tree c6ef3751498db84ff219e13746c548b001037f70
parent e876ecc67db80dfdb8e237f71e5b43bb88ae549c
author Shakeel Butt <shakeelb@google.com> 1583817366 -0700
committer David S. Miller <davem@davemloft.net> 1583879585 -0700

net: memcg: late association of sock to memcg

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 association of the sockets at the accept()
time in the process context and then force charge the memory buffer
already used and reserved by the socket.

Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>