On Mon, Oct 23, 2023 at 10:43:49AM -0700, Suren Baghdasaryan wrote: > > Maybe we should follow what it does with mremap()? Then your current code > > is fine. Maybe that's the better start. > > I think that was the original intention, basically treating remapping > as a write operation. Maybe I should add a comment here to make it > more clear? Please avoid mention "emulate as a write" - this is not a write, e.g., we move a swap entry over without faulting in the page. We also keep the page states, e.g. on hotness. A write will change all of that. Now rethinking with the recently merged WP_ASYNC: we ignore uffd-wp, which means dirty from uffd-wp async tracking POV, that matches with soft-dirty always set. Looks all good. Perhaps something like "Follow mremap() behavior; ignore uffd-wp for now" should work? -- Peter Xu
