[PATCH v6 02/16] memcg: enable accounting for IP address and routing-related objects

From: Vasily Averin <hidden>
Date: 2021-07-26 19:00:16
Also in: lkml, netdev

An netadmin inside container can use 'ip a a' and 'ip r a'
to assign a large number of ipv4/ipv6 addresses and routing entries
and force kernel to allocate megabytes of unaccounted memory
for long-lived per-netdevice related kernel objects:
'struct in_ifaddr', 'struct inet6_ifaddr', 'struct fib6_node',
'struct rt6_info', 'struct fib_rules' and ip_fib caches.

These objects can be manually removed, though usually they lives
in memory till destroy of its net namespace.

It makes sense to account for them to restrict the host's memory
consumption from inside the memcg-limited container.

One of such objects is the 'struct fib6_node' mostly allocated in
net/ipv6/route.c::__ip6_ins_rt() inside the lock_bh()/unlock_bh() section:

 write_lock_bh(&table->tb6_lock);
 err = fib6_add(&table->tb6_root, rt, info, mxc);
 write_unlock_bh(&table->tb6_lock);

In this case it is not enough to simply add SLAB_ACCOUNT to corresponding
kmem cache. The proper memory cgroup still cannot be found due to the
incorrect 'in_interrupt()' check used in memcg_kmem_bypass().

Obsoleted in_interrupt() does not describe real execution context properly.
From include/linux/preempt.h:

 The following macros are deprecated and should not be used in new code:
 in_interrupt()	- We're in NMI,IRQ,SoftIRQ context or have BH disabled

To verify the current execution context new macro should be used instead:
 in_task()	- We're in task context

Signed-off-by: Vasily Averin <redacted>
---
 mm/memcontrol.c      | 2 +-
 net/core/fib_rules.c | 4 ++--
 net/ipv4/devinet.c   | 2 +-
 net/ipv4/fib_trie.c  | 4 ++--
 net/ipv6/addrconf.c  | 2 +-
 net/ipv6/ip6_fib.c   | 4 ++--
 net/ipv6/route.c     | 2 +-
 7 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ae1f5d0..1bbf239 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c

@@ -968,7 +968,7 @@ static __always_inline bool memcg_kmem_bypass(void)
 		return false;
 
 	/* Memcg to charge can't be determined. */
-	if (in_interrupt() || !current->mm || (current->flags & PF_KTHREAD))
+	if (!in_task() || !current->mm || (current->flags & PF_KTHREAD))
 		return true;
 
 	return false;

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index a9f9379..79df7cd 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c

@@ -57,7 +57,7 @@ int fib_default_rule_add(struct fib_rules_ops *ops,
 {
 	struct fib_rule *r;
 
-	r = kzalloc(ops->rule_size, GFP_KERNEL);
+	r = kzalloc(ops->rule_size, GFP_KERNEL_ACCOUNT);
 	if (r == NULL)
 		return -ENOMEM;

@@ -541,7 +541,7 @@ static int fib_nl2rule(struct sk_buff *skb, struct nlmsghdr *nlh,
 			goto errout;
 	}
 
-	nlrule = kzalloc(ops->rule_size, GFP_KERNEL);
+	nlrule = kzalloc(ops->rule_size, GFP_KERNEL_ACCOUNT);
 	if (!nlrule) {
 		err = -ENOMEM;
 		goto errout;

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 73721a4..d38124b 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c

@@ -215,7 +215,7 @@ static void devinet_sysctl_unregister(struct in_device *idev)
 
 static struct in_ifaddr *inet_alloc_ifa(void)
 {
-	return kzalloc(sizeof(struct in_ifaddr), GFP_KERNEL);
+	return kzalloc(sizeof(struct in_ifaddr), GFP_KERNEL_ACCOUNT);
 }
 
 static void inet_rcu_free_ifa(struct rcu_head *head)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 25cf387..8060524 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c

@@ -2380,11 +2380,11 @@ void __init fib_trie_init(void)
 {
 	fn_alias_kmem = kmem_cache_create("ip_fib_alias",
 					  sizeof(struct fib_alias),
-					  0, SLAB_PANIC, NULL);
+					  0, SLAB_PANIC | SLAB_ACCOUNT, NULL);
 
 	trie_leaf_kmem = kmem_cache_create("ip_fib_trie",
 					   LEAF_SIZE,
-					   0, SLAB_PANIC, NULL);
+					   0, SLAB_PANIC | SLAB_ACCOUNT, NULL);
 }
 
 struct fib_table *fib_trie_table(u32 id, struct fib_table *alias)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 3bf685f..8eaeade 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c

@@ -1080,7 +1080,7 @@ static int ipv6_add_addr_hash(struct net_device *dev, struct inet6_ifaddr *ifa)
 			goto out;
 	}
 
-	ifa = kzalloc(sizeof(*ifa), gfp_flags);
+	ifa = kzalloc(sizeof(*ifa), gfp_flags | __GFP_ACCOUNT);
 	if (!ifa) {
 		err = -ENOBUFS;
 		goto out;

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 2d650dc..a8f118e 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c

@@ -2449,8 +2449,8 @@ int __init fib6_init(void)
 	int ret = -ENOMEM;
 
 	fib6_node_kmem = kmem_cache_create("fib6_nodes",
-					   sizeof(struct fib6_node),
-					   0, SLAB_HWCACHE_ALIGN,
+					   sizeof(struct fib6_node), 0,
+					   SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT,
 					   NULL);
 	if (!fib6_node_kmem)
 		goto out;

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 7b756a7..5f7286a 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c

@@ -6638,7 +6638,7 @@ int __init ip6_route_init(void)
 	ret = -ENOMEM;
 	ip6_dst_ops_template.kmem_cachep =
 		kmem_cache_create("ip6_dst_cache", sizeof(struct rt6_info), 0,
-				  SLAB_HWCACHE_ALIGN, NULL);
+				  SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT, NULL);
 	if (!ip6_dst_ops_template.kmem_cachep)
 		goto out;

-- 
1.8.3.1

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