Received-SPF: pass (google.com: domain of linux-kernel+bounces-97686-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:40f1:3f00::1 as permitted sender) client-ip=2604:1380:40f1:3f00::1;
Precedence: bulk
MIME-Version: 1.0
References: <20240308120712.88122-1-puranjay12@gmail.com> <CAPhsuW7Do8c8cA6rVykhVnFRgKA0s6nO8JyGXkEB7gm94KR7Mw@mail.gmail.com>
In-Reply-To: <CAPhsuW7Do8c8cA6rVykhVnFRgKA0s6nO8JyGXkEB7gm94KR7Mw@mail.gmail.com>
From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date: Fri, 8 Mar 2024 15:08:15 -0800
Message-ID: <CAADnVQJkcF82ekPXK1ox0sW5x-P67wbL_2uiivXXxBP8zFrVKQ@mail.gmail.com>
Subject: Re: [PATCH bpf-next] bpf: cap BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes()
To: Song Liu <song@kernel.org>
Cc: Puranjay Mohan <puranjay12@gmail.com>, 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 <bpf@vger.kernel.org>, 
	LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Fri, Mar 8, 2024 at 8:55=E2=80=AFAM Song Liu <song@kernel.org> wrote:
>
> On Fri, Mar 8, 2024 at 4:07=E2=80=AFAM Puranjay Mohan <puranjay12@gmail.c=
om> wrote:
> >
> > On some architectures like ARM64, PMD_SIZE can be really large in some
> > configurations. Like with CONFIG_ARM64_64K_PAGES=3Dy 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-a0f780868d3=
c@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=3Dn. 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 t=
o
> > + * 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().
>  */

Fixed up while applying. Thanks everyone.