(2012/06/25 23:15), 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 mem_cgroup_kmem_enabled).
This guarantees that no mischarges are applied.

Jump label decrement happens when the last reference
count from the memcg dies. This will only happen when
the caches are all dead.

Signed-off-by: Glauber Costa <redacted>
CC: Christoph Lameter <redacted>
CC: Pekka Enberg <redacted>
CC: Michal Hocko <redacted>
CC: Kamezawa Hiroyuki <redacted>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <redacted>

Acked-by: KAMEZAWA Hiroyuki <redacted>

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