On Thu, Mar 06, 2025 at 01:19:41PM -0500, Gregory Price wrote: > On Thu, Mar 06, 2025 at 05:45:34PM +0000, Matthew Wilcox wrote: > > On Thu, Mar 06, 2025 at 12:24:16PM -0500, Gregory Price wrote: > > > we may also need this: > > > https://lore.kernel.org/linux-mm/20250107000346.1338481-4-gourry@xxxxxxxxxx/ > > > > > > May be worth just pulling these ahead to avoid conflict. > > > > Or not putting them in at all because this whole thing is a magnificent > > waste of time? > > Divorced from the tiering mechanisms, is making misplaced migration able > to migrate unmapped pages not generally useful? The only thing I can think of is if you have a process or set of processes on node A calling read() and the file is cached on node B. But in order to decide if the page is on the wrong node, you'd need to track a lot of information about which nodes the page is being accessed from. Which is probably why we've never bothered to do it. This is not a large patch for you to carry as part of your patchset. There's nothing intrinsically wrong with it; it just has no users in mainline and no real prospect of any being added soon.
