From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753997AbaJMUWn (ORCPT ); Mon, 13 Oct 2014 16:22:43 -0400 Received: from smtp2.it.da.ut.ee ([193.40.5.67]:35667 "EHLO smtp2.it.da.ut.ee" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751546AbaJMUWl (ORCPT ); Mon, 13 Oct 2014 16:22:41 -0400 Date: Mon, 13 Oct 2014 23:22:37 +0300 (EEST) From: mroos@linux.ee To: David Miller cc: Linux Kernel list , cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, linux-mm@kvack.org, sparclinux@vger.kernel.org Subject: Re: unaligned accesses in SLAB etc. In-Reply-To: <20141012.132012.254712930139255731.davem@davemloft.net> Message-ID: References: <20141011.221510.1574777235900788349.davem@davemloft.net> <20141012.132012.254712930139255731.davem@davemloft.net> User-Agent: Alpine 2.11 (LRH 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > From: David Miller > Date: Sat, 11 Oct 2014 22:15:10 -0400 (EDT) > > > > > I'm getting tons of the following on sparc64: > > > > [603965.383447] Kernel unaligned access at TPC[546b58] free_block+0x98/0x1a0 > > [603965.396987] Kernel unaligned access at TPC[546b60] free_block+0xa0/0x1a0 > > [603965.410523] Kernel unaligned access at TPC[546b58] free_block+0x98/0x1a0 > In all of the cases, the address is 4-byte aligned but not 8-byte > aligned. And they are vmalloc addresses. > > Which made me suspect the percpu commit: > > ==================== > commit bf0dea23a9c094ae869a88bb694fbe966671bf6d > Author: Joonsoo Kim > Date: Thu Oct 9 15:26:27 2014 -0700 > > mm/slab: use percpu allocator for cpu cache > ==================== > > And indeed, reverting this commit fixes the problem. I tested Joonsoo Kim's fix and it gets rid of the kernel unaligned access messages, yes. But the instability on UltraSparc II era machines still remains - occassional Bus Errors during kernel compilation, messages like this: sh[11771]: segfault at ffd6a4d1 ip 00000000f7cc5714 (rpc 00000000f7cc562c) sp 00000000ffd69d90 error 30002 in libc-2.19.so[f7c44000+16a000] -- Meelis Roos (mroos@linux.ee)