On 06/25/2012 10:34 PM, Tejun Heo wrote:
On Mon, Jun 25, 2012 at 06:15:27PM +0400, Glauber Costa wrote:Because the ultimate goal of the kmem tracking in memcg is to track slab pages as well, we can't guarantee that we'll always be able to point a page to a particular process, and migrate the charges along with it - since in the common case, a page will contain data belonging to multiple processes. Because of that, when we destroy a memcg, we only make sure the destruction will succeed by discounting the kmem charges from the user charges when we try to empty the cgroup. Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx> CC: Christoph Lameter <cl@xxxxxxxxx> CC: Pekka Enberg <penberg@xxxxxxxxxxxxxx> CC: Michal Hocko <mhocko@xxxxxxx> CC: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> CC: Johannes Weiner <hannes@xxxxxxxxxxx> CC: Suleiman Souhlal <suleiman@xxxxxxxxxx> --- mm/memcontrol.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a6a440b..bb9b6fe 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -598,6 +598,11 @@ static void disarm_kmem_keys(struct mem_cgroup *memcg) { if (test_bit(KMEM_ACCOUNTED_THIS, &memcg->kmem_accounted)) static_key_slow_dec(&mem_cgroup_kmem_enabled_key); + /* + * This check can't live in kmem destruction function, + * since the charges will outlive the cgroup + */ + BUG_ON(res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0);WARN_ON() please. Misaccounted kernel usually is better than dead kernel.
You're absolutely right, will change. -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
