linux-kernel - [PATCH v6 bpf-next 5/5] bpf: simplify select_bpf_prog_pack

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Date:   Thu, 7 Jul 2022 15:35:46 -0700
From:   Song Liu <song@...nel.org>
To:     <bpf@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>
CC:     <daniel@...earbox.net>, <kernel-team@...com>, <x86@...nel.org>,
        <dave.hansen@...ux.intel.com>, <rick.p.edgecombe@...el.com>,
        <mcgrof@...nel.org>, Song Liu <song@...nel.org>
Subject: [PATCH v6 bpf-next 5/5] bpf: simplify select_bpf_prog_pack_size

Use huge_vmalloc_supported to simplify select_bpf_prog_pack_size, so that
we don't allocate some huge pages and free them immediately.

Suggested-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
Signed-off-by: Song Liu <song@...nel.org>
---
 kernel/bpf/core.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index d1f32ac354d3..e1f8d36fb95c 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -857,22 +857,15 @@ static LIST_HEAD(pack_list);
 static size_t select_bpf_prog_pack_size(void)
 {
 	size_t size;
-	void *ptr;
-
-	size = BPF_HPAGE_SIZE * num_online_nodes();
-	ptr = module_alloc_huge(size);
 
-	/* Test whether we can get huge pages. If not just use PAGE_SIZE
-	 * packs.
-	 */
-	if (!ptr || !is_vm_area_hugepages(ptr)) {
+	if (huge_vmalloc_supported()) {
+		size = BPF_HPAGE_SIZE * num_online_nodes();
+		bpf_prog_pack_mask = BPF_HPAGE_MASK;
+	} else {
 		size = PAGE_SIZE;
 		bpf_prog_pack_mask = PAGE_MASK;
-	} else {
-		bpf_prog_pack_mask = BPF_HPAGE_MASK;
 	}
 
-	vfree(ptr);
 	return size;
 }
 
-- 
2.30.2