> It like the way you've rearranged isolate_lru_page() there, but I > don't think it amounts to more than a cleanup. Very good thinking > about the odd "lruvec->pgdat = pgdat" case tucked away inside > mem_cgroup_page_lruvec(), but actually, what harm does it do, if > mem_cgroup_move_account() changes page->mem_cgroup concurrently? Maybe the page could be added to root_mem_cgroup? > > You say use-after-free, but we have spin_lock_irq here, and the > struct mem_cgroup (and its lruvecs) cannot be freed until an RCU > grace period expires, which we rely upon in many places, and which > cannot happen until after the spin_unlock_irq. > > And the same applies in the pagevec_lru_move functions, doesn't it? > > I think now is not the time for such cleanups. If this fits well > with Alex's per-lruvec locking (or represents an initial direction > that you think he should follow), fine, but better to let him take it > into his patchset in that case, than change the base unnecessarily > underneath him. > > (It happens to go against my own direction, since it separates the > locking from the determination of lruvec, which I insist must be > kept together; but perhaps that won't be quite the same for Alex.) > It looks like we share the same base. Before this patch, root memcg's lruvc lock could guards !PageLRU and it followings, But now, there are much holes in the wall. :) Thanks Alex
