Messages in this thread | | | From | Eric Dumazet <> | Date | Sun, 23 Feb 2020 23:29:04 -0800 | Subject | Re: [PATCH] net: memcg: late association of sock to memcg |
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On Fri, Feb 21, 2020 at 5:05 PM Shakeel Butt <shakeelb@google.com> wrote: > > If a TCP socket is allocated in IRQ context or cloned from unassociated > (i.e. not associated to a memcg) in IRQ context then it will remain > unassociated for its whole life. Almost half of the TCPs created on the > system are created in IRQ context, so, memory used by suck sockets will > not be accounted by the memcg. > > This issue is more widespread in cgroup v1 where network memory > accounting is opt-in but it can happen in cgroup v2 if the source socket > for the cloning was created in root memcg. > > To fix the issue, just do the late association of the unassociated > sockets at accept() time in the process context and then force charge > the memory buffer already reserved by the socket. > > Signed-off-by: Shakeel Butt <shakeelb@google.com> > --- > net/ipv4/inet_connection_sock.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c > index a4db79b1b643..df9c8ef024a2 100644 > --- a/net/ipv4/inet_connection_sock.c > +++ b/net/ipv4/inet_connection_sock.c > @@ -482,6 +482,13 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern) > } > spin_unlock_bh(&queue->fastopenq.lock); > } > + > + if (mem_cgroup_sockets_enabled && !newsk->sk_memcg) { > + mem_cgroup_sk_alloc(newsk); > + if (newsk->sk_memcg) > + mem_cgroup_charge_skmem(newsk->sk_memcg, > + sk_mem_pages(newsk->sk_forward_alloc));
I am not sure what you are trying to do here.
sk->sk_forward_alloc is not the total amount of memory used by a TCP socket. It is only some part that has been reserved, but not yet consumed.
For example, every skb that has been stored in TCP receive queue or out-of-order queue might have used memory.
I guess that if we assume that a not yet accepted socket can not have any outstanding data in its transmit queue, you need to use sk->sk_rmem_alloc as well.
To test this patch, make sure to add a delay before accept(), so that 2MB worth of data can be queued before accept() happens.
Thanks.
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