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=-15.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 F2243C433F5 for ; Wed, 15 Sep 2021 09:45:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC4F16124E for ; Wed, 15 Sep 2021 09:45:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231940AbhIOJqV (ORCPT ); Wed, 15 Sep 2021 05:46:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50622 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231860AbhIOJqT (ORCPT ); Wed, 15 Sep 2021 05:46:19 -0400 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0CCA1C061574 for ; Wed, 15 Sep 2021 02:45:01 -0700 (PDT) Received: by mail-wr1-x433.google.com with SMTP id b6so2828261wrh.10 for ; Wed, 15 Sep 2021 02:45:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=1GKjrebQ6GDqSCyBbuTbQ1fuwG2T3c7dzDkDzDfGqb8=; b=ib8aK1QnQl7M5tzxRJoImUyWG1JqQoU/H1k92+I+Cx04HW+B38H4kvJsGWHp0V/HdK sGCIP7UowaRvcEW5AM7vCK7fGxhuaZ+fUn0Mh9dDqKVUaU9JJMNklex4nk73I5AtX14F Y66fUrlrBCRKUtWmg47nKJV51p9XtjSE/ZRYuk5Fv5HXzHEJ6QKylLubeF2djQRL6xW5 gSXQ0RxBnZeyq4QFdfK+6GuoNNmp0UKAX7BiDUzkFjaUU8L+VgYuxv2OYNc0fzPhBf/R 49JdHvHJCxYJKhqnSiubdBIYyjnJT44joHdbTQURvd/yGebtIhm+mB6LAqIZYKW5Ro0Z UrZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=1GKjrebQ6GDqSCyBbuTbQ1fuwG2T3c7dzDkDzDfGqb8=; b=48JmqYk5jDrMp+GCk54195PYA/ab+ZdYTEUHiXVWZkpueNBDZJ0GfTFxg8JoXGPfXs ZkOA+872WnixjjkXBuzcS0RLaKI2K3ZZCYZETAKOf3w258oj9KA7t3JQBcZVCWw3i0In Z3AQl20ij9Y7gIgnF/qwTXyQxh3k85AdDT2eK58Nbuzh8XxZPFH5TRI2kHZvGmAOISk5 qIo/0xBcGfYq8xd6Kg8rPRw55WutkoL+5dBCPA2dmAVDuDbUkMSJyLY29SuitW/IfHWq 4kFe3y6ua7XH3Wfsje4fLRlmf5UuYIeAXrqAys71EDRycQmKzpA6uSvUiuaJEb+Nv13Q e8CA== X-Gm-Message-State: AOAM5328bIRXwBfVltiiebarvDnD+Nf8fn1/gDwYRKVmgtcDaZsTDHob Zd+hjE2WdgdVQhwhlpoe9+Qc7qoeKh4= X-Google-Smtp-Source: ABdhPJxoZirVDcy53BYTGuVq/54r7tSpzXENokA0NIdbnW1QtsrX6R2pN1M88BO/304qqYJ070TBzQ== X-Received: by 2002:adf:e30d:: with SMTP id b13mr3941428wrj.438.1631699099651; Wed, 15 Sep 2021 02:44:59 -0700 (PDT) Received: from [192.168.8.197] ([185.69.144.239]) by smtp.gmail.com with ESMTPSA id m3sm16936572wrg.45.2021.09.15.02.44.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Sep 2021 02:44:59 -0700 (PDT) Subject: Re: [PATCH 1/2] io_uring: fix tw list mess-up by adding tw while it's already in tw list To: Hao Xu , Jens Axboe Cc: io-uring@vger.kernel.org, Joseph Qi References: <20210912162345.51651-1-haoxu@linux.alibaba.com> <20210912162345.51651-2-haoxu@linux.alibaba.com> From: Pavel Begunkov Message-ID: <6b9d818b-468e-e409-8dc1-9d4bd586635e@gmail.com> Date: Wed, 15 Sep 2021 10:44:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210912162345.51651-2-haoxu@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 9/12/21 5:23 PM, Hao Xu wrote: > For multishot mode, there may be cases like: > io_poll_task_func() > -> add_wait_queue() > async_wake() > ->io_req_task_work_add() > this one mess up the running task_work list > since req->io_task_work.node is in use. > > similar situation for req->io_task_work.fallback_node. > Fix it by set node->next = NULL before we run the tw, so that when we > add req back to the wait queue in middle of tw running, we can safely > re-add it to the tw list. It may get screwed before we get to "node->next = NULL;", -> async_wake() -> io_req_task_work_add() -> async_wake() -> io_req_task_work_add() tctx_task_work() > Fixes: 7cbf1722d5fc ("io_uring: provide FIFO ordering for task_work") > Signed-off-by: Hao Xu > --- > > fs/io_uring.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 30d959416eba..c16f6be3d46b 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -1216,13 +1216,17 @@ static void io_fallback_req_func(struct work_struct *work) > struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx, > fallback_work.work); > struct llist_node *node = llist_del_all(&ctx->fallback_llist); > - struct io_kiocb *req, *tmp; > + struct io_kiocb *req; > bool locked = false; > > percpu_ref_get(&ctx->refs); > - llist_for_each_entry_safe(req, tmp, node, io_task_work.fallback_node) > + req = llist_entry(node, struct io_kiocb, io_task_work.fallback_node); > + while (member_address_is_nonnull(req, io_task_work.fallback_node)) { > + node = req->io_task_work.fallback_node.next; > + req->io_task_work.fallback_node.next = NULL; > req->io_task_work.func(req, &locked); > - > + req = llist_entry(node, struct io_kiocb, io_task_work.fallback_node); > + } > if (locked) { > if (ctx->submit_state.compl_nr) > io_submit_flush_completions(ctx); > @@ -2126,6 +2130,7 @@ static void tctx_task_work(struct callback_head *cb) > locked = mutex_trylock(&ctx->uring_lock); > percpu_ref_get(&ctx->refs); > } > + node->next = NULL; > req->io_task_work.func(req, &locked); > node = next; > } while (node); > -- Pavel Begunkov