From: Eric Dumazet edumazet@google.com
[ Upstream commit c77737b736ceb50fdf150434347dbd81ec76dbb1 ]
Customers using GKE 1.25 and 1.26 are facing conntrack issues root caused to commit c9c3b6811f74 ("netfilter: conntrack: make max chain length random").
Even if we assume Uniform Hashing, a bucket often reachs 8 chained items while the load factor of the hash table is smaller than 0.5
With a limit of 16, we reach load factors of 3. With a limit of 32, we reach load factors of 11. With a limit of 40, we reach load factors of 15. With a limit of 50, we reach load factors of 24.
This patch changes MIN_CHAINLEN to 50, to minimize risks.
Ideally, we could in the future add a cushion based on expected load factor (2 * nf_conntrack_max / nf_conntrack_buckets), because some setups might expect unusual values.
Fixes: c9c3b6811f74 ("netfilter: conntrack: make max chain length random") Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/nf_conntrack_core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 43ea8cfd374bb..7ff0da5f998a0 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -96,8 +96,8 @@ static DEFINE_MUTEX(nf_conntrack_mutex); #define GC_SCAN_MAX_DURATION msecs_to_jiffies(10) #define GC_SCAN_EXPIRED_MAX (64000u / HZ)
-#define MIN_CHAINLEN 8u -#define MAX_CHAINLEN (32u - MIN_CHAINLEN) +#define MIN_CHAINLEN 50u +#define MAX_CHAINLEN (80u - MIN_CHAINLEN)
static struct conntrack_gc_work conntrack_gc_work;