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[142.68.57.212]) by smtp.gmail.com with ESMTPSA id a14sm14040784qkk.73.2020.03.04.09.30.58 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 04 Mar 2020 09:30:58 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1j9XrF-00013f-UT; Wed, 04 Mar 2020 13:30:57 -0400 Date: Wed, 4 Mar 2020 13:30:57 -0400 From: Jason Gunthorpe To: Leon Romanovsky Cc: Doug Ledford , Artemy Kovalyov , linux-rdma@vger.kernel.org Subject: Re: [PATCH rdma-rc] IB/mlx5: Fix implicit ODP race Message-ID: <20200304173057.GA3963@ziepe.ca> References: <20200227113918.94432-1-leon@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200227113918.94432-1-leon@kernel.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Thu, Feb 27, 2020 at 01:39:18PM +0200, Leon Romanovsky wrote: > From: Artemy Kovalyov > > Following race may occur because of the call_srcu and the placement of > the synchronize_srcu vs the xa_erase. > > CPU0 CPU1 > > mlx5_ib_free_implicit_mr: destroy_unused_implicit_child_mr: > xa_erase(odp_mkeys) > synchronize_srcu() > xa_lock(implicit_children) > if (still in xarray) > atomic_inc() > call_srcu() > xa_unlock(implicit_children) > xa_erase(implicit_children): > xa_lock(implicit_children) > __xa_erase() > xa_unlock(implicit_children) > > flush_workqueue() > [..] > free_implicit_child_mr_rcu: > (via call_srcu) > queue_work() > > WARN_ON(atomic_read()) > [..] > free_implicit_child_mr_work: > (via wq) > free_implicit_child_mr() > mlx5_mr_cache_invalidate() > mlx5_ib_update_xlt() <-- UMR QP fail > atomic_dec() > > The wait_event() solves the race because it blocks until > free_implicit_child_mr_work() completes. > > Fixes: 5256edcb98a1 ("RDMA/mlx5: Rework implicit ODP destroy") > Signed-off-by: Artemy Kovalyov > Reviewed-by: Jason Gunthorpe > Signed-off-by: Leon Romanovsky > --- > drivers/infiniband/hw/mlx5/mlx5_ib.h | 1 + > drivers/infiniband/hw/mlx5/odp.c | 17 +++++++---------- > 2 files changed, 8 insertions(+), 10 deletions(-) Applied to for-rc, thanks Jason