From: Song Liu <song@kernel.org>
To: Puranjay Mohan <puranjay12@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>,
Yonghong Song <yonghong.song@linux.dev>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next] bpf: cap BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes()
Date: Fri, 8 Mar 2024 08:55:15 -0800 [thread overview]
Message-ID: <CAPhsuW7Do8c8cA6rVykhVnFRgKA0s6nO8JyGXkEB7gm94KR7Mw@mail.gmail.com> (raw)
In-Reply-To: <20240308120712.88122-1-puranjay12@gmail.com>
On Fri, Mar 8, 2024 at 4:07 AM Puranjay Mohan <puranjay12@gmail.com> wrote:
>
> On some architectures like ARM64, PMD_SIZE can be really large in some
> configurations. Like with CONFIG_ARM64_64K_PAGES=y the PMD_SIZE is
> 512MB.
>
> Use 2MB * num_possible_nodes() as the upper limit for allocations done
> through the prog pack allocator.
>
> Fixes: ea2babac63d4 ("bpf: Simplify bpf_prog_pack_[size|mask]")
> Reported-by: "kernelci.org bot" <bot@kernelci.org>
> Closes: https://lore.kernel.org/all/7e216c88-77ee-47b8-becc-a0f780868d3c@sirena.org.uk/
> Suggested-by: Song Liu <song@kernel.org>
> Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
> ---
> kernel/bpf/core.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 134b7979f537..83a3b6964e54 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -893,8 +893,17 @@ static LIST_HEAD(pack_list);
> * CONFIG_MMU=n. Use PAGE_SIZE in these cases.
> */
> #ifdef PMD_SIZE
> +/*
> + * 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().
> + */
In BPF code, we prefer a different style of multiple line comments:
/* 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().
*/
Other than this, this looks good to me.
Acked-by: Song Liu <song@kernel.org>
Thanks,
Song
> +#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
next prev parent reply other threads:[~2024-03-08 16:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-08 12:07 [PATCH bpf-next] bpf: cap BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes() Puranjay Mohan
2024-03-08 16:55 ` Song Liu [this message]
2024-03-08 23:08 ` Alexei Starovoitov
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