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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham 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 0BD7DC4361B for ; Fri, 18 Dec 2020 07:27:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D192423A23 for ; Fri, 18 Dec 2020 07:27:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732966AbgLRH1c (ORCPT ); Fri, 18 Dec 2020 02:27:32 -0500 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:56669 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732686AbgLRH1c (ORCPT ); Fri, 18 Dec 2020 02:27:32 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=xiaoguang.wang@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0UJ-.pew_1608276408; Received: from localhost(mailfrom:xiaoguang.wang@linux.alibaba.com fp:SMTPD_---0UJ-.pew_1608276408) by smtp.aliyun-inc.com(127.0.0.1); Fri, 18 Dec 2020 15:26:48 +0800 From: Xiaoguang Wang To: io-uring@vger.kernel.org Cc: axboe@kernel.dk, asml.silence@gmail.com, joseph.qi@linux.alibaba.com Subject: [PATCH] io_uring: fix io_wqe->work_list corruption Date: Fri, 18 Dec 2020 15:26:48 +0800 Message-Id: <20201218072648.9649-1-xiaoguang.wang@linux.alibaba.com> X-Mailer: git-send-email 2.17.2 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org For the first time a req punted to io-wq, we'll initialize io_wq_work's list to be NULL, then insert req to io_wqe->work_list. If this req is not inserted into tail of io_wqe->work_list, this req's io_wq_work list will point to another req's io_wq_work. For splitted bio case, this req maybe inserted to io_wqe->work_list repeatedly, once we insert it to tail of io_wqe->work_list for the second time, now io_wq_work->list->next will be invalid pointer, which then result in many strang error, panic, kernel soft-lockup, rcu stall, etc. In my vm, kernel doest not have commit cc29e1bf0d63f7 ("block: disable iopoll for split bio"), below fio job can reproduce this bug steadily: [global] name=iouring-sqpoll-iopoll-1 ioengine=io_uring iodepth=128 numjobs=1 thread rw=randread direct=1 registerfiles=1 hipri=1 bs=4m size=100M runtime=120 time_based group_reporting randrepeat=0 [device] directory=/home/feiman.wxg/mntpoint/ # an ext4 mount point If we have commit cc29e1bf0d63f7 ("block: disable iopoll for split bio"), there will no splitted bio case for polled io, but I think we still to need to fix this list corruption, it also should maybe go to stable branchs. To fix this corruption, if a req is inserted into tail of io_wqe->work_list, initialize req->io_wq_work->list->next to bu NULL. Signed-off-by: Xiaoguang Wang --- fs/io-wq.h | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/io-wq.h b/fs/io-wq.h index 069496c6d4f9..75113bcd5889 100644 --- a/fs/io-wq.h +++ b/fs/io-wq.h @@ -59,6 +59,7 @@ static inline void wq_list_add_tail(struct io_wq_work_node *node, list->last->next = node; list->last = node; } + node->next = NULL; } static inline void wq_list_cut(struct io_wq_work_list *list, -- 2.17.2