linux-kernel - [PATCH] vhost/vsock: Use kvmalloc/kvfree for larger packets.

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Message-Id: <20220928064538.667678-1-uekawa@chromium.org>
Date:   Wed, 28 Sep 2022 15:45:38 +0900
From:   Junichi Uekawa <uekawa@...omium.org>
To:     Stefan Hajnoczi <stefanha@...hat.com>,
        Stefano Garzarella <sgarzare@...hat.com>
Cc:     Jason Wang <jasowang@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>, davem@...emloft.net,
        netdev@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        mst@...hat.com, Paolo Abeni <pabeni@...hat.com>,
        linux-kernel@...r.kernel.org, Junichi Uekawa <uekawa@...omium.org>
Subject: [PATCH] vhost/vsock: Use kvmalloc/kvfree for larger packets.

When copying a large file over sftp over vsock, data size is usually 32kB,
and kmalloc seems to fail to try to allocate 32 32kB regions.

 Call Trace:
  [<ffffffffb6a0df64>] dump_stack+0x97/0xdb
  [<ffffffffb68d6aed>] warn_alloc_failed+0x10f/0x138
  [<ffffffffb68d868a>] ? __alloc_pages_direct_compact+0x38/0xc8
  [<ffffffffb664619f>] __alloc_pages_nodemask+0x84c/0x90d
  [<ffffffffb6646e56>] alloc_kmem_pages+0x17/0x19
  [<ffffffffb6653a26>] kmalloc_order_trace+0x2b/0xdb
  [<ffffffffb66682f3>] __kmalloc+0x177/0x1f7
  [<ffffffffb66e0d94>] ? copy_from_iter+0x8d/0x31d
  [<ffffffffc0689ab7>] vhost_vsock_handle_tx_kick+0x1fa/0x301 [vhost_vsock]
  [<ffffffffc06828d9>] vhost_worker+0xf7/0x157 [vhost]
  [<ffffffffb683ddce>] kthread+0xfd/0x105
  [<ffffffffc06827e2>] ? vhost_dev_set_owner+0x22e/0x22e [vhost]
  [<ffffffffb683dcd1>] ? flush_kthread_worker+0xf3/0xf3
  [<ffffffffb6eb332e>] ret_from_fork+0x4e/0x80
  [<ffffffffb683dcd1>] ? flush_kthread_worker+0xf3/0xf3

Work around by doing kvmalloc instead.

Signed-off-by: Junichi Uekawa <uekawa@...omium.org>
---

 drivers/vhost/vsock.c                   | 2 +-
 net/vmw_vsock/virtio_transport_common.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 368330417bde..5703775af129 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -393,7 +393,7 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
 		return NULL;
 	}

-	pkt->buf = kmalloc(pkt->len, GFP_KERNEL);
+	pkt->buf = kvmalloc(pkt->len, GFP_KERNEL);
 	if (!pkt->buf) {
 		kfree(pkt);
 		return NULL;
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index ec2c2afbf0d0..3a12aee33e92 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1342,7 +1342,7 @@ EXPORT_SYMBOL_GPL(virtio_transport_recv_pkt);

 void virtio_transport_free_pkt(struct virtio_vsock_pkt *pkt)
 {
-	kfree(pkt->buf);
+	kvfree(pkt->buf);
 	kfree(pkt);
 }
 EXPORT_SYMBOL_GPL(virtio_transport_free_pkt);
-- 
2.37.3.998.g577e59143f-goog