From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753793Ab1KBXTY (ORCPT ); Wed, 2 Nov 2011 19:19:24 -0400 Received: from mho-03-ewr.mailhop.org ([204.13.248.66]:58334 "EHLO mho-01-ewr.mailhop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752322Ab1KBXTU (ORCPT ); Wed, 2 Nov 2011 19:19:20 -0400 X-Mail-Handler: MailHop Outbound by DynDNS X-Originating-IP: 98.234.237.12 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/mailhop/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX19dW9pdAlCf5vFMr9zHaMS6 Date: Wed, 2 Nov 2011 16:19:17 -0700 From: Tony Lindgren To: David Miller Cc: eric.dumazet@gmail.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org Subject: Re: [PATCH] net: Add back alignment for size for __alloc_skb Message-ID: <20111102231917.GN31337@atomide.com> References: <4EB1CA4F.3090403@gmail.com> <20111102.190955.1902322759075682192.davem@davemloft.net> <4EB1CEC4.3090909@gmail.com> <20111102.191716.1682282796914825621.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111102.191716.1682282796914825621.davem@davemloft.net> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * David Miller [111102 15:42]: > c> > > The issue is calculation of skb->end, which is based upon calculated > > 'size' variable. > > > > skb->end determines alignment of skb_shared_info, which is where the > > alignment problem is occuring for Tony. > > Right, and SMP_CACHE_BYTES setting should save us in any case. > > For ARM, SMP_CACHE_BYTES seems to be set to L1_CACHE_BYTES which in > turn is set via ARM_L1_CACHE_SHIFT which can be set seemingly to any > value but the defaults are 5 and 6 which should be OK. > > So unless Tony is using a non-standard setting of ARM_L1_CACHE_SHIFT, > this report is a bit mysterious. This is happening at least with omap1_defconfig. In that case we have ARM_L1_CACHE_SHIFT=5. Regards, Tony