From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753850AbdBOXKx (ORCPT ); Wed, 15 Feb 2017 18:10:53 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:53697 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752577AbdBOXKu (ORCPT ); Wed, 15 Feb 2017 18:10:50 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Eli Cohen" , "Leon Romanovsky" , "Maor Gottlieb" , "Doug Ledford" , "Moshe Lazer" Date: Wed, 15 Feb 2017 22:41:40 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 242/306] IB/mlx5: Resolve soft lock on massive reg MRs In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.40-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Moshe Lazer commit 6bc1a656ab9f57f0112823b4a36930c9a29d1f89 upstream. When calling reg_mr of large MRs (e.g. 4GB) from multiple processes and MR caches can't supply the required amount of MRs the slow-path of MR allocation may be used. In this case we need to serialize the slow-path between the processes to avoid soft lock. Fixes: e126ba97dba9 ('mlx5: Add driver for Mellanox Connect-IB adapters') Signed-off-by: Moshe Lazer Signed-off-by: Maor Gottlieb Reviewed-by: Eli Cohen Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- drivers/infiniband/hw/mlx5/mlx5_ib.h | 2 ++ drivers/infiniband/hw/mlx5/mr.c | 6 +++++- 2 files changed, 7 insertions(+), 1 deletion(-) --- a/drivers/infiniband/hw/mlx5/mlx5_ib.h +++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h @@ -376,6 +376,8 @@ struct mlx5_ib_dev { struct mlx5_ib_resources devr; struct mlx5_mr_cache cache; struct timer_list delay_timer; + /* Prevents soft lock on massive reg MRs */ + struct mutex slow_path_mutex; int fill_delay; }; --- a/drivers/infiniband/hw/mlx5/mr.c +++ b/drivers/infiniband/hw/mlx5/mr.c @@ -554,6 +554,7 @@ int mlx5_mr_cache_init(struct mlx5_ib_de int err; int i; + mutex_init(&dev->slow_path_mutex); cache->wq = create_singlethread_workqueue("mkey_cache"); if (!cache->wq) { mlx5_ib_warn(dev, "failed to create work queue\n"); @@ -909,9 +910,12 @@ struct ib_mr *mlx5_ib_reg_user_mr(struct } } - if (!mr) + if (!mr) { + mutex_lock(&dev->slow_path_mutex); mr = reg_create(pd, virt_addr, length, umem, ncont, page_shift, access_flags); + mutex_unlock(&dev->slow_path_mutex); + } if (IS_ERR(mr)) { err = PTR_ERR(mr);