From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: Re: Corruption with O_DIRECT and unaligned user buffers Date: Fri, 19 Dec 2008 21:27:16 +0100 Message-ID: <20081219202716.GA6383@random.random> References: <491DAF8E.4080506@quantum.com> <200811191526.00036.nickpiggin@yahoo.com.au> <20081119165819.GE19209@random.random> <20081218152952.GW24856@random.random> <20081219161911.dcf15331.kamezawa.hiroyu@jp.fujitsu.com> <494B50C9.7080308@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: KAMEZAWA Hiroyuki , Nick Piggin , Tim LaBerge , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, FNST-Wang Chen To: Li Zefan Return-path: Received: from mx2.redhat.com ([66.187.237.31]:53195 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750757AbYLSU1g (ORCPT ); Fri, 19 Dec 2008 15:27:36 -0500 Content-Disposition: inline In-Reply-To: <494B50C9.7080308@cn.fujitsu.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Hello, On Fri, Dec 19, 2008 at 03:44:09PM +0800, Li Zefan wrote: > Tim LaBerge, though the program can pass but sometimes hanged. strace log is > attached, and we'll test it again with LOCKDEP enabled to see if we can get > some other information. So my current suggestion on this is to understand why __reclaim_stacks is not starting with a lll_unlock before the list_for_each runs, I'll look into this next week if nobody explained it yet ;). Statistically speaking it's more likely to be the kernel patch to be buggy and this is likely a faulty theory I know, but it's not impossible that this is an unrelated bug that was hidden as it required userland list_del/add/splice to race against the kernel ptep_set_wrprotect single instruction.