From patchwork Sun Oct 25 22:57:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 290217 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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=no 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 05EB1C4363A for ; Sun, 25 Oct 2020 22:57:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B12AE223BD for ; Sun, 25 Oct 2020 22:57:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603666641; bh=sM+uM5VS2B1Fqls2hg33cvDLXN2vaD1TmjVh59xrVx8=; h=Date:From:To:Subject:List-ID:From; b=DW9ESvgI6aGC1DXsIAVJmShHYD1OX5T5HEcj7uuW38KVGOryx1J+C5FPu17M06DHI S5GDtov9zHi1WKKx0XTilo109KKO8vEeAc0D9mRPIf4GHdKStTJaN5ea0AqW3uIc+3 Z/ZJkr1pPDNkl5U3KeanUjk6Z8rxEubQJY6qQ1rQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1419233AbgJYW5V (ORCPT ); Sun, 25 Oct 2020 18:57:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:47716 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391384AbgJYW5U (ORCPT ); Sun, 25 Oct 2020 18:57:20 -0400 Received: from X1 (nat-ab2241.sltdut.senawave.net [162.218.216.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BD4D1222EC; Sun, 25 Oct 2020 22:57:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603666639; bh=sM+uM5VS2B1Fqls2hg33cvDLXN2vaD1TmjVh59xrVx8=; h=Date:From:To:Subject:From; b=1LbTDP1qKv9vnFFUab8bKJCaRhrhsoDLkkotq1L/rb042pHXkFlGWBMvL8JIQHp7G 4y3mh3clRIhbycuE6o5KSbtmCgIFr9VXWD6fmlK/2IsaH10J+SBlbStXP0HXh06973 HSJyre8Mc38M08hLpIPAzEth9WODUIVCRRTqbnvU= Date: Sun, 25 Oct 2020 15:57:19 -0700 From: akpm@linux-foundation.org To: mm-commits@vger.kernel.org, tj@kernel.org, stable@vger.kernel.org, pmladek@suse.com, qiang.zhang@windriver.com Subject: + kthread_worker-prevent-queuing-delayed-work-from-timer_fn-when-it-is-being-canceled.patch added to -mm tree Message-ID: <20201025225719.4xfmn%akpm@linux-foundation.org> User-Agent: s-nail v14.9.10 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: kthread_worker: prevent queuing delayed work from timer_fn when it is being canceled has been added to the -mm tree. Its filename is kthread_worker-prevent-queuing-delayed-work-from-timer_fn-when-it-is-being-canceled.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/kthread_worker-prevent-queuing-delayed-work-from-timer_fn-when-it-is-being-canceled.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/kthread_worker-prevent-queuing-delayed-work-from-timer_fn-when-it-is-being-canceled.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Zqiang Subject: kthread_worker: prevent queuing delayed work from timer_fn when it is being canceled There is a small race window when a delayed work is being canceled and the work still might be queued from the timer_fn: CPU0 CPU1 kthread_cancel_delayed_work_sync() __kthread_cancel_work_sync() __kthread_cancel_work() work->canceling++; kthread_delayed_work_timer_fn() kthread_insert_work(); BUG: kthread_insert_work() should not get called when work->canceling is set. Link: https://lkml.kernel.org/r/20201014083030.16895-1-qiang.zhang@windriver.com Signed-off-by: Zqiang Reviewed-by: Petr Mladek Acked-by: Tejun Heo Cc: Signed-off-by: Andrew Morton --- kernel/kthread.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/kthread.c~kthread_worker-prevent-queuing-delayed-work-from-timer_fn-when-it-is-being-canceled +++ a/kernel/kthread.c @@ -897,7 +897,8 @@ void kthread_delayed_work_timer_fn(struc /* Move the work from worker->delayed_work_list. */ WARN_ON_ONCE(list_empty(&work->node)); list_del_init(&work->node); - kthread_insert_work(worker, work, &worker->work_list); + if (!work->canceling) + kthread_insert_work(worker, work, &worker->work_list); raw_spin_unlock_irqrestore(&worker->lock, flags); }