Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263827AbTHVPgG (ORCPT ); Fri, 22 Aug 2003 11:36:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263841AbTHVPgG (ORCPT ); Fri, 22 Aug 2003 11:36:06 -0400 Received: from birosca.ime.usp.br ([143.107.45.59]:34246 "HELO birosca.ime.usp.br") by vger.kernel.org with SMTP id S263827AbTHVPgA (ORCPT ); Fri, 22 Aug 2003 11:36:00 -0400 Date: Fri, 22 Aug 2003 12:35:01 -0300 From: Livio Baldini Soares To: Yoav Weiss Cc: linux-kernel@vger.kernel.org Subject: Re: Bug in drivers/block/ll_rw_blk.c ? Message-ID: <20030822153501.GB31360@ime.usp.br> Mail-Followup-To: Livio Baldini Soares , Yoav Weiss , linux-kernel@vger.kernel.org References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.28i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2304 Lines: 67 Hi Yoav! Yoav Weiss writes: > A few days ago I posted the report attached below. After some more > research, I'm starting to think I've hit a bug in ll_rw_blk.c. > > If the maintainer of the block dev subsystem happens to be reading > this, please contact me on the list or by mail. I'm not the maintainer, but I'm pretty sure that there is no problem in that specific code... but I think you're hitting another bug in the 2.4 tree (read below...) [...snip...] > The cloop (compressed loop) code I'm debugging is this one: > > http://developer.linuxtag.net/knoppix/sources/cloop_1.0-2.tar.gz > > I'm testing with kernel 2.4.22-rc2. [...snip...] > The stalled process waits on a page in mm/filemap.c:1505: > > /* Again, try some read-ahead while waiting for the page to finish.. */ > generic_file_readahead(reada_ok, filp, inode, page); > ------> wait_on_page(page); > > > I found who wakes it up in calls that don't stall: > unlock_page(), called from > drivers/block/ll_rw_blk.c:end_that_request_first(). > bh->b_end_io(bh, uptodate) seems to do it. From this description it seems that you are hitting a bug which was discussed to death here on the list. Here's a thread with 143 messages for you: http://marc.theaimsgroup.com/?t=105400721000001&r=5&w=2 And here are the threads in which a solution was dicussed: http://marc.theaimsgroup.com/?t=105519528200001&r=1&w=2 http://marc.theaimsgroup.com/?t=105769525800005&r=3&w=2 Notice, however, that the patch Chris, Andrea, Jens and others made for this problem is _already_ included in 2.4 (so, yes, 2.4.22-rc2 has the fix). So, you are probably hitting the same bug, which was not fixed 100%. If you think that your test is very easily reproducible and can shed more light on this problem, perhaps you should write to Chris, Andrea and Jens (with Cc: to the list), and show them the test. I don't know if they would be willing to spend more time on this issue, specially with 2.6 around the corner... best regards, -- Livio B. Soares - 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/