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Diffstat (limited to 'net/ipv4/tcp_memcontrol.c')
-rw-r--r--net/ipv4/tcp_memcontrol.c34
1 files changed, 27 insertions, 7 deletions
diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
index 151703791bb..b6f3583ddfe 100644
--- a/net/ipv4/tcp_memcontrol.c
+++ b/net/ipv4/tcp_memcontrol.c
@@ -74,9 +74,6 @@ void tcp_destroy_cgroup(struct mem_cgroup *memcg)
percpu_counter_destroy(&tcp->tcp_sockets_allocated);
val = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_LIMIT);
-
- if (val != RESOURCE_MAX)
- static_key_slow_dec(&memcg_socket_limit_enabled);
}
EXPORT_SYMBOL(tcp_destroy_cgroup);
@@ -107,10 +104,33 @@ static int tcp_update_limit(struct mem_cgroup *memcg, u64 val)
tcp->tcp_prot_mem[i] = min_t(long, val >> PAGE_SHIFT,
net->ipv4.sysctl_tcp_mem[i]);
- if (val == RESOURCE_MAX && old_lim != RESOURCE_MAX)
- static_key_slow_dec(&memcg_socket_limit_enabled);
- else if (old_lim == RESOURCE_MAX && val != RESOURCE_MAX)
- static_key_slow_inc(&memcg_socket_limit_enabled);
+ if (val == RESOURCE_MAX)
+ clear_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
+ else if (val != RESOURCE_MAX) {
+ /*
+ * The active bit needs to be written after the static_key
+ * update. This is what guarantees that the socket activation
+ * function is the last one to run. See sock_update_memcg() for
+ * details, and note that we don't mark any socket as belonging
+ * to this memcg until that flag is up.
+ *
+ * We need to do this, because static_keys will span multiple
+ * sites, but we can't control their order. If we mark a socket
+ * as accounted, but the accounting functions are not patched in
+ * yet, we'll lose accounting.
+ *
+ * We never race with the readers in sock_update_memcg(),
+ * because when this value change, the code to process it is not
+ * patched in yet.
+ *
+ * The activated bit is used to guarantee that no two writers
+ * will do the update in the same memcg. Without that, we can't
+ * properly shutdown the static key.
+ */
+ if (!test_and_set_bit(MEMCG_SOCK_ACTIVATED, &cg_proto->flags))
+ static_key_slow_inc(&memcg_socket_limit_enabled);
+ set_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
+ }
return 0;
}