6.15-stable review patch. If anyone has any objections, please let me know.
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From: Willem de Bruijn willemb@google.com
commit 5e9388f7984a9cc7e659a105113f6ccf0aebedd0 upstream.
The below commit that updated BPF_MAP_TYPE_LRU_HASH free target, also updated tools/testing/selftests/bpf/test_lru_map to match.
But that missed one case that passes with 4 cores, but fails at higher cpu counts.
Update test_lru_sanity3 to also adjust its expectation of target_free.
This time tested with 1, 4, 16, 64 and 384 cpu count.
Fixes: d4adf1c9ee77 ("bpf: Adjust free target to avoid global starvation of LRU map") Signed-off-by: Willem de Bruijn willemb@google.com Link: https://lore.kernel.org/r/20250625210412.2732970-1-willemdebruijn.kernel@gma... Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/testing/selftests/bpf/test_lru_map.c | 33 +++++++++++++++-------------- 1 file changed, 18 insertions(+), 15 deletions(-)
--- a/tools/testing/selftests/bpf/test_lru_map.c +++ b/tools/testing/selftests/bpf/test_lru_map.c @@ -138,6 +138,12 @@ static int sched_next_online(int pid, in return ret; }
+/* Derive target_free from map_size, same as bpf_common_lru_populate */ +static unsigned int __tgt_size(unsigned int map_size) +{ + return (map_size / nr_cpus) / 2; +} + /* Inverse of how bpf_common_lru_populate derives target_free from map_size. */ static unsigned int __map_size(unsigned int tgt_free) { @@ -410,12 +416,12 @@ static void test_lru_sanity2(int map_typ printf("Pass\n"); }
-/* Size of the LRU map is 2*tgt_free - * It is to test the active/inactive list rotation - * Insert 1 to 2*tgt_free (+2*tgt_free keys) - * Lookup key 1 to tgt_free*3/2 - * Add 1+2*tgt_free to tgt_free*5/2 (+tgt_free/2 keys) - * => key 1+tgt_free*3/2 to 2*tgt_free are removed from LRU +/* Test the active/inactive list rotation + * + * Fill the whole map, deplete the free list. + * Reference all except the last lru->target_free elements. + * Insert lru->target_free new elements. This triggers one shrink. + * Verify that the non-referenced elements are replaced. */ static void test_lru_sanity3(int map_type, int map_flags, unsigned int tgt_free) { @@ -434,8 +440,7 @@ static void test_lru_sanity3(int map_typ
assert(sched_next_online(0, &next_cpu) != -1);
- batch_size = tgt_free / 2; - assert(batch_size * 2 == tgt_free); + batch_size = __tgt_size(tgt_free);
map_size = tgt_free * 2; lru_map_fd = create_map(map_type, map_flags, map_size); @@ -446,23 +451,21 @@ static void test_lru_sanity3(int map_typ
value[0] = 1234;
- /* Insert 1 to 2*tgt_free (+2*tgt_free keys) */ - end_key = 1 + (2 * tgt_free); + /* Fill the map */ + end_key = 1 + map_size; for (key = 1; key < end_key; key++) assert(!bpf_map_update_elem(lru_map_fd, &key, value, BPF_NOEXIST));
- /* Lookup key 1 to tgt_free*3/2 */ - end_key = tgt_free + batch_size; + /* Reference all but the last batch_size */ + end_key = 1 + map_size - batch_size; for (key = 1; key < end_key; key++) { assert(!bpf_map_lookup_elem_with_ref_bit(lru_map_fd, key, value)); assert(!bpf_map_update_elem(expected_map_fd, &key, value, BPF_NOEXIST)); }
- /* Add 1+2*tgt_free to tgt_free*5/2 - * (+tgt_free/2 keys) - */ + /* Insert new batch_size: replaces the non-referenced elements */ key = 2 * tgt_free + 1; end_key = key + batch_size; for (; key < end_key; key++) {