Generate a random interval set, then flush and reload it a few times.
Note that this test fails with several up-to-date distros that lack
nft commit e83e32c8d1cd ("mnl: restore create element command with large batches").

This hints that we will likely need to revert
648946966a08 ("netfilter: nft_set_rbtree: validate open interval overlap") soon,
or risk major breakage in most current distros .

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 .../transactions/dumps/large_rbtree.nodump    |   0
 .../testcases/transactions/large_rbtree.sh    | 123 ++++++++++++++++++
 2 files changed, 123 insertions(+)
 create mode 100644 tests/shell/testcases/transactions/dumps/large_rbtree.nodump
 create mode 100755 tests/shell/testcases/transactions/large_rbtree.sh

diff --git a/tests/shell/testcases/transactions/dumps/large_rbtree.nodump b/tests/shell/testcases/transactions/dumps/large_rbtree.nodump
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/tests/shell/testcases/transactions/large_rbtree.sh b/tests/shell/testcases/transactions/large_rbtree.sh
new file mode 100755
index 000000000000..09b16c5d70e9
--- /dev/null
+++ b/tests/shell/testcases/transactions/large_rbtree.sh
@@ -0,0 +1,123 @@
+#!/bin/bash
+
+# load+reload a large, randomly generated rbtree set
+
+set -e
+
+MAXSIZE=50000
+tmpfile=$(mktemp)
+
+cleanup()
+{
+	# error? Dump the failed set
+	test -r "$tmpfile" && cat "$tmpfile"
+	rm -f "$tmpfile"
+}
+trap cleanup EXIT
+
+create_elements() {
+	local howmany=$1
+	local a=10
+	local b=0
+	local c=0
+	local d=1
+	local e=0
+	local i=0
+
+	while [ $i -le $howmany ];do
+		local step1=$((RANDOM%50))
+		d=$((d+step1))
+		if [ $d -ge 256 ];then
+			d=1
+			c=$((c+1))
+		fi
+
+		if [ $c -ge 256 ];then
+			b=$((b+1))
+			c=0
+		fi
+
+		if [ $b -ge 256 ];then
+			a=$((a+1))
+			b=0
+		fi
+
+		echo -n "$a.$b.$c.$d-"
+
+		local step2=$((RANDOM%10))
+		e=$((d+step2))
+		d=$((e+1))
+		if [ $e -ge 256 ];then
+			e=0
+			c=$((c+1))
+		fi
+
+		if [ $c -ge 256 ];then
+			b=$((b+1))
+			c=0
+		fi
+
+		if [ $b -ge 256 ];then
+			a=$((a+1))
+			b=0
+		fi
+
+		echo -n "$a.$b.$c.$e"
+		[ $i -lt $howmany ] && echo ", "
+		i=$((i+1))
+	done
+
+	echo "}"
+}
+
+create_set() {
+cat - <<EOF
+table ip t {
+	set s {
+		typeof ip saddr
+		flags interval
+		elements = {
+EOF
+
+local size1=$((RANDOM+1))
+local size2=$((RANDOM+1))
+
+create_elements $(((size1 * size2) % MAXSIZE))
+
+echo "}"
+}
+
+create_ruleset() {
+	create_set
+cat - <<EOF
+	chain input {
+		type filter hook input priority 0
+
+		ip saddr @s counter
+	}
+}
+EOF
+}
+
+recreate_set() {
+	create_set
+
+	# closes table
+	echo "}"
+}
+
+create_ruleset > "$tmpfile"
+
+# load set
+$NFT -f "$tmpfile"
+
+# flush + reload the same, then different sets
+reloads=$(((RANDOM%5)+1))
+for i in $(seq 1 $reloads); do
+	echo reload:
+	wc -l $tmpfile
+	( echo flush set t s ; cat "$tmpfile" ) | $NFT -f -
+	recreate_set > "$tmpfile"
+done
+
+rm -f "$tmpfile"
-- 
2.52.0