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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 00EE9C38A2F for ; Sat, 18 Apr 2020 14:55:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D6325206D6 for ; Sat, 18 Apr 2020 14:55:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587221734; bh=/wjEcidzZHShNwnxxS64gx2IXXTX7QTd31cbCKTc5lE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=fjgEn3Ht3yiU00CQSiPer0BRG5ty80nnZkGbMOuT+qpSaXt9qqEOBQhalSI7RKUak LDE09S3mJc3YLiqsVDt6pPXRcpITIiGMrUkKnNFX9OhQ6MmnRUkXNchvJDawO2AM/g BWCyRBKJ42A7j67JSNuyf1i1294v82NN028xUnZs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727823AbgDROza (ORCPT ); Sat, 18 Apr 2020 10:55:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:50050 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727797AbgDROlM (ORCPT ); Sat, 18 Apr 2020 10:41:12 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5D8B322202; Sat, 18 Apr 2020 14:41:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587220872; bh=/wjEcidzZHShNwnxxS64gx2IXXTX7QTd31cbCKTc5lE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WGnBdYe4N/gXHlmX+rBqJggDMbqg06LDWKF/+bpLT73TpjwwXmITs+kW+dQKGRMUM BzTJ+vjCw4EPsP2neJPVRBPCYVcI5iGXTejscxdZQ7nBO+Iw5uj5iEM26cEi9+11qu bY8zo23upw13CxuJy/Aan376Jv2gS19fYWpGwcdk= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sagi Grimberg , Keith Busch , Hannes Reinecke , Christoph Hellwig , Sasha Levin , linux-nvme@lists.infradead.org Subject: [PATCH AUTOSEL 5.4 20/78] nvme: fix deadlock caused by ANA update wrong locking Date: Sat, 18 Apr 2020 10:39:49 -0400 Message-Id: <20200418144047.9013-20-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200418144047.9013-1-sashal@kernel.org> References: <20200418144047.9013-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sagi Grimberg [ Upstream commit 657f1975e9d9c880fa13030e88ba6cc84964f1db ] The deadlock combines 4 flows in parallel: - ns scanning (triggered from reconnect) - request timeout - ANA update (triggered from reconnect) - I/O coming into the mpath device (1) ns scanning triggers disk revalidation -> update disk info -> freeze queue -> but blocked, due to (2) (2) timeout handler reference the g_usage_counter - > but blocks in the transport .timeout() handler, due to (3) (3) the transport timeout handler (indirectly) calls nvme_stop_queue() -> which takes the (down_read) namespaces_rwsem - > but blocks, due to (4) (4) ANA update takes the (down_write) namespaces_rwsem -> calls nvme_mpath_set_live() -> which synchronize the ns_head srcu (see commit 504db087aacc) -> but blocks, due to (5) (5) I/O came into nvme_mpath_make_request -> took srcu_read_lock -> direct_make_request > blk_queue_enter -> but blocked, due to (1) ==> the request queue is under freeze -> deadlock. The fix is making ANA update take a read lock as the namespaces list is not manipulated, it is just the ns and ns->head that are being updated (which is protected with the ns->head lock). Fixes: 0d0b660f214dc ("nvme: add ANA support") Signed-off-by: Sagi Grimberg Reviewed-by: Keith Busch Reviewed-by: Hannes Reinecke Signed-off-by: Christoph Hellwig Signed-off-by: Sasha Levin --- drivers/nvme/host/multipath.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index aed6354cb2717..56caddeabb5e5 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -510,7 +510,7 @@ static int nvme_update_ana_state(struct nvme_ctrl *ctrl, if (!nr_nsids) return 0; - down_write(&ctrl->namespaces_rwsem); + down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) { unsigned nsid = le32_to_cpu(desc->nsids[n]); @@ -521,7 +521,7 @@ static int nvme_update_ana_state(struct nvme_ctrl *ctrl, if (++n == nr_nsids) break; } - up_write(&ctrl->namespaces_rwsem); + up_read(&ctrl->namespaces_rwsem); return 0; } -- 2.20.1