tree 255f3c556b2d9411789a95ba80f2d94ad07ee27a
parent 79c4d80b43b8e43684894574a508a871f0c196bf
author Parav Pandit <parav@mellanox.com> 1508132715 +0300
committer Doug Ledford <dledford@redhat.com> 1508343036 -0400

IB/core: Fix use workqueue without WQ_MEM_RECLAIM

The IB/core provides address resolution service and invokes callback
handler when address resolve request completes of requester in worker
thread context.

Such caller might allocate or free memory in callback handler
depending on the completion status to make further progress or to
terminate a connection. Most ULPs resolve route which involves
allocating route entry and path record elements in callback event handler.

It has been noticed that WQ_MEM_RECLAIM flag should not be used for
workers that tend to allocate memory in this [1] thread discussion.

In order to mitigate this situation, WQ_MEM_RECLAIM flag was dropped for
other such WQs in this [2] patch.

Similar problem might arise with address resolution path, though its not
yet noticed. The ib_addr workqueue is not memory reclaim path due to its
nature of invoking callback that might allocate memory or don't free any
memory under memory pressure.

[1] https://www.spinics.net/lists/linux-rdma/msg53239.html
[2] https://www.spinics.net/lists/linux-rdma/msg53416.html

Fixes: f54816261c2b ("IB/addr: Remove deprecated create_singlethread_workqueue")
Fixes: 5fff41e1f89d ("IB/core: Fix race condition in resolving IP to MAC")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>