The test does the following for IPv4/IPv6 x TCP/UDP sockets
with/without SK_BPF_MEMCG_SOCK_ISOLATED.
1. Create socket pairs
2. Send a bunch of data that requires more than 1024 pages
3. Read memory_allocated from sk->sk_prot->memory_allocated and
sk->sk_prot->memory_per_cpu_fw_alloc
4. Check if unread data is charged to memory_allocated
If SK_BPF_MEMCG_SOCK_ISOLATED is set, memory_allocated should not
be changed, but we allow a small error (up to 10 pages) in case
other processes on the host use some amounts of TCP/UDP memory.
The amount of allocated pages are buffered to per-cpu variable
{tcp,udp}_memory_per_cpu_fw_alloc up to +/- net.core.mem_pcpu_rsv
before reported to {tcp,udp}_memory_allocated.
At 3., memory_allocated is calculated from the 2 variables twice
at fentry and fexit of socket create function to check if the per-cpu
value is drained during calculation. In that case, 3. is retried.
We use kern_sync_rcu() for UDP because UDP recv queue is destroyed
after RCU grace period.
The test takes ~2s on QEMU (64 CPUs) w/ KVM but takes 6s w/o KVM.
# time ./test_progs -t sk_memcg
#370/1 sk_memcg/TCP :OK
#370/2 sk_memcg/UDP :OK
#370/3 sk_memcg/TCPv6:OK
#370/4 sk_memcg/UDPv6:OK
#370 sk_memcg:OK
Summary: 1/4 PASSED, 0 SKIPPED, 0 FAILED
real 0m1.623s
user 0m0.165s
sys 0m0.366s
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
---
v6:
* Trace sk_prot->memory_allocated + sk_prot->memory_per_cpu_fw_alloc
v5:
* Use kern_sync_rcu()
* Double NR_SEND to 128
v4:
* Only use inet_create() hook
* Test bpf_getsockopt()
* Add serial_ prefix
* Reduce sleep() and the amount of sent data
---
.../selftests/bpf/prog_tests/sk_memcg.c | 236 ++++++++++++++++++
tools/testing/selftests/bpf/progs/sk_memcg.c | 146 +++++++++++
2 files changed, 382 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/sk_memcg.c
create mode 100644 tools/testing/selftests/bpf/progs/sk_memcg.c
diff --git a/tools/testing/selftests/bpf/prog_tests/sk_memcg.c b/tools/testing/selftests/bpf/prog_tests/sk_memcg.c
new file mode 100644
index 000000000000..c6152240a6b7
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/sk_memcg.c
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2025 Google LLC */
+
+#include <test_progs.h>
+#include "sk_memcg.skel.h"
+#include "network_helpers.h"
+
+#define NR_SOCKETS 64
+#define NR_SEND 128
+#define BUF_SINGLE 1024
+#define BUF_TOTAL (BUF_SINGLE * NR_SEND)
+
+struct test_case {
+ char name[8];
+ int family;
+ int type;
+ int (*create_sockets)(struct test_case *test_case, int sk[], int len);
+ long (*get_memory_allocated)(struct test_case *test_case, struct sk_memcg *skel);
+};
+
+static int tcp_create_sockets(struct test_case *test_case, int sk[], int len)
+{
+ int server, i;
+
+ server = start_server(test_case->family, test_case->type, NULL, 0, 0);
+ ASSERT_GE(server, 0, "start_server_str");
+
+ for (i = 0; i < len / 2; i++) {
+ sk[i * 2] = connect_to_fd(server, 0);
+ if (!ASSERT_GE(sk[i * 2], 0, "connect_to_fd"))
+ return sk[i * 2];
+
+ sk[i * 2 + 1] = accept(server, NULL, NULL);
