the code to use kvzalloc
but did not change all the vfree calls to use kvfree.

Found by running generic/357 from xfstests.

Link: http://lkml.kernel.org/r/20170831233515.GR3775@magnolia
Fixes: 54f180d3 ("mm, swap: use kvzalloc to allocate some swap data structures")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>	[4.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/swapfile.c

@@ -3290,7 +3290,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	p->flags = 0;
 	spin_unlock(&swap_lock);
 	vfree(swap_map);
-	vfree(cluster_info);
+	kvfree(cluster_info);
 	if (swap_file) {
 		if (inode && S_ISREG(inode->i_mode)) {
 			inode_unlock(inode);