Re: [PATCH v6 3/3] mm/gup: disallow FOLL_LONGTERM GUP-fast writing to file-backed mappings
From: Jason Gunthorpe <jgg@nvidia.com>
Date: 2023-05-02 13:51:08
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On Tue, May 02, 2023 at 03:47:43PM +0200, David Hildenbrand wrote:
quoted
Eventually we want to implement a mechanism where we can dynamically pin in response to RPCIT.Okay, so IIRC we'll fail starting the domain early, that's good. And if we pin all guest memory (instead of small pieces dynamically), there is little existing use for file-backed RAM in such zPCI configurations (because memory cannot be reclaimed either way if it's all pinned), so likely there are no real existing users.
Right, this is VFIO, the physical HW can't tolerate not having pinned memory, so something somewhere is always pinning it. Which, again, makes it weird/wrong that this KVM code is pinning it again :\ Jason