On Fri 17-08-12 11:01:06, Glauber Costa wrote: > On 08/17/2012 11:02 AM, Michal Hocko wrote: > > On Thu 09-08-12 17:01:16, Glauber Costa wrote: > >> We can use jump labels to patch the code in or out when not used. > >> > >> Because the assignment: memcg->kmem_accounted = true is done after the > >> jump labels increment, we guarantee that the root memcg will always be > >> selected until all call sites are patched (see memcg_kmem_enabled). > > > > Not that it would be really important because kmem_accounted goes away And just found out it doesn't go away completely, it just transforms from bool to unsigned log (with flags). The rest still holds... > > in a subsequent patch but I think the wording is a bit misleading here. > > First of all there is no guanratee that kmem_accounted=true is seen > > before atomic_inc(&key->enabled) because there is no memory barrier and > > the lock serves just a leave barrier. But I do not think this is > > important at all because key->enabled is what matters here. Even if > > memcg_kmem_enabled is true we do not consider it if the key is disabled, > > right? > > > > Right. -- 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>