+ if (!ASSERT_GE(sk[i * 2 + 1], 0, "accept"))
+ return sk[i * 2 + 1];
+ }
+
+ close(server);
+
+ return 0;
+}
+
+static int udp_create_sockets(struct test_case *test_case, int sk[], int len)
+{
+ int i, err, rcvbuf = BUF_TOTAL;
+
+ for (i = 0; i < len / 2; i++) {
+ sk[i * 2] = start_server(test_case->family, test_case->type, NULL, 0, 0);
+ if (!ASSERT_GE(sk[i * 2], 0, "start_server"))
+ return sk[i * 2];
+
+ sk[i * 2 + 1] = connect_to_fd(sk[i * 2], 0);
+ if (!ASSERT_GE(sk[i * 2 + 1], 0, "connect_to_fd"))
+ return sk[i * 2 + 1];
+
+ err = connect_fd_to_fd(sk[i * 2], sk[i * 2 + 1], 0);
+ if (!ASSERT_EQ(err, 0, "connect_fd_to_fd"))
+ return err;
+
+ err = setsockopt(sk[i * 2], SOL_SOCKET, SO_RCVBUF, &rcvbuf, sizeof(int));
+ if (!ASSERT_EQ(err, 0, "setsockopt(SO_RCVBUF)"))
+ return err;
+
+ err = setsockopt(sk[i * 2 + 1], SOL_SOCKET, SO_RCVBUF, &rcvbuf, sizeof(int));
+ if (!ASSERT_EQ(err, 0, "setsockopt(SO_RCVBUF)"))
+ return err;
+ }
+
+ return 0;
+}
+
+static long get_memory_allocated(struct test_case *test_case,
+ bool *activated, bool *stable,
+ long *memory_allocated)
+{
+ *stable = false;
+
+ do {
+ *activated = true;
+
+ /* AF_INET and AF_INET6 share the same memory_allocated.
+ * tcp_init_sock() is called by AF_INET and AF_INET6,
+ * but udp_lib_init_sock() is inline.
+ */
+ socket(AF_INET, test_case->type, 0);
+ } while (!*stable);
+
+ return *memory_allocated;
+}
+
+static long tcp_get_memory_allocated(struct test_case *test_case, struct sk_memcg *skel)
+{
+ return get_memory_allocated(test_case,
+ &skel->bss->tcp_activated,
+ &skel->bss->tcp_stable,
+ &skel->bss->tcp_memory_allocated);
+}
+
+static long udp_get_memory_allocated(struct test_case *test_case, struct sk_memcg *skel)
+{
+ return get_memory_allocated(test_case,
+ &skel->bss->udp_activated,
+ &skel->bss->udp_stable,
+ &skel->bss->udp_memory_allocated);
+}
+
+static int check_isolated(struct test_case *test_case,
+ struct sk_memcg *skel, bool isolated)
+{
+ char buf[BUF_SINGLE] = {};
+ long memory_allocated[2];
+ int sk[NR_SOCKETS] = {};
+ int err, i, j;
+
+ err = test_case->create_sockets(test_case, sk, ARRAY_SIZE(sk));
+ if (err)
+ goto close;
+
+ memory_allocated[0] = test_case->get_memory_allocated(test_case, skel);
+
+ /* allocate pages >= 1024 */
+ for (i = 0; i < ARRAY_SIZE(sk); i++) {
+ for (j = 0; j < NR_SEND; j++) {
+ int bytes = send(sk[i], buf, sizeof(buf), 0);
+
+ /* Avoid too noisy logs when something failed. */
+ if (bytes != sizeof(buf)) {
+ ASSERT_EQ(bytes, sizeof(buf), "send");
+ if (bytes < 0) {
+ err = bytes;
+ goto close;
+ }
+ }
+ }
+ }
+
+ memory_allocated[1] = test_case->get_memory_allocated(test_case, skel);
+
+ if (isolated)
+ ASSERT_LE(memory_allocated[1], memory_allocated[0] + 10, "isolated");
+ else
+ ASSERT_GT(memory_allocated[1], memory_allocated[0] + 1024, "not isolated");
+
+close:
+ for (i = 0; i < ARRAY_SIZE(sk); i++)
+ close(sk[i]);
+
+ if (test_case->type == SOCK_DGRAM) {
+ /* UDP recv queue is destroyed after RCU grace period.
