On Thu, Jan 25, 2018 at 12:03:02PM -0500, David Miller wrote:
> From: Roman Gushchin <g...@fb.com>
> Date: Thu, 25 Jan 2018 00:19:11 +0000
>
> > @@ -476,6 +477,10 @@ struct sock *inet_csk_accept(struct sock *sk, int
> > flags, int *err, bool kern)
> > spin_unlock_bh(&queue->fastopenq.lock);
> > }
> > mem_cgroup_sk_alloc(newsk);
> > + amt = sk_memory_allocated(newsk);
> > + if (amt && newsk->sk_memcg)
> > + mem_cgroup_charge_skmem(newsk->sk_memcg, amt);
> > +
>
> This looks confusing to me.
>
> sk_memory_allocated() is the total amount of memory used by all
> sockets for a particular "struct proto", not just for that specific
> socket.
>
> Maybe I don't understand how this socket memcg stuff works, but it
> seems like you should be looking instead at how much memory is
> allocated to this specific socket.
So, the patch below takes the per-socket charge into account,
and it _almost_ works: css leak is weaker by a couple orders
of magnitude, but still exists. I believe, the problem is
that we need additional synchronization for sk_memcg and
sk_forward_alloc fields; and I'm really out of ideas how
to do it without heavy artillery like introducing a new
field for unaccounted memcg charge. As I can see, we
check the sk_memcg field without socket lock; and we
do set it from a concurrent context.
Most likely, I do miss something...
So I really start thinking that reverting 9f1c2674b328
("net: memcontrol: defer call to mem_cgroup_sk_alloc()")
and fixing the original issue differently might be easier
and a proper way to go. Does it makes sense?
Thanks!
--
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 4ca46dc08e63..287de1501a30 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -476,6 +476,12 @@ struct sock *inet_csk_accept(struct sock *sk, int flags,
int *err, bool kern)
spin_unlock_bh(&queue->fastopenq.lock);
}
mem_cgroup_sk_alloc(newsk);
+ if (mem_cgroup_sockets_enabled && newsk->sk_memcg) {
+ int amt = sk_mem_pages(newsk->sk_forward_alloc);
+ if (amt > 0)
+ mem_cgroup_charge_skmem(newsk->sk_memcg, amt);
+ }
+
out:
release_sock(sk);
if (req)
