linux-kernel - [PATCH 6.6 340/638] bpf: hardcode BPF_PROG_PACK_SIZE to 2MB * num_possible

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Date: Sun, 24 Mar 2024 18:56:17 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Puranjay Mohan <puranjay12@...il.com>,
	"kernelci.org bot" <bot@...nelci.org>,
	kernel test robot <lkp@...el.com>,
	Song Liu <song@...nel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 6.6 340/638] bpf: hardcode BPF_PROG_PACK_SIZE to 2MB * num_possible_nodes()

From: Puranjay Mohan <puranjay12@...il.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@...nelci.org>
Closes: https://lore.kernel.org/all/7e216c88-77ee-47b8-becc-a0f780868d3c@sirena.org.uk/
Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202403092219.dhgcuz2G-lkp@intel.com/
Suggested-by: Song Liu <song@...nel.org>
Signed-off-by: Puranjay Mohan <puranjay12@...il.com>
Message-ID: <20240311122722.86232-1-puranjay12@...il.com>
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.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 5d1efe5200ba3..1333273a71ded 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -863,7 +863,12 @@ 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