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Wed, 04 Sep 2024 01:58:41 -0700 (PDT) Received: from shivania.eng.vmware.com ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2da6fb086cfsm2813801a91.24.2024.09.04.01.58.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Sep 2024 01:58:41 -0700 (PDT) From: Shivani Agarwal To: stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, ajay.kaher@broadcom.com, alexey.makhalov@broadcom.com, vasavi.sirnapalli@broadcom.com, Breno Leitao , Heng Qi , Sasha Levin , Shivani Agarwal Subject: [PATCH v6.6] virtio_net: Fix napi_skb_cache_put warning Date: Wed, 4 Sep 2024 01:58:29 -0700 Message-Id: <20240904085829.14684-1-shivani.agarwal@broadcom.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Breno Leitao [ Upstream commit f8321fa75102246d7415a6af441872f6637c93ab ] 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+0x82/0= x4b0 __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 Reviewed-by: Jakub Kicinski Acked-by: Michael S. Tsirkin Acked-by: Jason Wang Reviewed-by: Heng Qi Link: https://patch.msgid.link/20240712115325.54175-1-leitao@debian.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin [Shivani: Modified to apply on v6.6.y] Signed-off-by: Shivani Agarwal --- 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 51ade909c84f..bc01f2dafa94 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2140,7 +2140,7 @@ static int virtnet_receive(struct receive_queue *rq, = int budget, return packets; } =20 -static void virtnet_poll_cleantx(struct receive_queue *rq) +static void virtnet_poll_cleantx(struct receive_queue *rq, int budget) { struct virtnet_info *vi =3D rq->vq->vdev->priv; unsigned int index =3D vq2rxq(rq->vq); @@ -2158,7 +2158,7 @@ static void virtnet_poll_cleantx(struct receive_queue= *rq) =20 do { virtqueue_disable_cb(sq->vq); - free_old_xmit_skbs(sq, true); + free_old_xmit_skbs(sq, !!budget); } while (unlikely(!virtqueue_enable_cb_delayed(sq->vq))); =20 if (sq->vq->num_free >=3D 2 + MAX_SKB_FRAGS) @@ -2177,7 +2177,7 @@ static int virtnet_poll(struct napi_struct *napi, int= budget) unsigned int received; unsigned int xdp_xmit =3D 0; =20 - virtnet_poll_cleantx(rq); + virtnet_poll_cleantx(rq, budget); =20 received =3D virtnet_receive(rq, budget, &xdp_xmit); =20 @@ -2280,7 +2280,7 @@ static int virtnet_poll_tx(struct napi_struct *napi, = int budget) txq =3D netdev_get_tx_queue(vi->dev, index); __netif_tx_lock(txq, raw_smp_processor_id()); virtqueue_disable_cb(sq->vq); - free_old_xmit_skbs(sq, true); + free_old_xmit_skbs(sq, !!budget); =20 if (sq->vq->num_free >=3D 2 + MAX_SKB_FRAGS) netif_tx_wake_queue(txq); --=20 2.39.4