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[79.46.200.222]) by smtp.gmail.com with ESMTPSA id q10-20020a1cf30a000000b003b47575d304sm1233345wmq.32.2022.09.28.01.28.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Sep 2022 01:28:26 -0700 (PDT) Date: Wed, 28 Sep 2022 10:28:23 +0200 From: Stefano Garzarella To: Junichi Uekawa Cc: Stefan Hajnoczi , Jason Wang , Eric Dumazet , davem@davemloft.net, netdev@vger.kernel.org, Jakub Kicinski , virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, mst@redhat.com, Paolo Abeni , linux-kernel@vger.kernel.org, Bobby Eshleman Subject: Re: [PATCH] vhost/vsock: Use kvmalloc/kvfree for larger packets. Message-ID: <20220928082823.wyxplop5wtpuurwo@sgarzare-redhat> References: <20220928064538.667678-1-uekawa@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20220928064538.667678-1-uekawa@chromium.org> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Sep 28, 2022 at 03:45:38PM +0900, Junichi Uekawa wrote: >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: > [] dump_stack+0x97/0xdb > [] warn_alloc_failed+0x10f/0x138 > [] ? __alloc_pages_direct_compact+0x38/0xc8 > [] __alloc_pages_nodemask+0x84c/0x90d > [] alloc_kmem_pages+0x17/0x19 > [] kmalloc_order_trace+0x2b/0xdb > [] __kmalloc+0x177/0x1f7 > [] ? copy_from_iter+0x8d/0x31d > [] vhost_vsock_handle_tx_kick+0x1fa/0x301 [vhost_vsock] > [] vhost_worker+0xf7/0x157 [vhost] > [] kthread+0xfd/0x105 > [] ? vhost_dev_set_owner+0x22e/0x22e [vhost] > [] ? flush_kthread_worker+0xf3/0xf3 > [] ret_from_fork+0x4e/0x80 > [] ? flush_kthread_worker+0xf3/0xf3 > >Work around by doing kvmalloc instead. > >Signed-off-by: Junichi Uekawa >--- > > 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); virtio_transport_free_pkt() is used also in virtio_transport.c and vsock_loopback.c where pkt->buf is allocated with kmalloc(), but IIUC kvfree() can be used with that memory, so this should be fine. > kfree(pkt); > } > EXPORT_SYMBOL_GPL(virtio_transport_free_pkt); >-- >2.37.3.998.g577e59143f-goog > This issue should go away with the Bobby's work about introducing sk_buff [1], but we can queue this for now. I'm not sure if we should do the same also in the virtio-vsock driver (virtio_transport.c). Here in vhost-vsock the buf allocated is only used in the host, while in the virtio-vsock driver the buffer is exposed to the device emulated in the host, so it should be physically contiguous (if not, maybe we need to adjust virtio_vsock_rx_fill()). So for now I think is fine to use kvmalloc only on vhost-vsock (eventually we can use it also in vsock_loopback), since the Bobby's patch should rework this code: Reviewed-by: Stefano Garzarella [1] https://lore.kernel.org/lkml/65d117ddc530d12a6d47fcc45b38891465a90d9f.1660362668.git.bobby.eshleman@bytedance.com/ Thanks, Stefano