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Tsirkin" To: Xuan Zhuo Cc: netdev@vger.kernel.org, Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , virtualization@lists.linux-foundation.org Subject: Re: [PATCH net] virtio_net: fix missing dma unmap for resize Message-ID: <20231109070359-mutt-send-email-mst@kernel.org> References: <20231106081832.668-1-xuanzhuo@linux.alibaba.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231106081832.668-1-xuanzhuo@linux.alibaba.com> On Mon, Nov 06, 2023 at 04:18:32PM +0800, Xuan Zhuo wrote: > For rq, we have three cases getting buffers from virtio core: > > 1. virtqueue_get_buf{,_ctx} > 2. virtqueue_detach_unused_buf > 3. callback for virtqueue_resize > > But in commit 295525e29a5b("virtio_net: merge dma operations when > filling mergeable buffers"), I missed the dma unmap for the #3 case. > > That will leak some memory, because I did not release the pages referred > by the unused buffers. > > If we do such script, we will make the system OOM. > > while true > do > ethtool -G ens4 rx 128 > ethtool -G ens4 rx 256 > free -m > done > > Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable buffers") > Signed-off-by: Xuan Zhuo > --- > drivers/net/virtio_net.c | 43 ++++++++++++++++++++-------------------- > 1 file changed, 22 insertions(+), 21 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index d16f592c2061..6423a3a007ce 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -408,6 +408,17 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask) > return p; > } > > +static void virtnet_rq_free_buf(struct virtnet_info *vi, > + struct receive_queue *rq, void *buf) > +{ > + if (vi->mergeable_rx_bufs) > + put_page(virt_to_head_page(buf)); > + else if (vi->big_packets) > + give_pages(rq, buf); > + else > + put_page(virt_to_head_page(buf)); > +} > + > static void enable_delayed_refill(struct virtnet_info *vi) > { > spin_lock_bh(&vi->refill_lock); > @@ -634,17 +645,6 @@ static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx) > return buf; > } > > -static void *virtnet_rq_detach_unused_buf(struct receive_queue *rq) > -{ > - void *buf; > - > - buf = virtqueue_detach_unused_buf(rq->vq); > - if (buf && rq->do_dma) > - virtnet_rq_unmap(rq, buf, 0); > - > - return buf; > -} > - > static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32 len) > { > struct virtnet_rq_dma *dma; > @@ -1764,7 +1764,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, > if (unlikely(len < vi->hdr_len + ETH_HLEN)) { > pr_debug("%s: short packet %i\n", dev->name, len); > DEV_STATS_INC(dev, rx_length_errors); > - virtnet_rq_free_unused_buf(rq->vq, buf); > + virtnet_rq_free_buf(vi, rq, buf); > return; > } > > @@ -4034,14 +4034,15 @@ static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf) > static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf) > { > struct virtnet_info *vi = vq->vdev->priv; > + struct receive_queue *rq; > int i = vq2rxq(vq); > > - if (vi->mergeable_rx_bufs) > - put_page(virt_to_head_page(buf)); > - else if (vi->big_packets) > - give_pages(&vi->rq[i], buf); > - else > - put_page(virt_to_head_page(buf)); > + rq = &vi->rq[i]; > + > + if (rq->do_dma) > + virtnet_rq_unmap(rq, buf, 0); > + > + virtnet_rq_free_buf(vi, rq, buf); > } > So we have virtnet_rq_free_buf which sounds like it should free any buf, and we have virtnet_rq_free_unused_buf which is only for unused. Or so it would seem from names but this is not true. Better function names? > static void free_unused_bufs(struct virtnet_info *vi) > @@ -4057,10 +4058,10 @@ static void free_unused_bufs(struct virtnet_info *vi) > } > > for (i = 0; i < vi->max_queue_pairs; i++) { > - struct receive_queue *rq = &vi->rq[i]; > + struct virtqueue *vq = vi->rq[i].vq; > > - while ((buf = virtnet_rq_detach_unused_buf(rq)) != NULL) > - virtnet_rq_free_unused_buf(rq->vq, buf); > + while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) > + virtnet_rq_free_unused_buf(vq, buf); > cond_resched(); > } > } > -- > 2.32.0.3.g01195cf9f