[PATCH bpf-next v4 4/7] selftests/bpf: Test large allocations for both sleepable/nonsleepable arena users

[Emil Tsalapatis <emil@etsalapatis.com>]

We have relaxed the limitation of 1024-page batches for both sleepable
and nonsleepable arena allocations by removing the intermediate page
array. Add a test to confirm that large allocations succeed for both.

Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
---
 .../bpf/progs/verifier_arena_large.c          | 64 +++++++++++++++----
 1 file changed, 50 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/verifier_arena_large.c b/tools/testing/selftests/bpf/progs/verifier_arena_large.c
index 6ab8730d4878..dbdea14ca76f 100644
--- a/tools/testing/selftests/bpf/progs/verifier_arena_large.c
+++ b/tools/testing/selftests/bpf/progs/verifier_arena_large.c
@@ -10,6 +10,9 @@
 #include <bpf_arena_common.h>
 
 #define ARENA_SIZE (1ull << 32)
+#define LARGE_PAGE_CNT 1025
+
+volatile int zero = 0;
 
 struct {
 	__uint(type, BPF_MAP_TYPE_ARENA);
@@ -284,6 +287,7 @@ int big_alloc2(void *ctx)
 	return 0;
 }
 
+/* Nonsleepable because it binds to a socket program. */
 SEC("socket")
 __success __retval(0)
 int big_alloc3(void *ctx)
@@ -291,24 +295,56 @@ int big_alloc3(void *ctx)
 #if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
 	char __arena *pages;
 	u64 i;
+	int err = 0;
 
-	/*
-	 * Allocate 2051 pages in one go to check how kmalloc_nolock() handles large requests.
-	 * Since kmalloc_nolock() can allocate up to 1024 struct page * at a time, this call should
-	 * result in three batches: two batches of 1024 pages each, followed by a final batch of 3
-	 * pages.
-	 */
-	pages = bpf_arena_alloc_pages(&arena, NULL, 2051, NUMA_NO_NODE, 0);
+	/* Verify that a nonsleepable allocation larger than 1024 pages succeeds. */
+	pages = bpf_arena_alloc_pages(&arena, NULL, LARGE_PAGE_CNT, NUMA_NO_NODE, 0);
 	if (!pages)
-		return 0;
+		return 1;
+
+	for (i = zero; i < LARGE_PAGE_CNT && can_loop; i++)
+		pages[i * PAGE_SIZE] = 123;
+
+	for (i = zero; i < LARGE_PAGE_CNT && can_loop; i++) {
+		if (pages[i * PAGE_SIZE] == 123)
+			continue;
+		err = 2;
+		break;
+	}
+
+	bpf_arena_free_pages(&arena, pages, LARGE_PAGE_CNT);
+	return err;
+#endif
+	return 0;
+}
 
-	bpf_for(i, 0, 2051)
-			pages[i * PAGE_SIZE] = 123;
-	bpf_for(i, 0, 2051)
-			if (pages[i * PAGE_SIZE] != 123)
-				return i;
+/* SYSCALL programs are always sleepable. */
+SEC("syscall")
+__success __retval(0)
+int big_alloc4(void *ctx)
+{
+#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
+	char __arena *pages;
+	u64 i;
+	int err = 0;
+
+	/* Verify that a sleepable allocation larger than 1024 pages succeeds. */
+	pages = bpf_arena_alloc_pages(&arena, NULL, LARGE_PAGE_CNT, NUMA_NO_NODE, 0);
+	if (!pages)
+		return 1;
+
+	for (i = zero; i < LARGE_PAGE_CNT && can_loop; i++)
+		pages[i * PAGE_SIZE] = 123;
+
+	for (i = zero; i < LARGE_PAGE_CNT && can_loop; i++) {
+		if (pages[i * PAGE_SIZE] == 123)
+			continue;
+		err = 2;
+		break;
+	}
 
-	bpf_arena_free_pages(&arena, pages, 2051);
+	bpf_arena_free_pages(&arena, pages, LARGE_PAGE_CNT);
+	return err;
 #endif
 	return 0;
 }
-- 
2.52.0