On 11/30/2011 12:11 AM, KAMEZAWA Hiroyuki wrote:
On Tue, 29 Nov 2011 21:56:51 -0200
Glauber Costa<glommer@xxxxxxxxxxxxx> wrote:
Hi,
This patchset implements per-cgroup tcp memory pressure controls. It did not change
significantly since last submission: rather, it just merges the comments Kame had.
Most of them are style-related and/or Documentation, but there are two real bugs he
managed to spot (thanks)
Please let me know if there is anything else I should address.
After reading all codes again, I feel some strange. Could you clarify ?
Here.
==
+void sock_update_memcg(struct sock *sk)
+{
+ /* right now a socket spends its whole life in the same cgroup */
+ if (sk->sk_cgrp) {
+ WARN_ON(1);
+ return;
+ }
+ if (static_branch(&memcg_socket_limit_enabled)) {
+ struct mem_cgroup *memcg;
+
+ BUG_ON(!sk->sk_prot->proto_cgroup);
+
+ rcu_read_lock();
+ memcg = mem_cgroup_from_task(current);
+ if (!mem_cgroup_is_root(memcg))
+ sk->sk_cgrp = sk->sk_prot->proto_cgroup(memcg);
+ rcu_read_unlock();
==
sk->sk_cgrp is set to a memcg without any reference count.
Then, no check for preventing rmdir() and freeing memcgroup.
Is there some css_get() or mem_cgroup_get() somewhere ?
There were a css_get in the first version of this patchset. It was
removed, however, because it was deemed anti-intuitive to prevent rmdir,
since we can't know which sockets are blocking it, or do anything about
it. Or did I misunderstand something ?
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