On Mon, 20 Apr 2020 18:11:26 -0400 Johannes Weiner wrote: > > The previous patches have simplified the access rules around > page->mem_cgroup somewhat: > > 1. We never change page->mem_cgroup while the page is isolated by > somebody else. This was by far the biggest exception to our rules > and it didn't stop at lock_page() or lock_page_memcg(). > > 2. We charge pages before they get put into page tables now, so the > somewhat fishy rule about "can be in page table as long as it's > still locked" is now gone and boiled down to having an exclusive > reference to the page. > > Document the new rules. Any of the following will stabilize the > page->mem_cgroup association: > > - the page lock > - LRU isolation > - lock_page_memcg() > - exclusive access to the page Then rule-1 makes rule-3 no longer needed in mem_cgroup_move_account()?
