percpu: make pcpu_alloc_chunk() use pcpu_mem_free() instead of kfree()

pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
	BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long)

It hardly could be ever bigger than PAGE_SIZE even for large-scale machine,
but for consistency with its couterpart pcpu_mem_zalloc(),
use pcpu_mem_free() instead.

Commit b4916cb ("percpu: make pcpu_free_chunk() use
pcpu_mem_free() instead of kfree()") addressed this problem, but
missed this one.

tj: commit message updated

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 099a19d ("percpu: allow limited allocation before slab is online)
Cc: stable@vger.kernel.org

mm/percpu.c

@@ -610,7 +610,7 @@ static struct pcpu_chunk *pcpu_alloc_chunk(void)
 	chunk->map = pcpu_mem_zalloc(PCPU_DFL_MAP_ALLOC *
 						sizeof(chunk->map[0]));
 	if (!chunk->map) {
-		kfree(chunk);
+		pcpu_mem_free(chunk, pcpu_chunk_struct_size);
 		return NULL;
 	}