[PATCH bpf-next v2] bpf: hardcode BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes()

[PATCH bpf-next v2] bpf: hardcode BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes()

[Puranjay Mohan]

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 size for allocations done through
the prog pack allocator. On most architectures, PMD_SIZE will be equal
to 2MB in case of 4KB pages and will be greater than 2MB for bigger page
sizes.

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/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202403092219.dhgcuz2G-lkp@intel.com/
Suggested-by: Song Liu <song@kernel.org>
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
---
 kernel/bpf/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 134b7979f537..a8007f7f706d 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -893,7 +893,12 @@ 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. Hardcode BPF_PROG_PACK_SIZE to
+ * 2MiB * num_possible_nodes(). On most architectures PMD_SIZE will be
+ * greater than or equal to 2MB.
+ */
+#define BPF_PROG_PACK_SIZE (SZ_2M * num_possible_nodes())
 #else
 #define BPF_PROG_PACK_SIZE PAGE_SIZE
 #endif
-- 
2.40.1

Re: [PATCH bpf-next v2] bpf: hardcode BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Mon, 11 Mar 2024 12:27:22 +0000 you 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 size for allocations done through
> the prog pack allocator. On most architectures, PMD_SIZE will be equal
> to 2MB in case of 4KB pages and will be greater than 2MB for bigger page
> sizes.
> 
> [...]

Here is the summary with links:
  - [bpf-next,v2] bpf: hardcode BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes()
    https://git.kernel.org/bpf/bpf-next/c/d6170e4aaf86

You are awesome, thank you!
-- 
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