Messages in this thread | | | Date | Fri, 2 Dec 2011 16:04:08 -0200 | From | Glauber Costa <> | Subject | Re: [PATCH v7 00/10] Request for Inclusion: per-cgroup tcp memory pressure |
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On 11/30/2011 12:11 AM, KAMEZAWA Hiroyuki wrote: > On Tue, 29 Nov 2011 21:56:51 -0200 > Glauber Costa<glommer@parallels.com> 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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