>> We need to add the count of empty pages to let users know how many empty >> pages are merged with kernel zero page(s). >> >> Please see the subsequent patches for details. > Just raising the topic here because it's related to the KSM usage of the > shared zero-page: > MADV_UNMERGEABLE and other ways to trigger unsharing will *not* unshare > the shared zeropage as placed by KSM (which is against the > MADV_UNMERGEABLE documentation at least). It will only unshare actual > KSM pages. We might not want want to blindly unshare all shared > zeropages in applicable VMAs ... using a dedicated shared zero (KSM) > page -- instead of the generic zero page -- might be one way to handle > this cleaner. > Would that also fix some of the issues you describe above? Glad to see your reply. I think it depends. The way you said solves the issue you post, but maybe not help to solve the issue I post. The key lies in whether appending zeropage's rmap_items to stable tree. If appending their rmap_items to the stable tree, the issue I pointed can be fixed but that will degrade the performance of use_zero_pages. If not appending their rmap_items to the stable tree, we have to choose this patches set (but I found some bugs now, later I will send v2 to fix it).
