From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752914Ab3KTMIz (ORCPT ); Wed, 20 Nov 2013 07:08:55 -0500 Received: from mx3-phx2.redhat.com ([209.132.183.24]:46508 "EHLO mx3-phx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751390Ab3KTMIx convert rfc822-to-8bit (ORCPT ); Wed, 20 Nov 2013 07:08:53 -0500 Date: Wed, 20 Nov 2013 07:08:50 -0500 (EST) From: Jason Wang To: "Michael S. Tsirkin" Cc: rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Michael Dalton , Eric Dumazet Message-ID: <734327384.27426189.1384949330819.JavaMail.root@redhat.com> In-Reply-To: <20131120103729.GG19341@redhat.com> References: <1384938447-3775-1-git-send-email-jasowang@redhat.com> <1384938447-3775-2-git-send-email-jasowang@redhat.com> <20131120103729.GG19341@redhat.com> Subject: Re: [PATCH net 2/3] virtio-net: fix num calculation on frag skb allocation failure MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Originating-IP: [10.5.82.11] X-Mailer: Zimbra 8.0.3_GA_5664 (ZimbraWebClient - GC31 (Win)/8.0.3_GA_5664) Thread-Topic: virtio-net: fix num calculation on frag skb allocation failure Thread-Index: 1o76VnPAC/IrTF8D8j9rvTk81BbpHA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- 原始邮件 ----- > On Wed, Nov 20, 2013 at 05:07:26PM +0800, Jason Wang wrote: > > We need decrease the rq->num after we can get a buf through > > virtqueue_get_buf() even if we could not allocate frag skb. Otherwise, the > > refill routine won't be triggered under heavy memory stress since the > > driver may > > still think there's enough room. > > > > This bug was introduced by commit 2613af0ed18a11d5c566a81f9a6510b73180660a > > (virtio_net: migrate mergeable rx buffers to page frag allocators). > > > > Cc: Rusty Russell > > Cc: Michael S. Tsirkin > > Cc: Michael Dalton > > Cc: Eric Dumazet > > Signed-off-by: Jason Wang > > So let's wrap virtqueue_get_buf to make sure we get it right? > Ok. good idea. > > --- > > The patch was needed for 3.12 stable. > > --- > > drivers/net/virtio_net.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index 24fd502..de1d6ca 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -333,6 +333,7 @@ static int receive_mergeable(struct receive_queue *rq, > > struct sk_buff *head_skb) > > head_skb->dev->stats.rx_length_errors++; > > return -EINVAL; > > } > > + --rq->num; > > if (unlikely(len > MERGE_BUFFER_LEN)) { > > pr_debug("%s: rx error: merge buffer too long\n", > > head_skb->dev->name); > > @@ -367,7 +368,6 @@ static int receive_mergeable(struct receive_queue *rq, > > struct sk_buff *head_skb) > > skb_add_rx_frag(curr_skb, num_skb_frags, page, > > offset, len, MERGE_BUFFER_LEN); > > } > > - --rq->num; > > } > > return 0; > > } > > -- > > 1.8.3.2 >