+ * With one kern_sync_rcu(), memory_allocated[0] of the
+ * isoalted case often matches with memory_allocated[1]
+ * of the preceding non-isolated case.
+ */
+ kern_sync_rcu();
+ kern_sync_rcu();
+ }
+
+ return err;
+}
+
+void run_test(struct test_case *test_case)
+{
+ struct sk_memcg *skel;
+ int cgroup, err;
+
+ skel = sk_memcg__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "open_and_load"))
+ return;
+
+ skel->bss->nr_cpus = libbpf_num_possible_cpus();
+
+ err = sk_memcg__attach(skel);
+ if (!ASSERT_OK(err, "attach"))
+ goto destroy_skel;
+
+ cgroup = test__join_cgroup("/sk_memcg");
+ if (!ASSERT_GE(cgroup, 0, "join_cgroup"))
+ goto destroy_skel;
+
+ err = check_isolated(test_case, skel, false);
+ if (!ASSERT_EQ(err, 0, "test_isolated(false)"))
+ goto close_cgroup;
+
+ skel->links.sock_create = bpf_program__attach_cgroup(skel->progs.sock_create, cgroup);
+ if (!ASSERT_OK_PTR(skel->links.sock_create, "attach_cgroup(sock_create)"))
+ goto close_cgroup;
+
+ err = check_isolated(test_case, skel, true);
+ ASSERT_EQ(err, 0, "test_isolated(false)");
+
+close_cgroup:
+ close(cgroup);
+destroy_skel:
+ sk_memcg__destroy(skel);
+}
+
+struct test_case test_cases[] = {
+ {
+ .name = "TCP ",
+ .family = AF_INET,
+ .type = SOCK_STREAM,
+ .create_sockets = tcp_create_sockets,
+ .get_memory_allocated = tcp_get_memory_allocated,
+ },
+ {
+ .name = "UDP ",
+ .family = AF_INET,
+ .type = SOCK_DGRAM,
+ .create_sockets = udp_create_sockets,
+ .get_memory_allocated = udp_get_memory_allocated,
+ },
+ {
+ .name = "TCPv6",
+ .family = AF_INET6,
+ .type = SOCK_STREAM,
+ .create_sockets = tcp_create_sockets,
+ .get_memory_allocated = tcp_get_memory_allocated,
+ },
+ {
+ .name = "UDPv6",
+ .family = AF_INET6,
+ .type = SOCK_DGRAM,
+ .create_sockets = udp_create_sockets,
+ .get_memory_allocated = udp_get_memory_allocated,
+ },
+};
+
+void serial_test_sk_memcg(void)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
+ test__start_subtest(test_cases[i].name);
+ run_test(&test_cases[i]);
+ }
+}
diff --git a/tools/testing/selftests/bpf/progs/sk_memcg.c b/tools/testing/selftests/bpf/progs/sk_memcg.c
new file mode 100644
index 000000000000..cd46d6dfa73c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/sk_memcg.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright 2025 Google LLC */
+
+#include "bpf_tracing_net.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <errno.h>
+
+extern int tcp_memory_per_cpu_fw_alloc __ksym;
+extern int udp_memory_per_cpu_fw_alloc __ksym;
+
+int nr_cpus;
+bool tcp_activated, tcp_stable, udp_activated, udp_stable;
+long tcp_memory_allocated, udp_memory_allocated;
+static struct sock *tcp_sk_tracing, *udp_sk_tracing;
+
+struct sk_prot {
+ long *memory_allocated;
+ int *memory_per_cpu_fw_alloc;
+};
+
+static int drain_memory_per_cpu_fw_alloc(__u32 i, struct sk_prot *sk_prot_ctx)
+{
+ int *memory_per_cpu_fw_alloc;
+
