On Thu, Oct 19, 2023 at 12:53 PM Peter Xu <peterx@xxxxxxxxxx> wrote: > > On Thu, Oct 19, 2023 at 05:41:01PM +0200, David Hildenbrand wrote: > > That's not my main point. It can easily become a maintenance burden without > > any real use cases yet that we are willing to support. > > That's why I requested a few times that we can discuss the complexity of > cross-mm support already here, and I'm all ears if I missed something on > the "maintenance burden" part.. > > I started by listing what I think might be different, and we can easily > speedup single-mm with things like "if (ctx->mm != mm)" checks with > e.g. memcg, just like what this patch already did with pgtable depositions. > > We keep saying "maintenance burden" but we refuse to discuss what is that.. > > I'll leave that to Suren and Lokesh to decide. For me the worst case is > one more flag which might be confusing, which is not the end of the world.. > Suren, you may need to work more thoroughly to remove cross-mm implications > if so, just like when renaming REMAP to MOVE. Hi Folks, Sorry, I'm just catching up on all the comments in this thread after a week-long absence. Will be addressing other questions separately but for cross-mm one, I think the best way forward would be for me to split this patch into two with the second one adding cross-mm support. That will clearly show how much additional code that requires and will make it easier for us to decide whether to support it or not. TBH, I don't see the need for an additional flag even if the initial version will be merged without cross-mm support. Once it's added the manpage can mention that starting with a specific Linux version cross-mm is supported, no? Also from my quick read, it sounds like we want to prevent movements of pinned pages regardless of cross-mm support. Is my understanding correct? Thanks, Suren. > > Thanks, > > -- > Peter Xu >
