Re: [PATCH 0/5] vsock/virtio: SKB allocation improvements

Stefano Garzarella
2025-06-27T10:51:56Z

On Wed, Jun 25, 2025 at 02:15:38PM +0100, Will Deacon wrote:
>Hi folks,
>
>We're using vsock extensively in Android as a channel over which we can
>route binder transactions to/from virtual machines managed by the
>Android Virtualisation Framework. However, we have been observing some
>issues in production builds when using vsock in a low-memory environment
>(on the host and the guest) such as:
>
> * The host receive path hanging forever, despite the guest performing
> a successful write to the socket.
>
> * Page allocation failures in the vhost receive path (this is a likely
> contributor to the above)
>
> * -ENOMEM coming back from sendmsg()
>
>This series aims to improve the vsock SKB allocation for both the host
>(vhost) and the guest when using the virtio transport to help mitigate
>these issues. Specifically:
>
> - Avoid single allocations of order > PAGE_ALLOC_COSTLY_ORDER
>
> - Use non-linear SKBs for the transmit and vhost receive paths
>
> - Reduce the guest RX buffers to a single page
>
>There are more details in the individual commit messages but overall
>this results in less wasted memory and puts less pressure on the
>allocator.
>
>This is my first time looking at this stuff, so all feedback is welcome.

Thank you very much for this series!

I left some minor comments, but overall LGTM!

Thanks,
Stefano

>
>Patches based on v6.16-rc3.
>
>Cheers,
>
>Will
>
>Cc: Keir Fraser <keirf@google.com>
>Cc: Steven Moreland <smoreland@google.com>
>Cc: Frederick Mayle <fmayle@google.com>
>Cc: Stefan Hajnoczi <stefanha@redhat.com>
>Cc: Stefano Garzarella <sgarzare@redhat.com>
>Cc: "Michael S. Tsirkin" <mst@redhat.com>
>Cc: Jason Wang <jasowang@redhat.com>
>Cc: "Eugenio Pérez" <eperezma@redhat.com>
>Cc: netdev@vger.kernel.org
>Cc: virtualization@lists.linux.dev
>
>--->8
>
>Will Deacon (5):
> vhost/vsock: Avoid allocating arbitrarily-sized SKBs
> vsock/virtio: Resize receive buffers so that each SKB fits in a page
> vhost/vsock: Allocate nonlinear SKBs for handling large receive
> buffers
> vsock/virtio: Rename virtio_vsock_skb_rx_put() to
> virtio_vsock_skb_put()
> vhost/vsock: Allocate nonlinear SKBs for handling large transmit
> buffers
>
> drivers/vhost/vsock.c | 21 +++++++++------
> include/linux/virtio_vsock.h | 36 +++++++++++++++++++------
> net/vmw_vsock/virtio_transport.c | 2 +-
> net/vmw_vsock/virtio_transport_common.c | 9 +++++--
> 4 files changed, 49 insertions(+), 19 deletions(-)
>
>--
>2.50.0.714.g196bf9f422-goog
>
>