From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753762AbaCGQX0 (ORCPT ); Fri, 7 Mar 2014 11:23:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59562 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751578AbaCGQXY (ORCPT ); Fri, 7 Mar 2014 11:23:24 -0500 Message-ID: <5319F272.1070101@redhat.com> Date: Fri, 07 Mar 2014 17:23:14 +0100 From: Thomas Graf Organization: Red Hat, Inc. User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Zoltan Kiss , Jesse Gross , pshelar@nicira.com, dev@openvswitch.org CC: xen-devel@lists.xenproject.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] openvswitch: Orphan frags before sending to userspace via Netlink to avoid guest stall References: <1393615016-9187-1-git-send-email-zoltan.kiss@citrix.com> In-Reply-To: <1393615016-9187-1-git-send-email-zoltan.kiss@citrix.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/28/2014 08:16 PM, Zoltan Kiss wrote: > The kernel datapath now switched to zerocopy Netlink messages, but that also > means that the pages on frags array are sent straight to userspace. If those > pages came outside the kernel, we have to swap them out with local copies. > > Signed-off-by: Zoltan Kiss > --- > net/openvswitch/datapath.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c > index 36f8872..ffb563c 100644 > --- a/net/openvswitch/datapath.c > +++ b/net/openvswitch/datapath.c > @@ -464,6 +464,12 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb, > } > nla->nla_len = nla_attr_size(skb->len); > > + if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) { > + err = -ENOMEM; > + skb_tx_error(skb); > + goto out; > + } > + > skb_zerocopy(user_skb, skb, skb->len, hlen); > > /* Pad OVS_PACKET_ATTR_PACKET if linear copy was performed */ How about we move the call to skb_orphan_frags() into skb_zerocopy() itself and call it before we actually reference the frags? It's not just OVS affected but nfqueue as well.