[v3] mm: BPF OOM

[PATCH bpf-next v3 05/17] bpf: mark struct oom_control's memcg field as TRUSTED_OR_NULL

Posted by Roman Gushchin 1 week, 4 days ago

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 c2f2650db9fd..cca36edb460d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7242,6 +7242,10 @@ 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)
@@ -7284,6 +7288,7 @@ 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");
-- 
2.52.0

Re: [PATCH bpf-next v3 05/17] bpf: mark struct oom_control's memcg field as TRUSTED_OR_NULL

Posted by Matt Bobrowski 5 days, 4 hours ago

On Mon, Jan 26, 2026 at 06:44:08PM -0800, Roman Gushchin wrote:
> 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.

This is fine. Feel free to add:

Acked-by: Matt Bobrowski <mattbobrowski@google.com>

> 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 c2f2650db9fd..cca36edb460d 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -7242,6 +7242,10 @@ 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)
> @@ -7284,6 +7288,7 @@ 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");
> -- 
> 2.52.0
>

Re: [PATCH bpf-next v3 05/17] bpf: mark struct oom_control's memcg field as TRUSTED_OR_NULL

Posted by Yafang Shao 1 week, 4 days ago

On Tue, Jan 27, 2026 at 10:49 AM Roman Gushchin
<roman.gushchin@linux.dev> wrote:
>
> 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>

Acked-by: Yafang Shao <laoar.shao@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 c2f2650db9fd..cca36edb460d 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -7242,6 +7242,10 @@ 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)
> @@ -7284,6 +7288,7 @@ 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");
> --
> 2.52.0
>
>


-- 
Regards
Yafang