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 AC7963CF40 for ; Mon, 12 Feb 2024 15:02:15 +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=1707750135; cv=none; b=ZCEuLtrvjQ13gkZFQe+BsxQo67Ur4MnpFFm597ifZ+IjcoeBvkIsKMMyLIDL+djYTvDh/Wj+BjX0ZU7fGxecMcZJrdBzNBlUSa4e6Yx1F1kNmreJMEXZ/yqi/VbA920xgwZKmj+AP5jHQqf28fXkzjZJl+KIG0NFWl4XJNSqPOo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707750135; c=relaxed/simple; bh=ioIAfMxeMXCPkn6xMdt9uZcKoqspLYKHVP1IESePhSA=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=gwFEiTUYv4hWLYPf2n2LmB7s4WJI+Z6EqqlnSkrEsMKVQj8K0ePZ7gHwm1fZFiWSoNDoqt1xg58uS1LnwDxPguU61Eq8NxlMEXvYTVmwAl8lYgcWEpcG2pZXIQsqab0eWqFFxKLOTwh/XwJFmHiU1cdsKEtRbMuVQeKmdXKH3wc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=r2TCOHAh; 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="r2TCOHAh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA5C3C433F1; Mon, 12 Feb 2024 15:02:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1707750135; bh=ioIAfMxeMXCPkn6xMdt9uZcKoqspLYKHVP1IESePhSA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=r2TCOHAh6OpC4XVzu4h5N0JyViOrWBQC+ykG03+S1PMOWGyds7rkH1wbOX/O/4ROp 4G1uVjokwe7zXkSZlCy8+FTb1v8pvRPzpDzZValjc2ht4bNBMFAHpjq9j4hKiVKvBf l43MMJ+P78nLTzaamXSA0M7QMRVg/PwyoLUoONjOejsOHXXJrxgPzbD6rRJXIRQVYQ BcvxVAE5ehW87M8+5D1o8No/H5Dz74b2nT46AvoidXypACZQ0azF/EIRy+dCQULa1t cDheyLvtXkMi7z7Joy727k4Ecf0mIlBk6luYN876xArnXvXtb+5wNbNJAmBQaA7YPo gCg2xiPiz1gFQ== Date: Mon, 12 Feb 2024 07:02:13 -0800 From: Jakub Kicinski To: Jamal Hadi Salim Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, Marcelo Ricardo Leitner , Davide Caratti , xiyou.wangcong@gmail.com, jiri@resnulli.us, shmulik.ladkani@gmail.com Subject: Re: [PATCH net] net/sched: act_mirred: use the backlog for mirred ingress Message-ID: <20240212070213.504d6930@kernel.org> In-Reply-To: References: <20240209235413.3717039-1-kuba@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 Mon, 12 Feb 2024 09:51:20 -0500 Jamal Hadi Salim wrote: > > The test Davide added in commit ca22da2fbd69 ("act_mirred: use the backlog > > for nested calls to mirred ingress") hangs our testing VMs every 10 or so > > runs, with the familiar tcp_v4_rcv -> tcp_v4_rcv deadlock reported by > > lockdep. > > > > In the past there was a concern that the backlog indirection will > > lead to loss of error reporting / less accurate stats. But the current > > workaround does not seem to address the issue. > > Let us run some basic tests on this first - it's a hairy spot. Thanks! > Also, IIRC Cong had some reservations about this in the past. Can't > remember what they were. He was worried that the overlimits stats are no longer counted when we decouple (and Davide's selftest actually checks for that so I had to modify it). I'm not married to the solution in any way but bugs much less serious get three letter acronyms, we can't pretend this one doesn't exist.