[PATCH] selftests/mm: hugetlb-read-hwpoison: add setup of HugeTLB pages

[Jaeyeon Lee <jaeyeon.lee.dev@gmail.com>]

Every test is expected to reserve the HugeTLB pages it needs.
hugetlb-read-hwpoison was not converted, so on a system without
pre-reserved huge pages the MAP_POPULATE mmap() fails with ENOMEM and
every test case is skipped.

Reserve the pages with hugetlb_setup_default(). Each chunk size runs two
HWPOISON tests and a poisoned huge page can't be reused, so reserve two
pages per chunk size. The pool size is restored on exit. The poisoned
pages remain allocated until reboot.

With the patch, all 12 cases pass on a system with no huge pages
reserved (tested on Fedora, x86_64, CONFIG_MEMORY_FAILURE=y).

Assisted-by: LLM
Signed-off-by: Jaeyeon Lee <jaeyeon.lee.dev@gmail.com>
---
 tools/testing/selftests/mm/hugetlb-read-hwpoison.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/testing/selftests/mm/hugetlb-read-hwpoison.c b/tools/testing/selftests/mm/hugetlb-read-hwpoison.c
index 70b24e3660c4..31748a24448f 100644
--- a/tools/testing/selftests/mm/hugetlb-read-hwpoison.c
+++ b/tools/testing/selftests/mm/hugetlb-read-hwpoison.c
@@ -13,6 +13,7 @@
 #include <signal.h>
 
 #include "kselftest.h"
+#include "vm_util.h"
 
 #define MAX_WRITE_READ_CHUNK_SIZE (getpagesize() * 16)
 #define MAX(a, b) (((a) > (b)) ? (a) : (b))
@@ -281,6 +282,13 @@ int main(void)
 	size_t i;
 
 	ksft_print_header();
+
+	if (!hugetlb_available())
+		ksft_exit_skip("HugeTLB is not available\n");
+
+	if (!hugetlb_setup_default(ARRAY_SIZE(wr_chunk_sizes) * 2))
+		ksft_exit_skip("Not enough free huge pages\n");
+
 	ksft_set_plan(ARRAY_SIZE(wr_chunk_sizes) * 3);
 
 	signal(SIGBUS, sigbus_handler);
-- 
2.43.0