Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756079AbYCNNKY (ORCPT ); Fri, 14 Mar 2008 09:10:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753494AbYCNNKM (ORCPT ); Fri, 14 Mar 2008 09:10:12 -0400 Received: from brick.kernel.dk ([87.55.233.238]:10080 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753433AbYCNNKL (ORCPT ); Fri, 14 Mar 2008 09:10:11 -0400 Date: Fri, 14 Mar 2008 14:10:07 +0100 From: Jens Axboe To: Christof Schmitt Cc: linux-btrace@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: blktrace/relay/s390: Oops in subbuf_splice_actor Message-ID: <20080314131007.GQ17940@kernel.dk> References: <20080314084337.GA9436@schmichrtp.de.ibm.com> <20080314115802.GK17940@kernel.dk> <20080314130552.GA9352@schmichrtp.de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080314130552.GA9352@schmichrtp.de.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1969 Lines: 46 On Fri, Mar 14 2008, Christof Schmitt wrote: > On Fri, Mar 14, 2008 at 12:58:03PM +0100, Jens Axboe wrote: > > That is indeed a bug, does this work for you? > > > > diff --git a/kernel/relay.c b/kernel/relay.c > > index d080b9d..39d1fa8 100644 > > --- a/kernel/relay.c > > +++ b/kernel/relay.c > > @@ -1066,7 +1066,7 @@ static int subbuf_splice_actor(struct file *in, > > unsigned int flags, > > int *nonpad_ret) > > { > > - unsigned int pidx, poff, total_len, subbuf_pages, ret; > > + unsigned int pidx, poff, total_len, subbuf_pages, nr_pages, ret; > > struct rchan_buf *rbuf = in->private_data; > > unsigned int subbuf_size = rbuf->chan->subbuf_size; > > uint64_t pos = (uint64_t) *ppos; > > @@ -1098,7 +1098,9 @@ static int subbuf_splice_actor(struct file *in, > > pidx = (read_start / PAGE_SIZE) % subbuf_pages; > > poff = read_start & ~PAGE_MASK; > > > > - for (total_len = 0; spd.nr_pages < subbuf_pages; spd.nr_pages++) { > > + nr_pages = min_t(unsigned int, subbuf_pages, PIPE_BUFFERS); > > + > > + for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) { > > unsigned int this_len, this_end, private; > > unsigned int cur_pos = read_start + total_len; > > With the patch, i can run dd and 'blktrace -h traceserver' without the > oops. But the output from blktrace only contains only zeros and no > usable data for blkparse. Using blktrace to write the data directly to > disk, without using the blktrace server works. Is there anything i > should look for to help debugging the problem? We should probably get Tom in the loop, as he is the relay expert. I'll make sure the above patch gets into 2.6.25, as it is definitely a bug that needs fixing. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/