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 A1B8628FF; Thu, 29 May 2025 00:23:08 +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=1748478188; cv=none; b=ees6qbAZCob0Zxx4IalBr96U+/WJyyUX34x11oeeakXCAL5TRb8RRBLlNfCRL8QEqjh8tZqWNrBLjnr3AgB7Yy5gibbRMwc3PF1LJJU7S4objkC1CzSTpvTujqxX/bKerDHj0chy1WqKio8fNRkkxdH2JTyjFHnL6tyHE84JnfM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748478188; c=relaxed/simple; bh=YL/MCDVOQdyzpgzoixJs0Qwj1/oOVGX+VAX6mD/kWLo=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=h9Xz9p4osyoLxQUR7bXEjsI4ZTIntAk0mdW3MNft0ikws1KTmStQczUsxccjBMWa6UZyF1vmV8I81n88XPg8BGReOVKrts15bb/uoY7Ew1XdiTyXX99LoHjJDJC3ZyRAXZmbaOSJWpzFEPhpx9orFGl0qbR6D5zjOnLKHVgmTTw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=stku6XPU; 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="stku6XPU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C8B6C4CEE3; Thu, 29 May 2025 00:23:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1748478188; bh=YL/MCDVOQdyzpgzoixJs0Qwj1/oOVGX+VAX6mD/kWLo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=stku6XPURgSvdEIz+xuO8mtU9B7POoboSNDw9e8fmEAQxwAlgv95hAm9g0GoXdl4B F3b0wotb8jouCZT/ILHSeSnz1i5Q3cw3cWv3vukyDUq/cD8ayhqQFjuTw9H2gAH6cL oGCjFoX4t1FRB41yBoMYAVgQQ9VdPuaKb+p/xKpFkMhPxqxwSKoTKJTb/Qt1yW9kn5 61KtCcYeFVSxRfxWlvL15LnFYfGuXt6dtzZmvCE8NQIinoL3KaSrb09gPpkzoUCB/D pZXWgo3lVLYsHT4wls9tIDbokGSzUPYRBXDdAo8pfjJmVjpbmZKsxY6W+88TK9LfmB 9YPqXN67tX8OQ== Date: Wed, 28 May 2025 17:23:06 -0700 From: Jakub Kicinski To: Mina Almasry Cc: Tony Nguyen , davem@davemloft.net, pabeni@redhat.com, edumazet@google.com, andrew+netdev@lunn.ch, netdev@vger.kernel.org, Alexander Lobakin , maciej.fijalkowski@intel.com, magnus.karlsson@intel.com, michal.kubiak@intel.com, przemyslaw.kitszel@intel.com, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, horms@kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH net-next 01/16] libeth: convert to netmem Message-ID: <20250528172306.18c1482a@kernel.org> In-Reply-To: References: <20250520205920.2134829-1-anthony.l.nguyen@intel.com> <20250520205920.2134829-2-anthony.l.nguyen@intel.com> <20250527185749.5053f557@kernel.org> 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, 27 May 2025 20:49:33 -0700 Mina Almasry wrote: > > If you don't want to have to validate the low bit during netmem -> page > > conversions - you need to clearly maintain the separation between > > the two in the driver. These __netmem_to_page() calls are too much of > > a liability. > > Would it make sense to add a DEBUG_NET_WARN_ON_ONCE to > __netmem_to_page to catch misuse in a driver independent way? Or is > that not good enough because there may be latent issues only hit in > production where the debug is disabled. Yes, DEBUG_NET_WARN_ON_ONCE() is not ideal. The condition may trigger pretty rarely, and what are we saving? A single branch per packet on a HW-GRO capable device? Isn't the netmem vs page confusion here primarily because we want to use the same struct to hold head and payload pages?