From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pmxout2.rz.tu-bs.de (pmxout2.rz.tu-bs.de [134.169.4.152]) (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 152DE25228C for ; Wed, 17 Dec 2025 19:05:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=134.169.4.152 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765998336; cv=none; b=aOKi4aWAf3B38KgvqqGITd7NdxuIfm3urMuXEyI0vrHO9GPE3QAdVo77ScRUCJ0cNKSj1PMf3zQde2hDTuK7m0Fx7jucQx+KLhebW821IaitrDP6T2uaYv5+UpiRVdLC+LmPQpomPuRe6gmNXQyzDVgNZPKBaH7/bVkCFpSuBS4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765998336; c=relaxed/simple; bh=+O5opAMvMYw9gbQqcIzmESWpm5bE6wHXpQKRfAChMl4=; h=Message-ID:Date:MIME-Version:Subject:From:To:CC:References: In-Reply-To:Content-Type; b=JpprPNqcaHEuyOUG8BJKXZzbHMRUavQcPfCH6fPOsu3d/QwmOCGMg/GDZOxhJHeToKlziE3cMt5eiDD0vBdAcvtZgofB29ovADqSBQLarxX2C69hJb63MkdinRyJFAcJk0lu8b9vCWlp8JgsdTsmIhalAzmkk8UqOWkU2gGNIaA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=tu-bs.de; spf=pass smtp.mailfrom=tu-braunschweig.de; dkim=pass (2048-bit key) header.d=tu-bs.de header.i=@tu-bs.de header.b=C83ZiJlL; arc=none smtp.client-ip=134.169.4.152 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=tu-bs.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=tu-braunschweig.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=tu-bs.de header.i=@tu-bs.de header.b="C83ZiJlL" X-KumoRef: eyJfQF8iOiJcXF8vIiwicmVjaXBpZW50IjoibGludXgta2VybmVsQHZnZXIua2VybmVsLm9yZyJ9 DKIM-Signature: v=1; a=rsa-sha256; d=tu-bs.de; s=exchange_neu; c=relaxed/relaxed; bh=d0brvDdV879BtZDkbJRmN93ySaqMZ4lI+qtZFdHyR7E=; h=from:from:reply-to:subject:subject:date:date:to:to:cc:cc:resent-date: resent-from:resent-to:resent-cc:in-reply-to:in-reply-to:references: references:list-id:list-help:list-unsubscribe:list-subscribe:list-post: list-owner:list-archive; t=1765998324; b=C83ZiJlLIcxG5s1DllG50ijOIFAlu3w3kfKe3ONDZAkn3rVCFLodZK34iLmPVRH/msXbTiPEl mmC/jJFEwLwLTLrurPiZb71+ZSx1aTW2+ZC7ihZEcAu2kWtir68PFeoOMJkBOjnHh1MlFLvhKNz AZocgkzPSApjA419uGPPrFJUsUtG3exLS9wKIw9fWMI0Jd+iRrN+gwKY+4d6fcetF5J+E/fZEHF SjJcCdTddyiL/qK/Wo/xYsAz6kN20Hg57gkq904WLHbyQbTVxntJQe+Txo6JMYAiV/yIksmEx7g fLKrtAx7h6rZR066BZUi+L2FH5hW9Ysr8ksannbq7vog==; Received: from pegasus01.ad.tu-bs.de (134.169.4.141) by kumo1.rz.tu-bs.de (KumoMTA 134.169.4.163) with ESMTPS (TLSv1_2:TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 57c9c461db7b11f0a3237edee6c2bcb2 for ; Wed, 17 Dec 2025 19:05:24 +0000 Received: from Pegasus02.ad.tu-bs.de (2001:638:602:f012::3) by Pegasus01.ad.tu-bs.de (2001:638:602:f012::2) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.35; Wed, 17 Dec 2025 20:05:24 +0100 Received: from [192.168.178.23] (134.169.9.110) by Pegasus02.ad.tu-bs.de (2001:638:602:f012::3) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.35; Wed, 17 Dec 2025 20:05:23 +0100 Message-ID: <0f7f3317-7a96-44f2-a3e7-a49f75bcd6aa@tu-bs.de> Date: Wed, 17 Dec 2025 20:05:23 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] Potential problem in qspinlock due to mixed-size accesses From: Thomas Haas To: Alan Stern , Andrea Parri , Will Deacon , Peter Zijlstra , Boqun Feng , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , "Paul E. McKenney" , Akira Yokosawa , "Daniel Lustig" , Joel Fernandes , , , CC: , , "r.maseli@tu-bs.de" References: Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: Pegasus08.ad.tu-bs.de (2001:638:602:f012::9) To Pegasus02.ad.tu-bs.de (2001:638:602:f012::3) On 12.06.25 16:55, Thomas Haas wrote: > We have been taking a look if mixed-size accesses (MSA) can affect the > correctness of qspinlock. > We are focusing on aarch64 which is the only memory model with MSA > support [1]. > For this we extended the dartagnan [2] tool to support MSA and now it > reports liveness, synchronization, and mutex issues. --- cut off --- ARM has recently fixed the issue on their side by strengthening the memory model (see https://github.com/herd/herdtools7/commit/2b7921a44a61766e23a1234767d28af696b436a0) With the updated ARM-MSA model, Dartagnan does no longer find violations in qspinlock. No patches needed :) With best regards, Thomas