From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-x22e.google.com (mail-pb0-x22e.google.com [IPv6:2607:f8b0:400e:c01::22e]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 544362C00BD for ; Fri, 3 May 2013 11:31:49 +1000 (EST) Received: by mail-pb0-f46.google.com with SMTP id rq8so630877pbb.33 for ; Thu, 02 May 2013 18:31:45 -0700 (PDT) Date: Fri, 3 May 2013 11:01:36 +0930 From: Alan Modra To: Eric Dumazet Subject: Re: [PATCH net-next] af_unix: fix a fatal race with bit fields Message-ID: <20130503013136.GN5221@bubble.grove.modra.org> References: <1367370761.11020.22.camel@edumazet-glaptop> <20130501115103.58e40f37@kryten> <1367375060.11020.24.camel@edumazet-glaptop> <20130501035425.GD5221@bubble.grove.modra.org> <1367384672.11020.34.camel@edumazet-glaptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1367384672.11020.34.camel@edumazet-glaptop> Cc: netdev , Ambrose Feinstein , Paul Mackerras , Anton Blanchard , linuxppc-dev@lists.ozlabs.org, David Miller List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Apr 30, 2013 at 10:04:32PM -0700, Eric Dumazet wrote: > These kind of errors are pretty hard to find, its a pity to spend time > on them. Well, yes. From the first comment in gcc PR52080. "For the following testcase we generate a 8 byte RMW cycle on IA64 which causes locking problems in the linux kernel btrfs filesystem." Did someone fix btrfs, but not check other kernel locks? Having now hit the same problem again, have you checked that other kernel locks don't have adjacent bit fields in the same 64-bit word? And comment the struct to ensure someone doesn't optimize those unsigned chars back to bit fields. -- Alan Modra Australia Development Lab, IBM