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Message-ID: <1682576442.2203932-1-xuanzhuo@linux.alibaba.com>
Subject: Re: [PATCH] virtio_net: suppress cpu stall when free_unused_bufs
Date:   Thu, 27 Apr 2023 14:20:42 +0800
From:   Xuan Zhuo <xuanzhuo@linux.alibaba.com>
To:     Wenliang Wang <wangwenliang.1995@bytedance.com>
Cc:     virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Wenliang Wang <wangwenliang.1995@bytedance.com>,
        mst@redhat.com, jasowang@redhat.com, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com
References: <20230427043433.2594960-1-wangwenliang.1995@bytedance.com>
In-Reply-To: <20230427043433.2594960-1-wangwenliang.1995@bytedance.com>
Precedence: bulk

On Thu, 27 Apr 2023 12:34:33 +0800, Wenliang Wang <wangwenliang.1995@bytedance.com> wrote:
> For multi-queue and large rx-ring-size use case, the following error

Cound you give we one number for example?

> occurred when free_unused_bufs:
> rcu: INFO: rcu_sched self-detected stall on CPU.
>
> Signed-off-by: Wenliang Wang <wangwenliang.1995@bytedance.com>
> ---
>  drivers/net/virtio_net.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index ea1bd4bb326d..21d8382fd2c7 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -3565,6 +3565,7 @@ static void free_unused_bufs(struct virtnet_info *vi)
>  		struct virtqueue *vq = vi->rq[i].vq;
>  		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
>  			virtnet_rq_free_unused_buf(vq, buf);
> +		schedule();

Just for rq?

Do we need to do the same thing for sq?

Thanks.


>  	}
>  }
>
> --
> 2.20.1
>