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 E735EC433FF for ; Mon, 29 Jul 2019 19:52:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B7F2D21655 for ; Mon, 29 Jul 2019 19:52:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564429931; bh=PNDGmWQI7cDkfKFaBd1EUA/CM2aZJfNnIxTpY9WEvi0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MdY7UaPIdhk9Mlbe9wMoeCpBcM1i1Cu+/6QGUaYmvtDBNZzxu1iZ/BIBlMOufSwuv cmaMXexSpcqaWrirHt9if4RNjlmtGok6Q8rlJV8mIJb5tgfl8I/D9lHg+OVs2OtfAp sbn9SDL4QVZOR5hyMC0FwThoCeOZHGMGr3QbdrPU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390413AbfG2TwK (ORCPT ); Mon, 29 Jul 2019 15:52:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:43830 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390633AbfG2TwE (ORCPT ); Mon, 29 Jul 2019 15:52:04 -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 A858121849; Mon, 29 Jul 2019 19:52:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564429923; bh=PNDGmWQI7cDkfKFaBd1EUA/CM2aZJfNnIxTpY9WEvi0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BGiNhD97JLkgxiNweLPOCiZknrrBuESDzPTq+WOMai7McFsTmVkNy2ZEiJgzGRju2 6Wq9kzTcga05vtVz4B8BHZClsJwIdSaEdeyr/Fk+352Ioe8gROBprzipyKrdiQPFY7 kRtxnju8lERx97eU22jEOjqWkakYovNfEsIRiNoM= 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 5.2 139/215] block: init flush rq ref count to 1 Date: Mon, 29 Jul 2019 21:22:15 +0200 Message-Id: <20190729190803.642305760@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190729190739.971253303@linuxfoundation.org> References: <20190729190739.971253303@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 8340f69670d8..5183fca0818a 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -117,6 +117,7 @@ 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