[PATCH 6.8 346/715] bpf: hardcode BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes()

Sasha Levin
2024-03-24T22:40:38Z

From: Puranjay Mohan <puranjay12@gmail.com>

[ Upstream commit d6170e4aaf86424c24ce06e355b4573daa891b17 ]

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>
Message-ID: <20240311122722.86232-1-puranjay12@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 ea6843be2616c..026627226ec48 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -888,7 +888,12 @@ 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
--
2.43.0