Re: [PATCH v3 1/2] bpf: Tighten cgroup storage cookie checks for prog arrays

[bot+bpf-ci]

> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index a656a8572bdb..d85869544dc8 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -2480,8 +2480,12 @@ static bool __bpf_prog_map_compatible(struct bpf_map *map,
>  				break;
>  			cookie = aux->cgroup_storage[i] ?
>  				 aux->cgroup_storage[i]->cookie : 0;
> -			ret = map->owner->storage_cookie[i] == cookie ||
> -			      !cookie;
> +			/*
> +			 * Tail calls keep using the caller cgroup storage
> +			 * context, so prog-array members must use the same
> +			 * storage cookie.
> +			 */
> +			ret = map->owner->storage_cookie[i] == cookie;
>  		}
>  		if (ret &&
>  		    map->owner->attach_func_proto != aux->attach_func_proto) {

Related to this patch series, Leon Hwang raised a concern about test
placement in the selftest file (tools/testing/selftests/bpf/prog_tests/
tailcalls.c). The new cgroup storage tail-call tests should be placed at
the tail of test_tailcalls() rather than before tailcall_failure and
tailcall_sleepable.

Reference: https://lore.kernel.org/bpf/20260603150213.68746-1-leon.hwang@xxxxxxxxx/

Leon's comment from v2: "These new ones should stay at the tail of
test_tailcalls()."

Should the test ordering be adjusted in the selftest file to address this
feedback?


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