nvmet-rdma: use kvcalloc for commands and responses arrays

Replace kcalloc with kvcalloc for allocation of the commands and
responses arrays. Each command structure is 272 bytes and each
response structure is 672 bytes. These arrays typically exceed a
single page, and grow much larger with high queue depths
(e.g., commands >2MB, responses >170KB)

kvcalloc automatically falls back to vmalloc for large or fragmented
allocations, improving reliability. In our case, this memory is not
aimed for DMA operations and could be safely allocated by kvcalloc.
Using virtually contiguous memory helps to avoid allocation failures
and out-of-memory conditions common with kcalloc on large pools.

Signed-off-by: Israel Rukshin <[e-mail]>
Reviewed-by: Max Gurtovoy <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Keith Busch <[e-mail]>

drivers/nvme/target/rdma.c

···
 	struct nvmet_rdma_cmd *cmds;
 	int ret = -EINVAL, i;
 
-	cmds = kcalloc(nr_cmds, sizeof(struct nvmet_rdma_cmd), GFP_KERNEL);
+	cmds = kvcalloc(nr_cmds, sizeof(struct nvmet_rdma_cmd), GFP_KERNEL);
 	if (!cmds)
 		goto out;
 
···
 out_free:
 	while (--i >= 0)
 		nvmet_rdma_free_cmd(ndev, cmds + i, admin);
-	kfree(cmds);
+	kvfree(cmds);
 out:
 	return ERR_PTR(ret);
 }
···
 
 	for (i = 0; i < nr_cmds; i++)
 		nvmet_rdma_free_cmd(ndev, cmds + i, admin);
-	kfree(cmds);
+	kvfree(cmds);
 }
 
 static int nvmet_rdma_alloc_rsp(struct nvmet_rdma_device *ndev,
···
 			NUMA_NO_NODE, false, true))
 		goto out;
 
-	queue->rsps = kcalloc(nr_rsps, sizeof(struct nvmet_rdma_rsp),
+	queue->rsps = kvcalloc(nr_rsps, sizeof(struct nvmet_rdma_rsp),
 			GFP_KERNEL);
 	if (!queue->rsps)
 		goto out_free_sbitmap;
···
 out_free:
 	while (--i >= 0)
 		nvmet_rdma_free_rsp(ndev, &queue->rsps[i]);
-	kfree(queue->rsps);
+	kvfree(queue->rsps);
 out_free_sbitmap:
 	sbitmap_free(&queue->rsp_tags);
 out:
···
 
 	for (i = 0; i < nr_rsps; i++)
 		nvmet_rdma_free_rsp(ndev, &queue->rsps[i]);
-	kfree(queue->rsps);
+	kvfree(queue->rsps);
 	sbitmap_free(&queue->rsp_tags);
 }