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=-9.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 55796C04FF3 for ; Sat, 22 May 2021 00:55:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2FD8861168 for ; Sat, 22 May 2021 00:55:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230285AbhEVA5K (ORCPT ); Fri, 21 May 2021 20:57:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41984 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230280AbhEVA5J (ORCPT ); Fri, 21 May 2021 20:57:09 -0400 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0DDBC061574; Fri, 21 May 2021 17:55:45 -0700 (PDT) Received: by mail-wr1-x42a.google.com with SMTP id d11so22595077wrw.8; Fri, 21 May 2021 17:55:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=i/GOtIqm3vBucvrsX3tS6msGOS9XSleUkpRlxKUqD2g=; b=M+Mi6AB2pb+oOt0WQZWG30i2xOFUcV0gt4INvkS0RZW/tsw37tCS40ko24eykPiKbo tjRSxQMBeQ7eZYoIq1fEOju+LyWtqXjp5LljBbZZKYiJbthZidGrV0ignzsyEw8Fr4Rh 4YTvZnxvQVNBFV+LjElzvR6b+kmGymWvu5MWd1bGh1ZllheUHBDxd69PpNZcJuncE19I xe+v+1afcJxQ51XGBi6kA+lorFbtu8qrKfVuF0fyZuRZf3my3o+vTdu1FBm99gkmNh4K yV1XRSr/M5bJwo2T44M6nRVC63ayWp5GYNXy+HL/jOdWIUiUqcd1exH+PPyM+6t9CZU5 rhDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=i/GOtIqm3vBucvrsX3tS6msGOS9XSleUkpRlxKUqD2g=; b=mcW3GmebeQgAhSdz0E1whDLvEtsuLI40tasNXn6ZG4tHQhXuPf8teSQTIEANHrA+oH szVsWPo1P0On4KnXmiXuvA/uzuKXTKqsiwKUKmbjQ+pbdCUJEQtVzp+77SenzwLiBfnT DTOR960iUEyunzE+MdUzD8SU0iQh8uHcxVpbmfclWUJx22lnlsC4WU9x4uvqRXfsEkGg WZT9HdzlweM5bko2SlK6LsTFfTqbGVv0u61hMCDNAtN7jdY1pO75eh1wUJOVHVQ+bwef YHl0rrSZPp4Dgo6oJL+DOMR/Aaq/5+ssJBw6YtgSGzuucZr3Yj5ktYuYKx6/podPexxH zo8A== X-Gm-Message-State: AOAM531mYD5y7C/l58p62tJ+/nV+wVUOS/9XKJnKNQ1+q2IviODufnJl hHhTJvr0jWm2vmZ8XN9VEKw= X-Google-Smtp-Source: ABdhPJxlUx6PN+TeZgFX8NVmu3QEZaU92AaeCE17BO1Qek84diFfFougBMPiD4riu61hf0jGbah7fw== X-Received: by 2002:a05:6000:244:: with SMTP id m4mr11884612wrz.225.1621644944518; Fri, 21 May 2021 17:55:44 -0700 (PDT) Received: from [192.168.8.197] ([85.255.236.182]) by smtp.gmail.com with ESMTPSA id a123sm1047247wmd.2.2021.05.21.17.55.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 May 2021 17:55:43 -0700 (PDT) Subject: =?UTF-8?B?UmU6IOWbnuWkjTogW3N5emJvdF0gS0FTQU46IHVzZS1hZnRlci1mcmVl?= =?UTF-8?Q?_Read_in_io=5fworker=5fhandle=5fwork?= To: "Zhang, Qiang" , syzbot , "axboe@kernel.dk" , "io-uring@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "syzkaller-bugs@googlegroups.com" References: <0000000000008224bf05c2a8a78b@google.com> From: Pavel Begunkov Message-ID: Date: Sat, 22 May 2021 01:55:37 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 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: io-uring@vger.kernel.org On 5/21/21 9:45 AM, Zhang, Qiang wrote: [...] > It looks like > thread iou-wrk-28796 in io-wq(A) access wqe in the wait queue(data->hash->wait), but this wqe has been free due to the destruction of another io-wq(B). > > Should we after wait for all iou-wrk thread exit in the io-wq， remove wqe from the waiting queue (data->hash->wait). prevent some one wqe belonging to this io-wq , may be still existing in the (data->hash->wait)queue before releasing. The guess looks reasonable, it's likely a problem. Not sure about the diff, it seems racy but I need to take a closer look to say for sure > look forward to your opinion. > > --- a/fs/io-wq.c > +++ b/fs/io-wq.c > @@ -1003,13 +1003,17 @@ static void io_wq_exit_workers(struct io_wq *wq) > struct io_wqe *wqe = wq->wqes[node]; > > io_wq_for_each_worker(wqe, io_wq_worker_wake, NULL); > - spin_lock_irq(&wq->hash->wait.lock); > - list_del_init(&wq->wqes[node]->wait.entry); > - spin_unlock_irq(&wq->hash->wait.lock); > } > rcu_read_unlock(); > io_worker_ref_put(wq); > wait_for_completion(&wq->worker_done); > + for_each_node(node) { > + struct io_wqe *wqe = wq->wqes[node]; > + > + spin_lock_irq(&wq->hash->wait.lock); > + list_del_init(&wq->wqes[node]->wait.entry); > + spin_unlock_irq(&wq->hash->wait.lock); > + } > put_task_struct(wq->task); > wq->task = NULL; > } -- Pavel Begunkov