[LTP] [PATCH v3] memcg/memcontrol04: Fix judgment for recursive_protection

[Jin Guojie]

V3:
* Fix initialization of root->memory_recursiveprot
* The use of tst_cg_memory_recursiveprot(leaf_cg[F]) is changed to safe check
* The type of memory_recursiveprot is changed to unsigned int
* Rebase the code to the latest branch

V2:
* Change the expected events in F depending on memory_recursiveprot

On distributions with memory_recursiveprot enabled by default (from
Ubuntu 22.04 to 24.10), running this passes：

memcontrol04.c:208: TPASS: Expect: (C oom events=0) == 0
memcontrol04.c:214: TPASS: Expect: (C low events=964) > 0
memcontrol04.c:208: TPASS: Expect: (D oom events=0) == 0
memcontrol04.c:214: TPASS: Expect: (D low events=964) > 0
memcontrol04.c:208: TPASS: Expect: (E oom events=0) == 0
memcontrol04.c:211: TPASS: Expect: (E low events=0) == 0
memcontrol04.c:208: TPASS: Expect: (F oom events=0) == 0
memcontrol04.c:214: TPASS: Expect: (F low events=878) > 0

[1] https://lists.linux.it/pipermail/ltp/2024-November/040946.html
[2] https://lists.linux.it/pipermail/ltp/2024-December/041316.html

Signed-off-by: Jin Guojie <guojie.jin@gmail.com>
Suggested-by: Richard Palethorpe <rpalethorpe@suse.com>
Suggested-by: Michal Koutný <mkoutny@suse.com>
Suggested-by: Wei Gao <wegao@suse.com>
Suggested-by: Li Wang <liwang@redhat.com>
---
 include/tst_cgroup.h                              |  2 ++
 lib/tst_cgroup.c                                  | 13 +++++++++++++
 testcases/kernel/controllers/memcg/memcontrol04.c |  8 ++++----
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/include/tst_cgroup.h b/include/tst_cgroup.h
index d23a8e652..068ff8306 100644
--- a/include/tst_cgroup.h
+++ b/include/tst_cgroup.h
@@ -256,4 +256,6 @@ int safe_cg_occursin(const char *file, const int lineno,
                         const char *const file_name,
                         const char *const needle);

+int tst_cg_memory_recursiveprot(struct tst_cg_group *cg);
+
 #endif /* TST_CGROUP_H */
diff --git a/lib/tst_cgroup.c b/lib/tst_cgroup.c
index 6055015eb..1f9354ba4 100644
--- a/lib/tst_cgroup.c
+++ b/lib/tst_cgroup.c
@@ -76,6 +76,8 @@ struct cgroup_root {
        int we_mounted_it:1;
        /* cpuset is in compatability mode */
        int no_cpuset_prefix:1;
+
+       unsigned int memory_recursiveprot:1;
 };

 /* Controller sub-systems */
@@ -576,6 +578,7 @@ static void cgroup_root_scan(const char *const mnt_type,
        uint32_t ctrl_field = 0;
        int no_prefix = 0;
        int nsdelegate = 0;
+       int memory_recursiveprot = 0;
        char buf[BUFSIZ];
        char *tok;
        const int mnt_dfd = SAFE_OPEN(mnt_dir, O_PATH | O_DIRECTORY);
@@ -592,6 +595,7 @@ static void cgroup_root_scan(const char *const mnt_type,
        }
        for (tok = strtok(mnt_opts, ","); tok; tok = strtok(NULL, ",")) {
                nsdelegate |= !strcmp("nsdelegate", tok);
+               memory_recursiveprot |= !strcmp("memory_recursiveprot", tok);
        }

        if (root->ver && ctrl_field == root->ctrl_field)
@@ -644,6 +648,7 @@ backref:
        root->ctrl_field = ctrl_field;
        root->no_cpuset_prefix = no_prefix;
        root->nsdelegate = nsdelegate;
+       root->memory_recursiveprot = memory_recursiveprot;

        for_each_ctrl(ctrl) {
                if (has_ctrl(root->ctrl_field, ctrl))
@@ -1509,3 +1514,11 @@ int safe_cg_occursin(const char *const file,
const int lineno,

        return !!strstr(buf, needle);
 }
+
+int tst_cg_memory_recursiveprot(struct tst_cg_group *cg)
+{
+       if (cg && cg->dirs_by_ctrl[0]->dir_root)
+               return cg->dirs_by_ctrl[0]->dir_root->memory_recursiveprot;
+       return 0;
+}
+
diff --git a/testcases/kernel/controllers/memcg/memcontrol04.c
b/testcases/kernel/controllers/memcg/memcontrol04.c
index 1b8d115f8..0a77f6681 100644
--- a/testcases/kernel/controllers/memcg/memcontrol04.c
+++ b/testcases/kernel/controllers/memcg/memcontrol04.c
@@ -207,12 +207,12 @@ static void test_memcg_low(void)

                TST_EXP_EXPR(oom == 0, "(%c oom events=%ld) == 0", id, oom);

-               if (i < E) {
-                       TST_EXP_EXPR(low > 0,
-                                    "(%c low events=%ld) > 0", id, low);
-               } else {
+               if (i == E || ((i == F) &&
!tst_cg_memory_recursiveprot(leaf_cg[F]))) {
                        TST_EXP_EXPR(low == 0,
                                     "(%c low events=%ld) == 0", id, low);
+               } else {
+                       TST_EXP_EXPR(low > 0,
+                                    "(%c low events=%ld) > 0", id, low);
                }
        }

--
2.34.1