Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755675AbXIATG2 (ORCPT ); Sat, 1 Sep 2007 15:06:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756641AbXIATGT (ORCPT ); Sat, 1 Sep 2007 15:06:19 -0400 Received: from li6-103.members.linode.com ([66.160.141.103]:1071 "EHLO smtp.falooley.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753684AbXIATGS (ORCPT ); Sat, 1 Sep 2007 15:06:18 -0400 Date: Sat, 1 Sep 2007 12:06:03 -0700 From: Jason Lunz To: David Woodhouse , Nick Piggin Cc: lkml , jffs-dev@axis.com, Hugh Dickins Subject: [jffs2] [rfc] fix write deadlock regression Message-ID: <20070901190602.GA5926@falooley.org> References: <20070830182354.GA25077@falooley.org> <20070831212636.GB12868@falooley.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070831212636.GB12868@falooley.org> User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2152 Lines: 56 I've bisected the deadlock when many small appends are done on jffs2 down to this commit: commit 6fe6900e1e5b6fa9e5c59aa5061f244fe3f467e2 Author: Nick Piggin Date: Sun May 6 14:49:04 2007 -0700 mm: make read_cache_page synchronous Ensure pages are uptodate after returning from read_cache_page, which allows us to cut out most of the filesystem-internal PageUptodate calls. I didn't have a great look down the call chains, but this appears to fixes 7 possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in block2mtd. All depending on whether the filler is async and/or can return with a !uptodate page. It introduced a wait to read_cache_page, as well as a read_cache_page_async function equivalent to the old read_cache_page without any callers. Switching jffs2_gc_fetch_page to read_cache_page_async for the old behavior makes the deadlocks go away, but maybe reintroduces the use-before-uptodate problem? I don't understand the mm/fs interaction well enough to say. Someone more knowledgable should see if similar deadlock issues may have been introduced for other read_cache_page callers, including the other two in jffs2. Signed-off-by: Jason Lunz --- fs/jffs2/fs.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c index 1d3b7a9..8bc727b 100644 --- a/fs/jffs2/fs.c +++ b/fs/jffs2/fs.c @@ -627,7 +627,7 @@ unsigned char *jffs2_gc_fetch_page(struct jffs2_sb_info *c, struct inode *inode = OFNI_EDONI_2SFFJ(f); struct page *pg; - pg = read_cache_page(inode->i_mapping, offset >> PAGE_CACHE_SHIFT, + pg = read_cache_page_async(inode->i_mapping, offset >> PAGE_CACHE_SHIFT, (void *)jffs2_do_readpage_unlock, inode); if (IS_ERR(pg)) return (void *)pg; - 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/