On 17.01.22 14:31, zhangliang (AG) wrote: > Sure, I will do that :) I'm polishing up / testing the patches and might send something out for discussion shortly. Just a note that on my branch was a version with a wrong condition that should have been fixed now. I am still thinking about PTE mapped THP. For these, we'll always have page_count() > 1, essentially corresponding to the number of still-mapped sub-pages. So if we end up with a R/O mapped part of a THP, we'll always have to COW and cannot reuse ever, although it's really just a single process mapping the THP via PTEs. One approach would be to scan the currently locked page table for entries mapping this same page. If page_count() corresponds to that value, we know that only we are mapping the THP and there are no additional references. That would be a special case if we find an anon THP in do_wp_page(). Hm. -- Thanks, David / dhildenb
