On Wed, 2018-01-24 at 19:56 -0800, Dan Williams wrote: > The get_user_pages_longterm() api was recently added as a stop-gap > measure to prevent applications from growing dependencies on the > ability to to pin DAX-mapped filesystem blocks for RDMA indefinitely > with no ongoing coordination with the filesystem. This 'longterm' > pinning is also problematic for the non-DAX VMA case where the core-mm > needs a time bounded way to revoke a pin and manipulate the physical > pages. While existing RDMA applications have already grown the > assumption that they can pin page-cache pages indefinitely, the fact > that we are breaking this assumption for filesystem-dax presents an > opportunity to deprecate the 'indefinite pin' mechanisms and move to a > general interface that supports pin revocation. > > While RDMA may grow an explicit Infiniband-verb for this 'memory > registration with lease' semantic, it seems that this problem is > bigger than just RDMA. At LSF/MM it would be useful to have a > discussion between fs, mm, dax, and RDMA folks about addressing this > problem at the core level. > > Particular people that would be useful to have in attendance are > Michal Hocko, Christoph Hellwig, and Jason Gunthorpe (cc'd). Is on demand paging sufficient as a solution for your use case or do you perhaps need something different? See also https://www.openfabrics.org/images/eventpresos/workshops2013/2013_Workshop_Tues_0930_liss_odp.pdf Thanks, Bart.��.n������g��� �a��� �&ޖ)���)��h���&������梷���� �Ǟ�m������)������^�����������v���O��zf������
