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=-6.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 BC0B2C433E7 for ; Thu, 15 Oct 2020 12:38:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 07BD122269 for ; Thu, 15 Oct 2020 12:38:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="UdiyIu1F" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 07BD122269 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EFE3A6B005D; Thu, 15 Oct 2020 08:38:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EAE97900002; Thu, 15 Oct 2020 08:38:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DEB2E6B0068; Thu, 15 Oct 2020 08:38:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0212.hostedemail.com [216.40.44.212]) by kanga.kvack.org (Postfix) with ESMTP id AAC7E6B005D for ; Thu, 15 Oct 2020 08:38:18 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 329AE181AC9CC for ; Thu, 15 Oct 2020 12:38:18 +0000 (UTC) X-FDA: 77374112676.04.chalk34_0407cfd27214 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id 110138000060 for ; Thu, 15 Oct 2020 12:38:18 +0000 (UTC) X-HE-Tag: chalk34_0407cfd27214 X-Filterd-Recvd-Size: 2325 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf31.hostedemail.com (Postfix) with ESMTP for ; Thu, 15 Oct 2020 12:38:17 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1602765496; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=a+Pa0B5CN/PbWsmHhZzk3whTHIdiCe8IRTsjHXMe2xo=; b=UdiyIu1FGyq1WJCwRWhuWOx+RJ4Pir8gltvaxPcDzm5nBYGP2JVb02i3zl4niJGxBQBZPD 1VTYeqN7ICyjk1QEfaykvLjJbOVBp+38Qu6jUPXUZxbw8JAjaZrwPHEHo+O/ZJFrXnmkzz 8EUeJoYCbvnd2XEKjUvlSCChcR3+iRE= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 693C7B1A0; Thu, 15 Oct 2020 12:38:16 +0000 (UTC) Date: Thu, 15 Oct 2020 14:38:15 +0200 From: Petr Mladek To: akpm@linux-foundation.org Cc: tj@kernel.org, hdanton@sina.com, Zqiang , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v4] kthread_worker: Prevent queuing delayed work from timer_fn when it is being canceled Message-ID: <20201015123815.GE8871@alley> References: <20201014075048.15473-1-qiang.zhang@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201014075048.15473-1-qiang.zhang@windriver.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.001213, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed 2020-10-14 15:50:48, Zqiang wrote: > 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. > > Cc: > Reviewed-by: Petr Mladek > Acked-by: Tejun Heo > Signed-off-by: Zqiang Andrew, are you going to take this patch with -mm tree, please? I think that you usually take the changes in kthread.c. Best Regards, Petr