linux-kernel - [RFC PATCH bpf-next v3 03/12] bpf: mark struct oom_control's memcg field as TRUSTED_OR

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Message-ID: <27af33f679846a2783cc8d82111ebeac170b004c.1769157382.git.zhuhui@kylinos.cn>
Date: Fri, 23 Jan 2026 16:55:21 +0800
From: Hui Zhu <hui.zhu@...ux.dev>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...nel.org>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
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Cc: Kumar Kartikeya Dwivedi <memxor@...il.com>
Subject: [RFC PATCH bpf-next v3 03/12] bpf: mark struct oom_control's memcg field as TRUSTED_OR_NULL

From: Roman Gushchin <roman.gushchin@...ux.dev>

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@...ux.dev>
Acked-by: Kumar Kartikeya Dwivedi <memxor@...il.com>
---
 kernel/bpf/verifier.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 7a375f608263..e59acdbb5062 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7152,6 +7152,10 @@ 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)
@@ -7194,6 +7198,7 @@ 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");
-- 
2.43.0