[PATCH v2 03/23] bpf: mark struct oom_control's memcg field as TRUSTED_OR_NULL

Roman Gushchin
2025-10-27T23:17:51Z

Struct oom_control is used to describe the OOM context.
It's memcg field defines the scope of OOM: it's NULL for global
OOMs and a valid memcg pointer for memcg-scoped OOMs.
Teach bpf verifier to recognize it as trusted or NULL pointer.
It will provide the bpf OOM handler a trusted memcg pointer,
which for example is required for iterating the memcg's subtree.

Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/verifier.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 542e23fb19c7..811275419be3 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7104,6 +7104,10 @@ BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct vm_area_struct) {
struct file *vm_file;
};

+BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct oom_control) {
+ struct mem_cgroup *memcg;
+};
+
static bool type_is_rcu(struct bpf_verifier_env *env,
struct bpf_reg_state *reg,
const char *field_name, u32 btf_id)
@@ -7146,6 +7150,7 @@ static bool type_is_trusted_or_null(struct bpf_verifier_env *env,
BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct vm_area_struct));
+ BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct oom_control));

return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id,
"__safe_trusted_or_null");
--
2.51.0