Re: [PATCH bpf-next v3 2/2] bpf: Add deep call stack selftests

[Eduard Zingerman <eddyz87@gmail.com>]

On Mon, 2026-03-02 at 23:31 -0500, Emil Tsalapatis wrote:
> Add tests that demonstrate the verifier support for deep call stacks
> while still enforcing maximum stack size limits.
> 
> Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

[...]

> +/* Check we actually honor stack limits (33 * 16 = 528 > 512 = MAX_STACK_DEPTH). */

Nit: I was wondering why stack usage per func is 16, as each one only
     consumes one slot. Turns out round_up_stack_depth() rounds things
     up to 16. Could you please either add a comment here, or just add
     a second long in each function?

> +SEC("syscall")
> +__failure __msg("combined stack size of 34 calls")
> +int global_func_deep_stack_fail(struct __sk_buff *skb)
> +{
> +	return f32(123);
> +}