+ memory_per_cpu_fw_alloc = bpf_per_cpu_ptr(sk_prot_ctx->memory_per_cpu_fw_alloc, i);
+ if (memory_per_cpu_fw_alloc)
+ *sk_prot_ctx->memory_allocated += *memory_per_cpu_fw_alloc;
+
+ return 0;
+}
+
+static long get_memory_allocated(struct sock *_sk, int *memory_per_cpu_fw_alloc)
+{
+ struct sock *sk = bpf_core_cast(_sk, struct sock);
+ struct sk_prot sk_prot_ctx;
+ long memory_allocated;
+
+ /* net_aligned_data.{tcp,udp}_memory_allocated was not available. */
+ memory_allocated = sk->__sk_common.skc_prot->memory_allocated->counter;
+
+ sk_prot_ctx.memory_allocated = &memory_allocated;
+ sk_prot_ctx.memory_per_cpu_fw_alloc = memory_per_cpu_fw_alloc;
+
+ bpf_loop(nr_cpus, drain_memory_per_cpu_fw_alloc, &sk_prot_ctx, 0);
+
+ return memory_allocated;
+}
+
+static void fentry_init_sock(struct sock *sk, struct sock **sk_tracing,
+ long *memory_allocated, int *memory_per_cpu_fw_alloc,
+ bool *activated)
+{
+ if (!*activated)
+ return;
+
+ if (__sync_val_compare_and_swap(sk_tracing, NULL, sk))
+ return;
+
+ *activated = false;
+ *memory_allocated = get_memory_allocated(sk, memory_per_cpu_fw_alloc);
+}
+
+static void fexit_init_sock(struct sock *sk, struct sock **sk_tracing,
+ long *memory_allocated, int *memory_per_cpu_fw_alloc,
+ bool *stable)
+{
+ long new_memory_allocated;
+
+ if (sk != *sk_tracing)
+ return;
+
+ new_memory_allocated = get_memory_allocated(sk, memory_per_cpu_fw_alloc);
+ if (new_memory_allocated == *memory_allocated)
+ *stable = true;
+
+ *sk_tracing = NULL;
+}
+
+SEC("fentry/tcp_init_sock")
+int BPF_PROG(fentry_tcp_init_sock, struct sock *sk)
+{
+ fentry_init_sock(sk, &tcp_sk_tracing,
+ &tcp_memory_allocated, &tcp_memory_per_cpu_fw_alloc,
+ &tcp_activated);
+ return 0;
+}
+
+SEC("fexit/tcp_init_sock")
+int BPF_PROG(fexit_tcp_init_sock, struct sock *sk)
+{
+ fexit_init_sock(sk, &tcp_sk_tracing,
+ &tcp_memory_allocated, &tcp_memory_per_cpu_fw_alloc,
+ &tcp_stable);
+ return 0;
+}
+
+SEC("fentry/udp_init_sock")
+int BPF_PROG(fentry_udp_init_sock, struct sock *sk)
+{
+ fentry_init_sock(sk, &udp_sk_tracing,
+ &udp_memory_allocated, &udp_memory_per_cpu_fw_alloc,
+ &udp_activated);
+ return 0;
+}
+
+SEC("fexit/udp_init_sock")
+int BPF_PROG(fexit_udp_init_sock, struct sock *sk)
+{
+ fexit_init_sock(sk, &udp_sk_tracing,
+ &udp_memory_allocated, &udp_memory_per_cpu_fw_alloc,
+ &udp_stable);
+ return 0;
+}
+
+SEC("cgroup/sock_create")
+int sock_create(struct bpf_sock *ctx)
+{
+ u32 flags = SK_BPF_MEMCG_SOCK_ISOLATED;
+ int err;
+
+ err = bpf_setsockopt(ctx, SOL_SOCKET, SK_BPF_MEMCG_FLAGS,
+ &flags, sizeof(flags));
+ if (err)
+ goto err;
+
+ flags = 0;
+
+ err = bpf_getsockopt(ctx, SOL_SOCKET, SK_BPF_MEMCG_FLAGS,
+ &flags, sizeof(flags));
+ if (err)
+ goto err;
+
+ if (flags != SK_BPF_MEMCG_SOCK_ISOLATED) {
+ err = -EINVAL;
+ goto err;
+ }
+
+ return 1;
+
+err:
+ bpf_set_retval(err);
+ return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
--
2.51.0.384.g4c02a37b29-goog
