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| author | Eric Dumazet <edumazet@google.com> | 2023-03-07 08:22:54 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-17 10:50:27 +0300 |
| commit | 5b5b69e3185f482230a4481a619d05cf1c97ff7b (patch) | |
| tree | d9a66711d7c71d5dd363648a211357a9702139bf | |
| parent | b26b85b1846932e11de4693eddc5193aac14cfca (diff) | |
| download | linux-5b5b69e3185f482230a4481a619d05cf1c97ff7b.tar.xz | |
netfilter: conntrack: adopt safer max chain length
[ 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>
| -rw-r--r-- | net/netfilter/nf_conntrack_core.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 7f0f3bcaae03..30ed45b1b57d 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; |