From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Ungerer Subject: Re: rcu alignment warning tripping on m68k Date: Fri, 30 May 2014 11:29:41 +1000 Message-ID: <5387DF05.1020103@uclinux.org> References: <538696A0.5090601@uclinux.org> <20140529141151.21ed6f95@alan.etchedpixels.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from icp-osb-irony-out7.external.iinet.net.au ([203.59.1.224]:43931 "EHLO icp-osb-irony-out7.external.iinet.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751745AbaE3B3l (ORCPT ); Thu, 29 May 2014 21:29:41 -0400 In-Reply-To: <20140529141151.21ed6f95@alan.etchedpixels.co.uk> Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: One Thousand Gnomes Cc: Linux Kernel Development , Linux/m68k On 29/05/14 23:11, One Thousand Gnomes wrote: > On Thu, 29 May 2014 12:08:32 +1000 > Greg Ungerer wrote: > >> Hi All, >> >> Inside kernel/rcy/tree.c in __call_rcu() it does an alignment check on >> the head pointer passed in. This trips on m68k systems, because they only >> need alignment of 32bit quantities to 16bit boundaries. > > __alignof perhaps ? That might do. Change then becomes something like: --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2467,7 +2467,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_ unsigned long flags; struct rcu_data *rdp; - WARN_ON_ONCE((unsigned long)head & 0x3); /* Misaligned rcu_head! */ + WARN_ON_ONCE((unsigned long)head & (__alignof__(head) - 1)); /* Misaligned rcu_head! */ if (debug_rcu_head_queue(head)) { /* Probable double call_rcu(), so leak the callback. */ ACCESS_ONCE(head->func) = rcu_leak_callback; Thanks Greg