3.16.40-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Moshe Lazer <[email protected]> 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 <[email protected]> Signed-off-by: Maor Gottlieb <[email protected]> Reviewed-by: Eli Cohen <[email protected]> Signed-off-by: Leon Romanovsky <[email protected]> Signed-off-by: Doug Ledford <[email protected]> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- 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);
