misc: ibmvmc: Use GFP_ATOMIC under spin lock

The function alloc_dma_buffer() is called from ibmvmc_add_buffer(),
in which a spin lock be held here, so we should use GFP_ATOMIC when
a lock is held.

Fixes: 0eca353e7ae7 ("misc: IBM Virtual Management Channel Driver (VMC)")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/ibmvmc.c

@@ -273,7 +273,7 @@ static void *alloc_dma_buffer(struct vio_dev *vdev, size_t size,
 			      dma_addr_t *dma_handle)
 {
 	/* allocate memory */
-	void *buffer = kzalloc(size, GFP_KERNEL);
+	void *buffer = kzalloc(size, GFP_ATOMIC);
 
 	if (!buffer) {
 		*dma_handle = 0;