On Fri, Jun 14, 2019 at 11:34:09AM +0200, Peter Zijlstra wrote: > On Wed, May 08, 2019 at 05:43:33PM +0300, Kirill A. Shutemov wrote: > > > + lookup_page_ext(page)->keyid = keyid; > > + lookup_page_ext(page)->keyid = 0; Also, perhaps paranoid; but do we want something like: static inline void page_set_keyid(struct page *page, int keyid) { /* ensure nothing creeps after changing the keyid */ barrier(); WRITE_ONCE(lookup_page_ext(page)->keyid, keyid); barrier(); /* ensure nothing creeps before changing the keyid */ } And this is very much assuming there is no concurrency through the allocator locks.