On 08/21/2012 12:35 PM, Michal Hocko wrote: > On Tue 21-08-12 09:54:30, Michal Hocko wrote: >> E.g. how do you handle charges you left behind? Say you charged some >> pages for stack? > > I got to the last patch and see how you do it. You are relying on > free_accounted_pages directly which doesn't check kmem_accounted and > uses PageUsed bit instead. So this is correct. I guess you are relying > on the life cycle of the object in general so other types of objects > should be safe as well and there shouldn't be any leaks. It is just that > the memcg life time is not bounded now. Will think about that. > Unless you have a better way, I believe any kind of transversal in the free page path is performance detrimental. So the best way is to be explicit and mark a specific callsite as a memcg free. As for the unbounded time, you are correct. However, I believe it is possible to move a lot of the work we do for free (such as freeing the percpu counters and the css_id itself) to an earlier time. Also, if it ever becomes a problem, it is theoretically possible to avoid this, by tracking the kmem pages in a per-memcg list. We would then transverse such list as we do for user pages, and reparent them. The problem is that this is also a bit space inefficient, since we can't reuse any more fields in page_struct for the list_head, so we'd need an external structure. There is a list_head + a pointer per tracked page. -- 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>