From: Andreas Dilger Subject: Re: [PATCH][RFC]JBD2: Fix journal checksum kernel oops on NUMA Date: Fri, 2 Nov 2007 13:20:31 +0800 Message-ID: <20071102052031.GC18505@webber.adilger.int> References: <46D7097F.4020501@linux.vnet.ibm.com> <1188552066.3781.15.camel@dhcp5.linsyssoft.com> <1193964035.4014.23.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Girish Shilamkar , Avantika Mathur , linux-ext4@vger.kernel.org To: Mingming Cao Return-path: Received: from mail.clusterfs.com ([74.0.229.162]:51622 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751694AbXKBFVr (ORCPT ); Fri, 2 Nov 2007 01:21:47 -0400 Content-Disposition: inline In-Reply-To: <1193964035.4014.23.camel@localhost.localdomain> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Nov 01, 2007 17:40 -0700, Mingming Cao wrote: > Current journal checksumming patch failed fsstress test on NUMA. The > bh->b_data passed to the crc32_be () function could be NULL pointer, > which caused kernel oops immediately when running fsstress with -o > journal_checksum. It is because the page is part of highmem on NUMA box. > We need to kmap the page before access the bh->b_data to calculate > the checksums. I have no objection to the patch, per-se, but I'm surprised that there would ever be a buffer head pointing at a page in high memory? That seems contrary to what I would expect... Cheers, Andreas -- Andreas Dilger Sr. Software Engineer, Lustre Group Sun Microsystems of Canada, Inc.