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[2a03:2880:30ff:2::face:b00c]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-594bbe2d0f4sm4570995a12.35.2024.07.12.04.54.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jul 2024 04:54:20 -0700 (PDT) From: Breno Leitao To: "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: rbc@meta.com, horms@kernel.org, virtualization@lists.linux.dev (open list:VIRTIO CORE AND NET DRIVERS), netdev@vger.kernel.org (open list:NETWORKING DRIVERS), linux-kernel@vger.kernel.org (open list) Subject: [PATCH net-next] virtio_net: Fix napi_skb_cache_put warning Date: Fri, 12 Jul 2024 04:53:25 -0700 Message-ID: <20240712115325.54175-1-leitao@debian.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit After the commit bdacf3e34945 ("net: Use nested-BH locking for napi_alloc_cache.") was merged, the following warning began to appear: WARNING: CPU: 5 PID: 1 at net/core/skbuff.c:1451 napi_skb_cache_put+0x82/0x4b0 __warn+0x12f/0x340 napi_skb_cache_put+0x82/0x4b0 napi_skb_cache_put+0x82/0x4b0 report_bug+0x165/0x370 handle_bug+0x3d/0x80 exc_invalid_op+0x1a/0x50 asm_exc_invalid_op+0x1a/0x20 __free_old_xmit+0x1c8/0x510 napi_skb_cache_put+0x82/0x4b0 __free_old_xmit+0x1c8/0x510 __free_old_xmit+0x1c8/0x510 __pfx___free_old_xmit+0x10/0x10 The issue arises because virtio is assuming it's running in NAPI context even when it's not, such as in the netpoll case. To resolve this, modify virtnet_poll_tx() to only set NAPI when budget is available. Same for virtnet_poll_cleantx(), which always assumed that it was in a NAPI context. Fixes: df133f3f9625 ("virtio_net: bulk free tx skbs") Suggested-by: Jakub Kicinski Signed-off-by: Breno Leitao --- drivers/net/virtio_net.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 0b4747e81464..fb1331827308 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2341,7 +2341,7 @@ static int virtnet_receive(struct receive_queue *rq, int budget, return packets; } -static void virtnet_poll_cleantx(struct receive_queue *rq) +static void virtnet_poll_cleantx(struct receive_queue *rq, int budget) { struct virtnet_info *vi = rq->vq->vdev->priv; unsigned int index = vq2rxq(rq->vq); @@ -2359,7 +2359,7 @@ static void virtnet_poll_cleantx(struct receive_queue *rq) do { virtqueue_disable_cb(sq->vq); - free_old_xmit(sq, txq, true); + free_old_xmit(sq, txq, !!budget); } while (unlikely(!virtqueue_enable_cb_delayed(sq->vq))); if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) { @@ -2404,7 +2404,7 @@ static int virtnet_poll(struct napi_struct *napi, int budget) unsigned int xdp_xmit = 0; bool napi_complete; - virtnet_poll_cleantx(rq); + virtnet_poll_cleantx(rq, budget); received = virtnet_receive(rq, budget, &xdp_xmit); rq->packets_in_napi += received; @@ -2526,7 +2526,7 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget) txq = netdev_get_tx_queue(vi->dev, index); __netif_tx_lock(txq, raw_smp_processor_id()); virtqueue_disable_cb(sq->vq); - free_old_xmit(sq, txq, true); + free_old_xmit(sq, txq, !!budget); if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) { if (netif_tx_queue_stopped(txq)) { -- 2.43.0