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=-9.8 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,USER_AGENT_GIT autolearn=unavailable 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 ECBB9C388F7 for ; Mon, 9 Nov 2020 13:25:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 956FD2076E for ; Mon, 9 Nov 2020 13:25:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604928308; bh=gyY+1DkSLcznU0Olo7s0bJq06DrF5VPZHNTFOnELTBs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=aJvEwmfhJVvJZ/J1ItISTJ0F9M3EYiiqek0Uro8ov/MsfqXel4s5485hNx7uj9dq3 QwcbrqPNbIZfjiqFqbkqsZ4N3nNqvHtrlERoqVJxi3Q9m0+XnW1MkWPNNCBjEOWQXU 6w7MU0z/5kK4tVIZ4E0t1hs7jpHnhOJdpfp9ytz4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732839AbgKINSY (ORCPT ); Mon, 9 Nov 2020 08:18:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:45538 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387721AbgKINSJ (ORCPT ); Mon, 9 Nov 2020 08:18:09 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 A6F31206D8; Mon, 9 Nov 2020 13:18:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604927888; bh=gyY+1DkSLcznU0Olo7s0bJq06DrF5VPZHNTFOnELTBs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O3xo8o+nNYlWfnw6eaXgwlpu2MJcL5r6ysFtBnfKy7J8t1e+6oU8A3HvW3TH/b9Uu yIr+N4jG6ET7XJUH9AKS+l/cVE2ceGsOROwjnpccWLkFaUI3sPCCe43XzRqsa7zBzK xYpXfmPVX7vZz8hEJ3ZNtkfsnN19SnDhffOE4l3g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zqiang , Andrew Morton , Petr Mladek , Tejun Heo , Linus Torvalds Subject: [PATCH 5.9 055/133] kthread_worker: prevent queuing delayed work from timer_fn when it is being canceled Date: Mon, 9 Nov 2020 13:55:17 +0100 Message-Id: <20201109125033.368511167@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125030.706496283@linuxfoundation.org> References: <20201109125030.706496283@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zqiang commit 6993d0fdbee0eb38bfac350aa016f65ad11ed3b1 upstream. 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. Signed-off-by: Zqiang Signed-off-by: Andrew Morton Reviewed-by: Petr Mladek Acked-by: Tejun Heo Cc: Link: https://lkml.kernel.org/r/20201014083030.16895-1-qiang.zhang@windriver.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/kthread.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/kthread.c +++ b/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); }