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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 5422AC35642 for ; Fri, 21 Feb 2020 08:19:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1830724691 for ; Fri, 21 Feb 2020 08:19:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582273182; bh=sgwlTZtHceOcXQlBCBMlRKJUHnRjwhhrQxZY8HOsp7I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=O7MLST8jU2Yr9c618K18UnBSGtbFBgVfwWz1QGvJ0fu7QC+NkokBznpE4t6Kyfzpr EFH6mEOejO3b6WdtseOPKtcrOHSo/SnNZS1QxoOiFYzMPRUrC8qXIToTbKjZop/9if lQV/iZiXShq/efHJoteAS4IkkQcNIJsQSGGadjh4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388054AbgBUITk (ORCPT ); Fri, 21 Feb 2020 03:19:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:58302 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388045AbgBUITi (ORCPT ); Fri, 21 Feb 2020 03:19:38 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 DD96F24694; Fri, 21 Feb 2020 08:19:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582273177; bh=sgwlTZtHceOcXQlBCBMlRKJUHnRjwhhrQxZY8HOsp7I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WUyoQuaPRrrrx+E/0bVXYsPC7P8Nnh1wcFRff0on1UhFOT0mZbNxfFswDcbmIz0GF rU/VqyVl3xiSZ/61ULgQkYbma683eYAOAvZM3I1h97P2jJfn/hw9eJ6oJ9dU14Y6qn cZY1x/O9HHFFjci6EcOCf+BK+rCvst9xy9Qysav8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sun Ke , Jens Axboe , Sasha Levin Subject: [PATCH 4.19 047/191] nbd: add a flush_workqueue in nbd_start_device Date: Fri, 21 Feb 2020 08:40:20 +0100 Message-Id: <20200221072257.378789807@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200221072250.732482588@linuxfoundation.org> References: <20200221072250.732482588@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sun Ke [ Upstream commit 5c0dd228b5fc30a3b732c7ae2657e0161ec7ed80 ] When kzalloc fail, may cause trying to destroy the workqueue from inside the workqueue. If num_connections is m (2 < m), and NO.1 ~ NO.n (1 < n < m) kzalloc are successful. The NO.(n + 1) failed. Then, nbd_start_device will return ENOMEM to nbd_start_device_ioctl, and nbd_start_device_ioctl will return immediately without running flush_workqueue. However, we still have n recv threads. If nbd_release run first, recv threads may have to drop the last config_refs and try to destroy the workqueue from inside the workqueue. To fix it, add a flush_workqueue in nbd_start_device. Fixes: e9e006f5fcf2 ("nbd: fix max number of supported devs") Signed-off-by: Sun Ke Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/nbd.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index b9d321bdaa8a7..226103af30f05 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1216,6 +1216,16 @@ static int nbd_start_device(struct nbd_device *nbd) args = kzalloc(sizeof(*args), GFP_KERNEL); if (!args) { sock_shutdown(nbd); + /* + * If num_connections is m (2 < m), + * and NO.1 ~ NO.n(1 < n < m) kzallocs are successful. + * But NO.(n + 1) failed. We still have n recv threads. + * So, add flush_workqueue here to prevent recv threads + * dropping the last config_refs and trying to destroy + * the workqueue from inside the workqueue. + */ + if (i) + flush_workqueue(nbd->recv_workq); return -ENOMEM; } sk_set_memalloc(config->socks[i]->sock->sk); -- 2.20.1