From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262336AbTJIRiw (ORCPT ); Thu, 9 Oct 2003 13:38:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262345AbTJIRiw (ORCPT ); Thu, 9 Oct 2003 13:38:52 -0400 Received: from fw.osdl.org ([65.172.181.6]:24235 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S262336AbTJIRiu (ORCPT ); Thu, 9 Oct 2003 13:38:50 -0400 Subject: Re: 2.6.0-test6-mm4 - oops in __aio_run_iocbs() From: Daniel McNeil To: Suparna Bhattacharya Cc: Andrew Morton , Linux Kernel Mailing List , "linux-aio@kvack.org" In-Reply-To: <20031009111624.GA11549@in.ibm.com> References: <20031005013326.3c103538.akpm@osdl.org> <1065655095.1842.34.camel@ibm-c.pdx.osdl.net> <20031009111624.GA11549@in.ibm.com> Content-Type: text/plain Organization: Message-Id: <1065721121.1821.16.camel@ibm-c.pdx.osdl.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.2 (1.2.2-5) Date: 09 Oct 2003 10:38:41 -0700 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2003-10-09 at 04:16, Suparna Bhattacharya wrote: > On Wed, Oct 08, 2003 at 04:18:15PM -0700, Daniel McNeil wrote: > > I'm been testing AIO on test6-mm4 using a ext3 file system and > > copying a 88MB file to an already existing preallocated file of 88MB. > > I been using my aiocp program to copy the file using i/o sizes of > > 1k to 512k and outstanding aio requests of between 1 and 64 using > > O_DIRECT, O_SYNC and O_DIRECT & O_SYNC. Everything works as long > > as the file is pre-allocated. When copying the file to a new file > > (O_CREAT|O_DIRECT), I get the following oops: > > What are the i/o sizes and block sizes for which you get the oops ? > Is this only for large i/o sizes ? I've done more testing and it is a little confusing. I originally got the oops running a shell script which copied 4 88MB files one at a time to a sub-directory: for i in fff ff1 ff2 ff3 do aiocp -b 128k -n 8 -f CREAT -f DIRECT $i junkdir/$i done sync This script would always cause the oops and the machine would lock up. I ran aiocp manually using different block sizes (4k-128k) to copy 1 file to a subdirectory. I removed the file in the subdirectory afterward. These tests completed without any problems or oopses. > __aio_run_iocbs should have been called only for buffered i/o, > so this sounds like an O_DIRECT fallback to buffered i/o. > Possibly after already submitting some blocks direct to BIO, > the i/o completion path for which ends up calling aio_complete > releasing the iocb. That could explain the use-after-free situation > you see. mm4 has my extra iocb ref count for retries patch. So the iocb should not be being freed by aio_complete. The stack trace looks like the fault is on the ctx or ctx->runlist. > > But, O_DIRECT write should fallback to buffered i/o only if it > encounters holes in the middle of the file, not for simple appends > as in your case. Need to figure out how this could have happened ... > > Could you try placing a few printks to find out if this is > the case or if we need to look elsewhere ? I'll do more debugging and let you know what I find. Daniel