From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9329E424671 for ; Thu, 16 Jul 2026 14:48:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784213324; cv=none; b=bD6w9mpCs9W4gEP7h3brr3fmyoSmHkjorefu+hQlF++MDDIx6Ng3LBX3BcessAfvOSdYln7YUzAiLkvnCs3ldit5t3zMdRmYt1TndWoppv6LAGYF8dnyCSDdI2SbHYD+qgRmzMV+z1PWpX7CZzVXpX2UkPCWXAau9OqUvC6PbuQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784213324; c=relaxed/simple; bh=+XRvv4MQceldV2fwBOvUUPmboGF+ffAPO7oPzG0p4Jg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=adyyJWIKdj4jW3aDVX2pXZEGmQPPk6bSAx575vb30w3ROg0ChGQNJl+2oN32KpWmtRMLFXiFWuQviRADPVwcHfBINxCgEk3wPT197izkrLConH8vqjWoeisAa/lseuuPrTdXNRN0TJKU9Af3LXvWGC8oWgu3qcEVAiyAQdY/MPQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gBPBr/0Y; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gBPBr/0Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA3701F000E9; Thu, 16 Jul 2026 14:48:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784213323; bh=zQ4TnNCbrQSEpvT7HgWJyZhrbmf2/9fI9VcdMrCRoZg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gBPBr/0YzOp6KqfWEL8WAHCvjAvXZqGgHPSNMir6xRdfD+chun1vCYYy0A9fvwdh/ 4jd2snpQEewh79hrjoJ02092/cilVTNVWoON7yRQvxvzO7ihtX4F7rzAmYNat4yvf4 Ql58V/CQXReg2UoxAnewHV0xrFLdg2n2n6xTQHwgdWq0Hd/+HpCtoc//2IDiOx+h/j FMmfavUhqyd09BtRmy9Fol1RoQQPUAp/gW8jJNfwAJxWDhYtbP9jWIV8NxdCevBiaP uR/0meZXM7+bMBoesITAyhb4HLcD6x4dLpzT8mH64py0FkVIApkB/W90fjjurpy51O vXWCiS5KxnTjQ== From: Simon Horman To: alice.kernel@fastmail.im Cc: Simon Horman , daniel@iogearbox.net, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, lucien.xin@gmail.com, willemdebruijn.kernel@gmail.com, willemb@google.com, dsahern@kernel.org, razor@blackwall.org, shuah@kernel.org, stfomichev@gmail.com, andrew+netdev@lunn.ch, fw@strlen.de, netdev@vger.kernel.org, alice@isovalent.com Subject: Re: [PATCH net-next v9 8/9] geneve: Enable BIG TCP packets Date: Thu, 16 Jul 2026 15:48:31 +0100 Message-ID: <20260716144830.337991-2-horms@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260710134242.216538-9-alice.kernel@fastmail.im> References: <20260710134242.216538-9-alice.kernel@fastmail.im> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This is an AI-generated review of your patch. The human sending this email has considered the AI review valid, or at least plausible. Full review at: https://sashiko.dev --- --- Patch [8]: [PATCH net-next v9 8/9] geneve: Enable BIG TCP packets --- commit d560b2b7c8bd97bea9e23790fdfc21cfe031b961 Author: Alice Mikityanska geneve: Enable BIG TCP packets In Cilium we do support BIG TCP, but so far the latter has only been enabled for direct routing use-cases. A lot of users rely on Cilium with vxlan/geneve tunneling though. The underlying kernel infra for tunneling has not been supporting BIG TCP up to this point. > diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c > index 011bf9d833caf..a1639ad53077e 100644 > --- a/drivers/net/geneve.c > +++ b/drivers/net/geneve.c > @@ -1745,6 +1745,8 @@ static void geneve_setup(struct net_device *dev) > dev->max_mtu = IP_MAX_MTU - GENEVE_BASE_HLEN - dev->hard_header_len; > > netif_keep_dst(dev); > + netif_set_tso_max_size(dev, GSO_MAX_SIZE); > + [Severity: High] This is a pre-existing issue, but by enabling BIG TCP on Geneve, will it expose a bug where valid BIG TCP packets are incorrectly dropped? In geneve_post_decap_hint(), there is a legacy size check that rejects packets aggregated by GRO to sizes >= 65536 bytes: drivers/net/geneve.c:geneve_post_decap_hint() { ... total_len = skb->len - gro_hint->nested_nh_offset; if (total_len >= GRO_LEGACY_MAX_SIZE) return -E2BIG; ... } When BIG TCP is enabled and the Geneve tunnel is configured with gro_hint, large flows are aggregated by GRO into packets exceeding 64KB. This will hit the legacy check and return -E2BIG, causing packet loss for large flows. > dev->priv_flags &= ~IFF_TX_SKB_SHARING; > dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE; > dev->lltx = true;