From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9DE2FCA6F for ; Thu, 2 Apr 2026 00:38:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775090324; cv=none; b=hxZKzUdYVraMz3KyU7tFI2V36LAhjsCTSm2GV2rmKUmhF4hweljcJnc2yq0gyYItlmEuVTORH3XEJz13C6GQaWas++DEj/7NlGW+sRrEwZo/pqvS8HY8p/8IsUbtRUqXEAM9lVpRMQNZjeMPHEYq5b2lU5uF5dViq8h59pbIZcI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775090324; c=relaxed/simple; bh=yy629Hf89kRkCloYSbiQgvfX/GNhce78QZJyjjjFBQ0=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=U0Blna9IIKqgiRB/TXtnzm6usRKvcrkoLFrI2PMK/06/zA005ocay0kfsl1Q6I2QrZCaqvJD0iiCsiYQMutn3vPxq8dEsL0G39EnLQhRmHbnp1BcpgNia6viTzjoTi9Dj+9rW06IN8uViDicZar61N6zAqNlE1nVUMQUl+vH0os= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sX4HxWjt; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sX4HxWjt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 32E35C4CEF7; Thu, 2 Apr 2026 00:38:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775090324; bh=yy629Hf89kRkCloYSbiQgvfX/GNhce78QZJyjjjFBQ0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=sX4HxWjtFN/PMdnAve1yL6OuQr1tt4IB1GguN98L5DIrwgnxojcRbgU3shFiSS3ej riBDZshIOzJpVTZTHZOhnHoHv0aguMqELKr7QV+ttjtLGItBHE0KoFHPryBWCc9jh9 KrFWaJ8TUkkfjF2cJl/BjymdWrKEyjx9uB9cf6e/JIW8R2wME/qYC7RpDMiz7W26+a W564ICsD8d6/En4gBqPJsAAOgxQhCxjaW2qkzupdEqMdLxyxojqpU2VbuIxrghuQB4 aUVqqoCypxSBMlfqFIPbpCjbJCzMrpN1vYAlfcBKbv3xYBqly84diu/FXj6ON9haNO cwSoMrbCh9AJg== Date: Wed, 1 Apr 2026 17:38:43 -0700 From: Jakub Kicinski To: Chris Arges Cc: Weiming Shi , Eric Dumazet , Paolo Abeni , netdev@vger.kernel.org, kernel-team@cloudflare.com, jgriege@cloudflare.com Subject: Re: [REGRESSION] net: add xmit recursion limit to tunnel xmit functions Message-ID: <20260401173843.7a2bb607@kernel.org> In-Reply-To: References: 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-Transfer-Encoding: 7bit On Tue, 31 Mar 2026 15:09:33 -0500 Chris Arges wrote: > Commit 6f1a9140ecda ("net: add xmit recursion limit to tunnel xmit functions") > introduces a regression in our systems using legitimate multi-level tunnel > encapsulation stacks. Our testing was with stable 6.12.y and 6.18.y where this > patch was backported. > > One of the usecases we have are packets being sent to a GRE device, then > MPLS/LWT route, then IPIP device, then SIT/FOU device. What we observed is that > packets are getting dropped at the last device and we get the message "Dead > loop on virtual device" sent from the iptunnel_xmit function. Last device meaning limit of 5 would have worked for you? I don't think there was any hard math behind the 4 so ++ on the limit may be simplest, but I defer to Paolo..