From: Herbert Xu Date: Mon, 25 Jan 2010 23:51:01 +0000 (-0800) Subject: virtio_net: Make delayed refill more reliable X-Git-Tag: firefly_0821_release~10186^2~1533 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=be4aa3f7edac32e5bc445bb108e79a7f5c3d7b1f;p=firefly-linux-kernel-4.4.55.git virtio_net: Make delayed refill more reliable commit 39d321577405e8e269fd238b278aaf2425fa788a upstream. I have seen RX stalls on a machine that experienced a suspected OOM. After the stall, the RX buffer is empty on the guest side and there are exactly 16 entries available on the host side. As the number of entries is less than that required by a maximal skb, the host cannot proceed. The guest did not have a refill job scheduled. My diagnosis is that an OOM had occured, with the delayed refill job scheduled. The job was able to allocate at least one skb, but not enough to overcome the minimum required by the host to proceed. As the refill job would only reschedule itself if it failed completely to allocate any skbs, this would lead to an RX stall. The following patch removes this stall possibility by always rescheduling the refill job until the ring is totally refilled. Testing has shown that the RX stall no longer occurs whereas previously it would occur within a day. Signed-off-by: Herbert Xu Acked-by: Rusty Russell Signed-off-by: David S. Miller Cc: Bruce Rogers Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index b9e002fccbca..7e3788d54310 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -398,8 +398,7 @@ static void refill_work(struct work_struct *work) vi = container_of(work, struct virtnet_info, refill.work); napi_disable(&vi->napi); - try_fill_recv(vi, GFP_KERNEL); - still_empty = (vi->num == 0); + still_empty = !try_fill_recv(vi, GFP_KERNEL); napi_enable(&vi->napi); /* In theory, this can happen: if we don't get any buffers in