On Tue 22-04-14 18:17:09, Jianyu Zhan wrote: > On Tue, Apr 22, 2014 at 5:47 PM, Michal Hocko <mhocko@xxxxxxx> wrote: > > What about > > 3. last_visited == last_node in the tree > > > > __mem_cgroup_iter_next returns NULL and the iterator would return > > without visiting anything. > > Hi, Michal, > > yep, if 3 last_visited == last_node, then this means we have done a round-trip, > thus __mem_cgroup_iter_next returns NULL, in turn mem_cgroup_iter() return NULL. Sorry, I should have been more specific that I was talking about mem_cgroup_reclaim_cookie path where the iteration for this particular zone and priority ended at the last node without finishing the full roundtrip last time. This new iteration (prev==NULL) wants to continue and it should start a new roundtrip. Makes sense? -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>