From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5FFE8C43214 for ; Wed, 1 Sep 2021 09:52:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4ACCD60184 for ; Wed, 1 Sep 2021 09:52:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243777AbhIAJxB (ORCPT ); Wed, 1 Sep 2021 05:53:01 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:59328 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243721AbhIAJxA (ORCPT ); Wed, 1 Sep 2021 05:53:00 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R921e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04420;MF=yun.wang@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0UmvSa8n_1630489922; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UmvSa8n_1630489922) by smtp.aliyun-inc.com(127.0.0.1); Wed, 01 Sep 2021 17:52:02 +0800 Subject: Re: [RFC PATCH] io_uring: stop issue failed request to fix panic To: Pavel Begunkov , Jens Axboe , "open list:IO_URING" , open list References: From: =?UTF-8?B?546L6LSH?= Message-ID: <88c0b5ca-134f-85e5-4e25-b2ea558c4061@linux.alibaba.com> Date: Wed, 1 Sep 2021 17:52:01 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/9/1 δΈ‹εˆ5:47, Pavel Begunkov wrote: > On 9/1/21 10:39 AM, ηŽ‹θ΄‡ wrote: >> We observed panic: >> BUG: kernel NULL pointer dereference, address:0000000000000028 >> [skip] >> Oops: 0000 [#1] SMP PTI >> CPU: 1 PID: 737 Comm: a.out Not tainted 5.14.0+ #58 >> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 >> RIP: 0010:vfs_fadvise+0x1e/0x80 >> [skip] >> Call Trace: >> ? tctx_task_work+0x111/0x2a0 >> io_issue_sqe+0x524/0x1b90 > > Most likely it was fixed yesterday. Can you try? > https://git.kernel.dk/cgit/linux-block/log/?h=for-5.15/io_uring > > Or these two patches in particular > > https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=c6d3d9cbd659de8f2176b4e4721149c88ac096d4 > https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=b8ce1b9d25ccf81e1bbabd45b963ed98b2222df8 Yup, it no longer panic :-) Regards, Michael Wang > >> This is caused by io_wq_submit_work() calling io_issue_sqe() >> on a failed fadvise request, and the io_init_req() return error >> before initialize the file for it, lead into the panic when >> vfs_fadvise() try to access 'req->file'. >> >> This patch add the missing check & handle for failed request >> before calling io_issue_sqe(). >> >> Signed-off-by: Michael Wang >> --- >> fs/io_uring.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index 6f35b12..bfec7bf 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -2214,7 +2214,8 @@ static void io_req_task_submit(struct io_kiocb *req, bool *locked) >> >> io_tw_lock(ctx, locked); >> /* req->task == current here, checking PF_EXITING is safe */ >> - if (likely(!(req->task->flags & PF_EXITING))) >> + if (likely(!(req->task->flags & PF_EXITING) && >> + !(req->flags & REQ_F_FAIL))) >> __io_queue_sqe(req); >> else >> io_req_complete_failed(req, -EFAULT); >> @@ -6704,7 +6705,10 @@ static void io_wq_submit_work(struct io_wq_work *work) >> >> if (!ret) { >> do { >> - ret = io_issue_sqe(req, 0); >> + if (likely(!(req->flags & REQ_F_FAIL))) >> + ret = io_issue_sqe(req, 0); >> + else >> + io_req_complete_failed(req, -EFAULT); >> /* >> * We can get EAGAIN for polled IO even though we're >> * forcing a sync submission from here, since we can't >> >