From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 197E43A5E87; Thu, 24 Sep 2026 09:34:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790242501; cv=none; b=QRjvwtFs0NJgi/eN/aLu40VYdr8iafbbh4jAl5cMXqiYT0QWFMC+WzIcfohm+gxYGUi30bXoL9AiTqKeXC8lWVbg0lH9gqXVsWkRMMpB1+lwvgqiGd9ej2pvq9T+A8c4IZyNvdljugIHHFscOzm+ZnGSy2mTcdPdpusgcxK9LxE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790242501; c=relaxed/simple; bh=IuX8jTTYJ8NyywhPtLRRV9sA1F7vf30GeNtA2COnEFE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=K4EWo0Isc9nHKaxoGo6t3cO/ItyQlkkq1UnrAvfMArwLSl2mjgr3mIs4Pe4Vvrkn87/tx+4gb+p6Oc/KdN7+8VrAboWxASZfdWEZbpwb2nbAJvxuRhjNeUVa+pYFw7Epg22aapAtg3f9O4WFLADfIqNaoTu8iJnU++8mC3dxd3g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=mUvZLLvq; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mUvZLLvq" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=NRGkWUe9619LvbBMEXcxaKtHAE3240PhPtEdXzFuBI0=; b=mUvZLLvqEJm2rhbWzt318A8xLn /F3bVNp4g/z1Dvo0f910YshdypY5yFoPkqAxpSxVQ9viIZ+at04qidhPVnvPrrvCOoVTfC2+eAc1i tIOFODo6WILfQjr11vsu/1g+rfxnfiNekeA+vjlt6uS+o2gXUg/Nt5kyLNLymsQFrFVBPKvrs069D 9vvu8aoG6W01JroueOFjYxUEHUiwg1VUg2Fd/1JSQDEZuF4jetwlVa7H6/phFjWDxO+s3ZkfQzlsb s/uDURDQm2bQYk0F35LlW7nw7dpuUU9CSavw6yuyaYVCs6TgYXUhgftO96RAdT956YWysP1F+Q0xF h91qRW5Q==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.99.2 #2 (Red Hat Linux)) id 1x9fqt-0000000FnDU-13e2; Thu, 24 Sep 2026 09:34:54 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 868D13006DD; Thu, 24 Sep 2026 11:34:50 +0200 (CEST) Date: Thu, 24 Sep 2026 11:34:50 +0200 From: Peter Zijlstra To: Brian Cain Cc: linux-kernel@vger.kernel.org, pierrick.bouvier@oss.qualcomm.com, paulmck@kernel.org, sid.manning@oss.qualcomm.com, linux-hexagon@vger.kernel.org, Ingo Molnar , Frederic Weisbecker , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= Subject: Re: [PATCH v2] smp: align struct __call_single_node to 8 bytes Message-ID: <20260924093450.GN2009045@noisy.programming.kicks-ass.net> References: <20260923154307.3625611-1-brian.cain@oss.qualcomm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260923154307.3625611-1-brian.cain@oss.qualcomm.com> On Wed, Sep 23, 2026 at 08:43:07AM -0700, Brian Cain wrote: > Consumers walking call_single_queue cast each node to call_single_data_t > and, given that type's declared over-alignment, the compiler may load > llist.next and u_flags as one naturally aligned double word. Fields using > this type, such as task_struct::wake_entry only guarantee pointer alignment, > which faults on strict-alignment 32-bit architectures like hexagon. Where exactly does this happen? I'm failing with grep.