Re: [PATCH bpf v4 3/3] bpf: Cache build IDs in sleepable stackmap path

[Alexei Starovoitov]

On Thu, May 14, 2026 at 11:48 AM Ihor Solodrai <ihor.solodrai@xxxxxxxxx> wrote:
>
> Stack traces often contain adjacent IPs from the same VMA or from
> different VMAs backed by the same ELF file. Cache the last successfully
> parsed build ID together with the resolved VMA range and backing file
> so the sleepable build-ID path can avoid repeated VMA locking and file
> parsing in common cases.
>
> Suggested-by: Mykyta Yatsenko <yatsenko@xxxxxxxx>
> Acked-by: Mykyta Yatsenko <yatsenko@xxxxxxxx>
> Signed-off-by: Ihor Solodrai <ihor.solodrai@xxxxxxxxx>
> ---
>  kernel/bpf/stackmap.c | 56 ++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 53 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
> index c1e96df360c3..8a18c9645933 100644
> --- a/kernel/bpf/stackmap.c
> +++ b/kernel/bpf/stackmap.c
> @@ -226,13 +226,33 @@ static void stack_map_get_build_id_offset_sleepable(struct bpf_stack_build_id *i
>                 .vma = NULL,
>                 .mm = mm,
>         };
> -       unsigned long vm_pgoff, vm_start;
> +       struct {
> +               struct file *file;
> +               const unsigned char *build_id;
> +               unsigned long vm_start;
> +               unsigned long vm_end;
> +               unsigned long vm_pgoff;
> +       } cache = {};
> +       unsigned long vm_pgoff, vm_start, vm_end;

cache logic cannot go into bpf. it's not a fix.
So either drop it or the whole thing into bpf-next.
Which is probably better.