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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>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.