From: Fernando Fernandez Mancera After the optimization to only perform one GC per jiffy, a new problem was introduced. If more than 8 new connections are tracked per jiffy the list won't be cleaned up fast enough possibly reaching the limit wrongly. In order to prevent this issue, only skip the GC if it was already triggered during the same jiffy and the increment is lower than the clean up limit. In addition, increase the clean up limit to 64 connections to avoid triggering GC too often and do more effective GCs. This has been tested using a HTTP server and several performance tools while having nft_connlimit/xt_connlimit or OVS limit configured. Output of slowhttptest + OVS limit at 52000 connections: slow HTTP test status on 340th second: initializing: 0 pending: 432 connected: 51998 error: 0 closed: 0 service available: YES Fixes: d265929930e2 ("netfilter: nf_conncount: reduce unnecessary GC") Reported-by: Aleksandra Rukomoinikova Closes: https://lore.kernel.org/netfilter/b2064e7b-0776-4e14-adb6-c68080987471@k2.cloud/ Signed-off-by: Fernando Fernandez Mancera Signed-off-by: Florian Westphal --- include/net/netfilter/nf_conntrack_count.h | 1 + net/netfilter/nf_conncount.c | 15 ++++++++++----- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/include/net/netfilter/nf_conntrack_count.h b/include/net/netfilter/nf_conntrack_count.h index 52a06de41aa0..cf0166520cf3 100644 --- a/include/net/netfilter/nf_conntrack_count.h +++ b/include/net/netfilter/nf_conntrack_count.h @@ -13,6 +13,7 @@ struct nf_conncount_list { u32 last_gc; /* jiffies at most recent gc */ struct list_head head; /* connections with the same filtering key */ unsigned int count; /* length of list */ + unsigned int last_gc_count; /* length of list at most recent gc */ }; struct nf_conncount_data *nf_conncount_init(struct net *net, unsigned int keylen); diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c index 8487808c8761..288936f5c1bf 100644 --- a/net/netfilter/nf_conncount.c +++ b/net/netfilter/nf_conncount.c @@ -34,8 +34,9 @@ #define CONNCOUNT_SLOTS 256U -#define CONNCOUNT_GC_MAX_NODES 8 -#define MAX_KEYLEN 5 +#define CONNCOUNT_GC_MAX_NODES 8 +#define CONNCOUNT_GC_MAX_COLLECT 64 +#define MAX_KEYLEN 5 /* we will save the tuples of all connections we care about */ struct nf_conncount_tuple { @@ -182,12 +183,13 @@ static int __nf_conncount_add(struct net *net, goto out_put; } - if ((u32)jiffies == list->last_gc) + if ((u32)jiffies == list->last_gc && + (list->count - list->last_gc_count) < CONNCOUNT_GC_MAX_COLLECT) goto add_new_node; /* check the saved connections */ list_for_each_entry_safe(conn, conn_n, &list->head, node) { - if (collect > CONNCOUNT_GC_MAX_NODES) + if (collect > CONNCOUNT_GC_MAX_COLLECT) break; found = find_or_evict(net, list, conn); @@ -230,6 +232,7 @@ static int __nf_conncount_add(struct net *net, nf_ct_put(found_ct); } list->last_gc = (u32)jiffies; + list->last_gc_count = list->count; add_new_node: if (WARN_ON_ONCE(list->count > INT_MAX)) { @@ -277,6 +280,7 @@ void nf_conncount_list_init(struct nf_conncount_list *list) spin_lock_init(&list->list_lock); INIT_LIST_HEAD(&list->head); list->count = 0; + list->last_gc_count = 0; list->last_gc = (u32)jiffies; } EXPORT_SYMBOL_GPL(nf_conncount_list_init); @@ -316,13 +320,14 @@ static bool __nf_conncount_gc_list(struct net *net, } nf_ct_put(found_ct); - if (collected > CONNCOUNT_GC_MAX_NODES) + if (collected > CONNCOUNT_GC_MAX_COLLECT) break; } if (!list->count) ret = true; list->last_gc = (u32)jiffies; + list->last_gc_count = list->count; return ret; } -- 2.52.0