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 733423A1B5; Sat, 22 Nov 2025 01:55:57 +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=1763776557; cv=none; b=cH0j9xB7QEGHrPFt04iEpCg2ufg7orvBmfRP8prCiaDqyj7gWBhgyZh7f9Dtq878PsKopW/KCQOPKD5JmSF9DrJrZf3fupBQbvzmr70v6ZFwX/jGzNLaO3Uv23NA0LWJxqW2dz5Z22MUg8J8xfWGQvoj3mrmhYlaqKP0sKQjCYo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763776557; c=relaxed/simple; bh=PdHFwgfBrSp7W4J11DZPHxYZQV/N11nae/5XIfCwoeQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Hi3J1+jKDG9aBHSF9tkn7vxT+VtSY1d9wm3r4VRpmWxfrliNv/FpLNfsbTxRmZlxyDMOtZ8sEnWp4Bt15GL7Tgv6jFjGkzOztiwlTmmu95dWQLCbhTEa08JI9+9CqvtiyAYt1lPYVZZnXeRnA5G48+E4f5kCJcw4T2xZeO6V3Ko= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gPgu8nPR; 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="gPgu8nPR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F017FC4CEF1; Sat, 22 Nov 2025 01:55:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763776557; bh=PdHFwgfBrSp7W4J11DZPHxYZQV/N11nae/5XIfCwoeQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=gPgu8nPRH9VcOmVtjXaAq4N9k/KBdcnvUZI+AJhlqNkTQdMbnwlWvyNqyH7SBsXGX iSRYbnTmsyJ10PJaCeSAV4Ee+EFU9QEauE6IF5TroiZ0iAgkLpTK34sHRvBi+58pK2 jDyjqT+/mR3L2ivVOphRDj5s7v64Jiygz2CgOegOJ1pG0YKvPHWvGfy2HseXeU4NW5 zc+o403dWTCpBifLU8EC+VofisaacJWdUr048Mph/MSCl01pjYguWtzI9klSihWPOy Yu+HAK43YvoToPmpsCl1/kjHt3kynCSH4x+Og32wiuPzXK9Doh+Daq5Wuu0RKdNzjw IIUnP8cuTfTTQ== Date: Fri, 21 Nov 2025 17:55:56 -0800 From: Jakub Kicinski To: Stephen Hemminger , Jamal Hadi Salim Cc: Cong Wang , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, will@willsroot.io, jschung2@proton.me, savy@syst3mfailure.io Subject: Re: [Bug 220774] New: netem is broken in 6.18 Message-ID: <20251121175556.26843d75@kernel.org> In-Reply-To: <20251121161322.1eb61823@phoenix.local> References: <20251110123807.07ff5d89@phoenix> <20251121161322.1eb61823@phoenix.local> 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 Fri, 21 Nov 2025 16:13:22 -0800 Stephen Hemminger wrote: > On Fri, 21 Nov 2025 13:45:06 -0800 > Cong Wang wrote: > > > On Fri, Nov 21, 2025 at 07:52:37AM -0500, Jamal Hadi Salim wrote: > > > > > jschung2@proton.me: Can you please provide more details about what you > > > are trying to do so we can see if a different approach can be > > > prescribed? > > > > > > > An alternative approach is to use eBPF qdisc to replace netem, but: > > 1) I am not sure if we could duplicate and re-inject a packet in eBPF Qdisc > > 2) I doubt everyone wants to write eBPF code when they already have a > > working cmdline. > > > > BTW, Jamal, if your plan is to solve them one by one, even if it could work, > > it wouldn't scale. There are still many users don't get hit by this > > regression yet (not until hitting LTS or major distro). > > The bug still needs to be fixed. > eBPF would still have the same kind of issues. I guess we forgot about mq.. IIRC mq doesn't come into play in duplication, we should be able to just adjust the check to allow the mq+netem hierarchy?