Re: [PATCH] net: memcg: late association of sock to memcg
From: Roman Gushchin <hidden>
Date: 2020-02-22 01:49:36
Also in:
cgroups, linux-mm, lkml
On Fri, Feb 21, 2020 at 05:04:56PM -0800, 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 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 <redacted>
Hello, Shakeel!
quoted hunk ↗ jump to hunk
--- 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)); + }
Looks good for me from the memcg side. Let's see what networking people will say... Btw, do you plan to make a separate patch for associating the socket with the default cgroup on the unified hierarchy? I mean cgroup_sk_alloc(). Thank you for working on it! Roman