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Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , netdev , linux-mm , Cgroups , LKML Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 4, 2020 at 3:39 PM Shakeel Butt 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 such 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 > --- > Changes since v1: > - added sk->sk_rmem_alloc to initial charging. > - added synchronization to get memory usage and set sk_memcg race-free. > > net/ipv4/inet_connection_sock.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c > index a4db79b1b643..7bcd657cd45e 100644 > --- a/net/ipv4/inet_connection_sock.c > +++ b/net/ipv4/inet_connection_sock.c > @@ -482,6 +482,25 @@ 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) { > + int amt; > + > + /* atomically get the memory usage and set sk->sk_memcg. */ > + lock_sock(newsk); > + > + /* The sk has not been accepted yet, no need to look at > + * sk->sk_wmem_queued. > + */ > + amt = sk_mem_pages(newsk->sk_forward_alloc + > + atomic_read(&sk->sk_rmem_alloc)); > + mem_cgroup_sk_alloc(newsk); > + > + release_sock(newsk); > + > + if (newsk->sk_memcg) Most sockets in accept queue should have amt == 0, so maybe avoid calling this thing only when amt == 0 ? Also I would release_sock(newsk) after this, otherwise incoming packets could mess with newsk->sk_forward_alloc if (amt && newsk->sk_memcg) mem_cgroup_charge_skmem(newsk->sk_memcg, amt); release_sock(newsk); Also, I wonder if mem_cgroup_charge_skmem() has been used at all these last four years on arches with PAGE_SIZE != 4096 ( SK_MEM_QUANTUM is not anymore PAGE_SIZE, but 4096) > + mem_cgroup_charge_skmem(newsk->sk_memcg, amt); > + } > out: > release_sock(sk); > if (req) > -- > 2.25.0.265.gbab2e86ba0-goog >