[Devel] [PATCH RH8 2/4] Revert "net/mm/packet: Pre-account maximum socket buffer into cg memory (v3)"

[Vasily Averin]

This reverts commit 850c3f41dcf3eba2f0ffb3b3dd1622c4f647473a.
Current version of af_packet accounting is incorrect
and should be re-implemented later.

https://jira.sw.ru/browse/PSBM-120694
Signed-off-by: Vasily Averin <vvs at virtuozzo.com>
---
 net/packet/af_packet.c | 84 +-----------------------------------------
 1 file changed, 1 insertion(+), 83 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 001a1320ce98..f4bd19532550 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2973,76 +2973,6 @@ static int packet_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 		return packet_snd(sock, msg, len);
 }
 
-#ifdef CONFIG_MEMCG
-struct packet_sk_charge {
-	struct mem_cgroup	*memcg;
-	unsigned long		nr_pages;
-};
-
-static struct mem_cgroup *packet_sk_charge(void)
-{
-	struct packet_sk_charge *psc;
-	int err = -ENOMEM;
-
-	psc = kmalloc(sizeof(*psc), GFP_KERNEL);
-	if (!psc)
-		goto out;
-
-	err = 0;
-	psc->memcg = get_mem_cgroup_from_mm(current->mm);
-	if (psc->memcg == root_mem_cgroup)
-		goto out_free_psc;
-	if (!memcg_kmem_enabled())
-		goto out_put_cg;
-
-	/*
-	 * Forcedly charge the maximum amount of data this socket may have.
-	 * It's typically not huge and packet sockets are rare guests in
-	 * containers, so we don't disturb the memory consumption much.
-	 */
-	psc->nr_pages = READ_ONCE(sysctl_rmem_max)/PAGE_SIZE;
-
-	err = memcg_charge_kmem(psc->memcg, GFP_KERNEL, psc->nr_pages);
-	if (!err)
-		goto out;
-
-out_put_cg:
-	css_put(&psc->memcg->css);
-out_free_psc:
-	kfree(psc);
-	psc = NULL;
-out:
-	if (err)
-		return ERR_PTR(err);
-
-	/*
-	 * The sk->sk_cgrp is not used for packet sockets,
-	 * so we'll just put the smaller structure into it.
-	 */
-	return (struct mem_cgroup *)psc;
-}
-
-static void packet_sk_uncharge(struct mem_cgroup *cg)
-{
-	struct packet_sk_charge *psc = (struct packet_sk_charge *)cg;
-
-	if (psc) {
-		memcg_uncharge_kmem(psc->memcg, psc->nr_pages);
-		css_put(&psc->memcg->css);
-		kfree(psc);
-	}
-}
-#else
-static struct mem_cgroup *packet_sk_charge(void)
-{
-	return NULL;
-}
-
-static void packet_sk_uncharge(struct mem_cgroup *cg)
-{
-}
-#endif
-
 /*
  *	Close a PACKET socket. This is fairly simple. We immediately go
  *	to 'closed' state and remove our protocol entry in the device list.
@@ -3095,8 +3025,6 @@ static int packet_release(struct socket *sock)
 	release_sock(sk);
 
 	f = fanout_release(sk);
-	packet_sk_uncharge(sk->sk_memcg);
-	sk->sk_memcg = NULL;
 
 	synchronize_net();
 
@@ -3276,7 +3204,6 @@ static int packet_create(struct net *net, struct socket *sock, int protocol,
 {
 	struct sock *sk;
 	struct packet_sock *po;
-	struct mem_cgroup *cg;
 	__be16 proto = (__force __be16)protocol; /* weird, but documented */
 	int err;
 
@@ -3287,16 +3214,11 @@ static int packet_create(struct net *net, struct socket *sock, int protocol,
 		return -ESOCKTNOSUPPORT;
 
 	sock->state = SS_UNCONNECTED;
-	cg = packet_sk_charge();
-	if (IS_ERR(cg)) {
-		err = PTR_ERR(cg);
-		goto out;
-	}
 
 	err = -ENOBUFS;
 	sk = sk_alloc(net, PF_PACKET, GFP_KERNEL, &packet_proto, kern);
 	if (sk == NULL)
-		goto outu;
+		goto out;
 
 	sock->ops = &packet_ops;
 	if (sock->type == SOCK_PACKET)
@@ -3345,13 +3267,9 @@ static int packet_create(struct net *net, struct socket *sock, int protocol,
 	sock_prot_inuse_add(net, &packet_proto, 1);
 	preempt_enable();
 
-	sk->sk_memcg = cg;
-
 	return 0;
 out2:
 	sk_free(sk);
-outu:
-	packet_sk_uncharge(cg);
 out:
 	return err;
 }
-- 
2.25.1