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,USER_AGENT_GIT autolearn=ham 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 EA5DAC35DF9 for ; Thu, 27 Feb 2020 13:55:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B78612469B for ; Thu, 27 Feb 2020 13:55:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582811706; bh=/cgqfmp8nwk5RY90ggAflTwKCmubantpkDVWc3yF89U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Lp1OB0Q6OyhNBeCl0DyxbXepbrL5qofp39KPL6KhWZVFbLI6EkzU5V6Sf8b/RP2kr AE+7z+qCXxBBijTrHxzEjoX76FvULTgcfFfXDHsWCPr2rfV+CAoyVKnn34bgLCjsDC N+e2LoSb1i5QidSvaf0eGFf/fTKzDSGDrRDhhwWg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731634AbgB0NzF (ORCPT ); Thu, 27 Feb 2020 08:55:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:55240 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731488AbgB0NzC (ORCPT ); Thu, 27 Feb 2020 08:55:02 -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 179262469D; Thu, 27 Feb 2020 13:55:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582811701; bh=/cgqfmp8nwk5RY90ggAflTwKCmubantpkDVWc3yF89U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tAlwyptMBKYwB5gqr+U6s6B7f8GkaQGZShVsagr3uvNl8FfQL1mC2GKiXlYSwvaGn djNO2BdT3L+0hjbQJDbZC8+TY0p7Y5EOOylHOrJz8ke4tm7OKTu3dc5On0QS48P+Th pxsdwKgfpMTINF77nx/jWk6Sd7uhedRzrNLm3ruI= 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 4.14 067/237] nbd: add a flush_workqueue in nbd_start_device Date: Thu, 27 Feb 2020 14:34:41 +0100 Message-Id: <20200227132302.000021274@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200227132255.285644406@linuxfoundation.org> References: <20200227132255.285644406@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 4c661ad91e7d3..8f56e6b2f114f 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1203,6 +1203,16 @@ 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