Re: next/master bisection: baseline.login on qemu_arm64-virt-gicv3-uefi

[Puranjay Mohan <puranjay12@gmail.com>]

Hi Song,

>
> bpf_prog_pack gives benefits without using PMD pages. For arm64
> with 64kB page, even bpf_prog_pack of 64kB can fit multiple bpf
> programs in it. OTOH, 512MB is really big.
>
> How about we do something like the following?
>
> Thanks,
> Song
>
> diff --git i/kernel/bpf/core.c w/kernel/bpf/core.c
> index 9ee4536d0a09..1fe05c280e31 100644
> --- i/kernel/bpf/core.c
> +++ w/kernel/bpf/core.c
> @@ -888,7 +888,15 @@ static LIST_HEAD(pack_list);
>   * CONFIG_MMU=n. Use PAGE_SIZE in these cases.
>   */
>  #ifdef PMD_SIZE
> -#define BPF_PROG_PACK_SIZE (PMD_SIZE * num_possible_nodes())
> +  /* PMD_SIZE is really big for some archs. It doesn't make sense to
> +   * reserve too much memory in one allocation. Cap BPF_PROG_PACK_SIZE to
> +   * 2MiB * num_possible_nodes().
> +   */
> +  #if PMD_SIZE <= (1 << 21)
> +    #define BPF_PROG_PACK_SIZE (PMD_SIZE * num_possible_nodes())
> +  #else
> +    #define BPF_PROG_PACK_SIZE ((1 << 21) * num_possible_nodes())
> +  #endif
>  #else
>  #define BPF_PROG_PACK_SIZE PAGE_SIZE
>  #endif

I have sent a patch with the above:
https://lore.kernel.org/all/20240308120712.88122-1-puranjay12@gmail.com/
Thanks for helping with this.

I have tested that this patch fixes this issue.

Thanks,
Puranjay