(2012/04/24 23:22), Frederic Weisbecker wrote: > On Mon, Apr 23, 2012 at 03:25:59PM -0700, David Rientjes wrote: >> On Sun, 22 Apr 2012, Glauber Costa wrote: >> >>> +/* >>> + * Return the kmem_cache we're supposed to use for a slab allocation. >>> + * If we are in interrupt context or otherwise have an allocation that >>> + * can't fail, we return the original cache. >>> + * Otherwise, we will try to use the current memcg's version of the cache. >>> + * >>> + * If the cache does not exist yet, if we are the first user of it, >>> + * we either create it immediately, if possible, or create it asynchronously >>> + * in a workqueue. >>> + * In the latter case, we will let the current allocation go through with >>> + * the original cache. >>> + * >>> + * This function returns with rcu_read_lock() held. >>> + */ >>> +struct kmem_cache *__mem_cgroup_get_kmem_cache(struct kmem_cache *cachep, >>> + gfp_t gfp) >>> +{ >>> + struct mem_cgroup *memcg; >>> + int idx; >>> + >>> + gfp |= cachep->allocflags; >>> + >>> + if ((current->mm == NULL)) >>> + return cachep; >>> + >>> + if (cachep->memcg_params.memcg) >>> + return cachep; >>> + >>> + idx = cachep->memcg_params.id; >>> + VM_BUG_ON(idx == -1); >>> + >>> + memcg = mem_cgroup_from_task(current); >>> + if (!mem_cgroup_kmem_enabled(memcg)) >>> + return cachep; >>> + >>> + if (rcu_access_pointer(memcg->slabs[idx]) == NULL) { >>> + memcg_create_cache_enqueue(memcg, cachep); >>> + return cachep; >>> + } >>> + >>> + return rcu_dereference(memcg->slabs[idx]); >>> +} >>> +EXPORT_SYMBOL(__mem_cgroup_get_kmem_cache); >>> + >>> +void mem_cgroup_remove_child_kmem_cache(struct kmem_cache *cachep, int id) >>> +{ >>> + rcu_assign_pointer(cachep->memcg_params.memcg->slabs[id], NULL); >>> +} >>> + >>> +bool __mem_cgroup_charge_kmem(gfp_t gfp, size_t size) >>> +{ >>> + struct mem_cgroup *memcg; >>> + bool ret = true; >>> + >>> + rcu_read_lock(); >>> + memcg = mem_cgroup_from_task(current); >> >> This seems horribly inconsistent with memcg charging of user memory since >> it charges to p->mm->owner and you're charging to p. So a thread attached >> to a memcg can charge user memory to one memcg while charging slab to >> another memcg? > > Charging to the thread rather than the process seem to me the right behaviour: > you can have two threads of a same process attached to different cgroups. > > Perhaps it is the user memory memcg that needs to be fixed? > There is a problem of OOM-Kill. To free memory by killing process, 'mm' should be released by kill. So, oom-killer just finds a leader of process. Assume A process X consists of thread A, B and A is thread-group-leader. Put thread A into cgroup/Gold thread B into cgroup/Silver. If we do accounting based on threads, we can't do anything at OOM in cgroup/Silver. An idea 'Killing thread-A to kill thread-B'..... breaks isolation. As far as resources used by process, I think accounting should be done per process. It's not tied to thread. About kmem, if we count task_struct, page tables, etc...which can be freed by OOM-Killer i.e. it's allocated for 'process', should be aware of OOM problem. Using mm->owner makes sense to me until someone finds a great idea to handle OOM situation rather than task killing. Thanks, -Kame -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>