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=-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,URIBL_BLOCKED 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 52A62C4741F for ; Mon, 2 Nov 2020 01:07:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1BECC22272 for ; Mon, 2 Nov 2020 01:07:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604279275; bh=Niqq3HHDaK9hED/6KWIFNkPVh25jJQDmz3J5SXB7FEo=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=y5lftRZEXWQeeUUBedtCj2PfTbJu3/fqO/cvmVoQQFNLujfEKko0iW5+0iWLdfzKG qVsrgZNtK3cFYqCniEG0gqTtnBOu4CQOcDkb3Qn+Zo9bUHf+xEKUqFR967PiJRsrjQ mH7HxdeMM9x3Q0hKywClOgz1yWq//Wqj2WDzFkVo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727552AbgKBBHy (ORCPT ); Sun, 1 Nov 2020 20:07:54 -0500 Received: from mail.kernel.org ([198.145.29.99]:49420 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727335AbgKBBHy (ORCPT ); Sun, 1 Nov 2020 20:07:54 -0500 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 185C622268; Mon, 2 Nov 2020 01:07:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604279274; bh=Niqq3HHDaK9hED/6KWIFNkPVh25jJQDmz3J5SXB7FEo=; h=Date:From:To:Subject:In-Reply-To:From; b=kEPjnqHb6CSGc4mnOA92vk95X5/ZHb/ViGi8ZoU8ae+EmxI0kuEkNMo9efUJlsiTO yEPeJXbJl9BAAuseR05wqkEjdGQgdyY9ShwdyDucNj11jaVGLkF5oJtQvSL4NuUyVd dc/3GLITTstvmJkXNnyGyTcVxjoBYrFym/yFTfUk= Date: Sun, 01 Nov 2020 17:07:53 -0800 From: Andrew Morton To: akpm@linux-foundation.org, linux-mm@kvack.org, mm-commits@vger.kernel.org, pmladek@suse.com, qiang.zhang@windriver.com, stable@vger.kernel.org, tj@kernel.org, torvalds@linux-foundation.org Subject: [patch 10/15] kthread_worker: prevent queuing delayed work from timer_fn when it is being canceled Message-ID: <20201102010753.nF453nOWt%akpm@linux-foundation.org> In-Reply-To: <20201101170656.48abbd5e88375219f868af5e@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org 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); } _