net: decrement memcg jump label when limit, not usage, is changed
The logic of the current code is that whenever we destroy
a cgroup that had its limit set (set meaning different than
maximum), we should decrement the jump_label counter.
Otherwise we assume it was never incremented.
But what the code actually does is test for RES_USAGE
instead of RES_LIMIT. Usage being different than maximum
is likely to be true most of the time.
The effect of this is that the key must become negative,
and since the jump_label test says:
!!atomic_read(&key->enabled);
we'll have jump_labels still on when no one else is
using this functionality.
Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
index 7fed04f..4997878 100644
--- a/net/ipv4/tcp_memcontrol.c
+++ b/net/ipv4/tcp_memcontrol.c
@@ -108,7 +108,7 @@
tcp = tcp_from_cgproto(cg_proto);
percpu_counter_destroy(&tcp->tcp_sockets_allocated);
- val = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_USAGE);
+ val = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_LIMIT);
if (val != RESOURCE_MAX)
jump_label_dec(&memcg_socket_limit_enabled);