From 6bc1a656ab9f57f0112823b4a36930c9a29d1f89 Mon Sep 17 00:00:00 2001 From: Moshe Lazer Date: Thu, 27 Oct 2016 16:36:42 +0300 Subject: [PATCH] IB/mlx5: Resolve soft lock on massive reg MRs 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 --- drivers/infiniband/hw/mlx5/mlx5_ib.h | 2 ++ drivers/infiniband/hw/mlx5/mr.c | 6 +++++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h index dcdcd195fe53..7d689903c87c 100644 --- a/drivers/infiniband/hw/mlx5/mlx5_ib.h +++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h @@ -626,6 +626,8 @@ 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; #ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING struct ib_odp_caps odp_caps; diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c index d4ad672b905b..4e9012463c37 100644 --- a/drivers/infiniband/hw/mlx5/mr.c +++ b/drivers/infiniband/hw/mlx5/mr.c @@ -610,6 +610,7 @@ int mlx5_mr_cache_init(struct mlx5_ib_dev *dev) int err; int i; + mutex_init(&dev->slow_path_mutex); cache->wq = alloc_ordered_workqueue("mkey_cache", WQ_MEM_RECLAIM); if (!cache->wq) { mlx5_ib_warn(dev, "failed to create work queue\n"); @@ -1182,9 +1183,12 @@ struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length, goto error; } - if (!mr) + if (!mr) { + mutex_lock(&dev->slow_path_mutex); mr = reg_create(NULL, pd, virt_addr, length, umem, ncont, page_shift, access_flags); + mutex_unlock(&dev->slow_path_mutex); + } if (IS_ERR(mr)) { err = PTR_ERR(mr); -- GitLab