selftests: cgroup: fix unexpected failure on test_memcg_sock

Before server got a client connection, there were some memory allocations
in the test memcg, such as user stack.  So do not count those allocations
which are not related to socket when checking socket memory accounting.

Link: https://lkml.kernel.org/r/20230619124735.2124-1-haifeng.xu@shopee.com
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index a2a90f4bfe9fe5788f5e03850d88f4e991cb14d6..c7c9572003a8c9efa29a179e4121a243112c63be 100644 (file)
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -989,7 +989,9 @@ static int tcp_client(const char *cgroup, unsigned short port)
        char servport[6];
        int retries = 0x10; /* nice round number */
        int sk, ret;
+       long allocated;
 
+       allocated = cg_read_long(cgroup, "memory.current");
        snprintf(servport, sizeof(servport), "%hd", port);
        ret = getaddrinfo(server, servport, NULL, &ai);
        if (ret)
@@ -1017,7 +1019,8 @@ static int tcp_client(const char *cgroup, unsigned short port)
                if (current < 0 || sock < 0)
                        goto close_sk;
 
-               if (values_close(current, sock, 10)) {
+               /* exclude the memory not related to socket connection */
+               if (values_close(current - allocated, sock, 10)) {
                        ret = KSFT_PASS;
                        break;
                }