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=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 D4F64C76186 for ; Mon, 29 Jul 2019 20:04:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A31CF20657 for ; Mon, 29 Jul 2019 20:04:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564430684; bh=7u/+GiX78diQlZSnpnqu2l4eIo9WSrQyRAj9zKhIdHc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=LtKog9QWdbusO/eur1bopyOmYFw0fnMi87Z67q4UBOOFHX7ZWfTCUhp5aOCdLdkDK hr9shmStnu7Ij81E44fqcrn0sQ1U0/ONNvXsVnOCUfed+xHhcohpNUMlGr5oNUBih2 +8Z64iKOrk1iEgKX6KmpsNGl8rtCzMihYqc6Xmhg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389857AbfG2Toy (ORCPT ); Mon, 29 Jul 2019 15:44:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:33404 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389834AbfG2Tor (ORCPT ); Mon, 29 Jul 2019 15:44:47 -0400 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 33CC9205F4; Mon, 29 Jul 2019 19:44:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564429486; bh=7u/+GiX78diQlZSnpnqu2l4eIo9WSrQyRAj9zKhIdHc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SeKB2/yFnql9PaOl0mnQI4OND7DqE6/OJcojsjny+oh+lZrlaG1mlNQRQw+fHsKD9 9igqOcC3kZWjqyGM6QcDiu+WVlNfTiXrIkaeWoJhc5DvnRDTz5p8JXi4O49lB/3CSx 6oJnq+m7Idqvu+FGP+3qZD7gsFwexRvNuD9BARPs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josef Bacik , Jens Axboe , Sasha Levin Subject: [PATCH 4.19 076/113] block: init flush rq ref count to 1 Date: Mon, 29 Jul 2019 21:22:43 +0200 Message-Id: <20190729190713.719362728@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190729190655.455345569@linuxfoundation.org> References: <20190729190655.455345569@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 [ Upstream commit b554db147feea39617b533ab6bca247c91c6198a ] We discovered a problem in newer kernels where a disconnect of a NBD device while the flush request was pending would result in a hang. This is because the blk mq timeout handler does if (!refcount_inc_not_zero(&rq->ref)) return true; to determine if it's ok to run the timeout handler for the request. Flush_rq's don't have a ref count set, so we'd skip running the timeout handler for this request and it would just sit there in limbo forever. Fix this by always setting the refcount of any request going through blk_init_rq() to 1. I tested this with a nbd-server that dropped flush requests to verify that it hung, and then tested with this patch to verify I got the timeout as expected and the error handling kicked in. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/block/blk-core.c b/block/blk-core.c index 682bc561b77b..9ca703bcfe3b 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -198,6 +198,7 @@ void blk_rq_init(struct request_queue *q, struct request *rq) rq->internal_tag = -1; rq->start_time_ns = ktime_get_ns(); rq->part = NULL; + refcount_set(&rq->ref, 1); } EXPORT_SYMBOL(blk_rq_init); -- 2.20.1