From 425b9c7f51c98443db71ad679893725483b21196 Mon Sep 17 00:00:00 2001 From: Vasily Averin Date: Mon, 2 May 2022 15:15:51 +0300 Subject: memcg: accounting for objects allocated for new netdevice Creating a new netdevice allocates at least ~50Kb of memory for various kernel objects, but only ~5Kb of them are accounted to memcg. As a result, creating an unlimited number of netdevice inside a memcg-limited container does not fall within memcg restrictions, consumes a significant part of the host's memory, can cause global OOM and lead to random kills of host processes. The main consumers of non-accounted memory are: ~10Kb 80+ kernfs nodes ~6Kb ipv6_add_dev() allocations 6Kb __register_sysctl_table() allocations 4Kb neigh_sysctl_register() allocations 4Kb __devinet_sysctl_register() allocations 4Kb __addrconf_sysctl_register() allocations Accounting of these objects allows to increase the share of memcg-related memory up to 60-70% (~38Kb accounted vs ~54Kb total for dummy netdevice on typical VM with default Fedora 35 kernel) and this should be enough to somehow protect the host from misuse inside container. Other related objects are quite small and may not be taken into account to minimize the expected performance degradation. It should be separately mentonied ~300 bytes of percpu allocation of struct ipstats_mib in snmp6_alloc_dev(), on huge multi-cpu nodes it can become the main consumer of memory. This patch does not enables kernfs accounting as it affects other parts of the kernel and should be discussed separately. However, even without kernfs, this patch significantly improves the current situation and allows to take into account more than half of all netdevice allocations. Signed-off-by: Vasily Averin Acked-by: Luis Chamberlain Link: https://lore.kernel.org/r/354a0a5f-9ec3-a25c-3215-304eab2157bc@openvz.org Signed-off-by: Jakub Kicinski --- net/ipv4/devinet.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/ipv4/devinet.c') diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index 53a6b14dc50a..89141ba5e9ee 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -2573,7 +2573,7 @@ static int __devinet_sysctl_register(struct net *net, char *dev_name, struct devinet_sysctl_table *t; char path[sizeof("net/ipv4/conf/") + IFNAMSIZ]; - t = kmemdup(&devinet_sysctl, sizeof(*t), GFP_KERNEL); + t = kmemdup(&devinet_sysctl, sizeof(*t), GFP_KERNEL_ACCOUNT); if (!t) goto out; -- cgit v1.2.3