From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753280Ab3KTKe0 (ORCPT ); Wed, 20 Nov 2013 05:34:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:1479 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750834Ab3KTKeU (ORCPT ); Wed, 20 Nov 2013 05:34:20 -0500 Date: Wed, 20 Nov 2013 12:37:29 +0200 From: "Michael S. Tsirkin" To: Jason Wang Cc: rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Michael Dalton , Eric Dumazet Subject: Re: [PATCH net 2/3] virtio-net: fix num calculation on frag skb allocation failure Message-ID: <20131120103729.GG19341@redhat.com> References: <1384938447-3775-1-git-send-email-jasowang@redhat.com> <1384938447-3775-2-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1384938447-3775-2-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? > --- > 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