[LTP] [PATCH] Fix hugeshmat05 test failure on lpar with 1GB hugepages.

[LTP] [PATCH] Fix hugeshmat05 test failure on lpar with 1GB hugepages.

[Pavithra]

Modified the test to detect large hugepage sizes (≥1GB) and adjust test sizes accordingly.

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
 .../mem/hugetlb/hugeshmat/hugeshmat05.c       | 30 ++++++++++++++-----
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/testcases/kernel/mem/hugetlb/hugeshmat/hugeshmat05.c b/testcases/kernel/mem/hugetlb/hugeshmat/hugeshmat05.c
index 3b2ae351c..c1e34f999 100644
--- a/testcases/kernel/mem/hugetlb/hugeshmat/hugeshmat05.c
+++ b/testcases/kernel/mem/hugetlb/hugeshmat/hugeshmat05.c
@@ -37,9 +37,13 @@ void setup(void)
 {
 	page_size = getpagesize();
 	hpage_size = SAFE_READ_MEMINFO("Hugepagesize:") * 1024;
+
+	tst_res(TINFO, "Page size: %ld bytes", page_size);
+	tst_res(TINFO, "Hugepage size: %ld bytes (%ld MB)",
+		hpage_size, hpage_size / (1024 * 1024));
 }
 
-void shm_test(int size)
+void shm_test(long size)
 {
 	int shmid;
 	char *shmaddr;
@@ -56,7 +60,7 @@ void shm_test(int size)
 	}
 
 	shmaddr[0] = 1;
-	tst_res(TINFO, "allocated %d huge bytes", size);
+	tst_res(TINFO, "allocated %ld huge bytes", size);
 
 	if (shmdt((const void *)shmaddr) != 0) {
 		shmctl(shmid, IPC_RMID, NULL);
@@ -69,13 +73,23 @@ void shm_test(int size)
 static void test_hugeshmat(void)
 {
 	unsigned int i;
+	long multiplier;
+	long tst_sizes[4];
+
+	/*
+	 * For large hugepage sizes (e.g., 1GB), use N/2 multiplier to avoid
+	 * excessive memory requirements (4GB for N=4 with 1GB pages) while
+	 * still testing alignment boundary conditions with multiple pages.
+	 */
+	if (hpage_size >= 1024 * 1024 * 1024)
+		multiplier = N / 2;
+	else
+		multiplier = N;
 
-	const int tst_sizes[] = {
-		N * hpage_size - page_size,
-		N * hpage_size - page_size - 1,
-		hpage_size,
-		hpage_size + 1
-	};
+	tst_sizes[0] = multiplier * hpage_size - page_size;
+	tst_sizes[1] = multiplier * hpage_size - page_size - 1;
+	tst_sizes[2] = hpage_size;
+	tst_sizes[3] = hpage_size + 1;
 
 	for (i = 0; i < ARRAY_SIZE(tst_sizes); ++i)
 		shm_test(tst_sizes[i]);
-- 
2.53.0


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Re: [LTP] Fix hugeshmat05 test failure on lpar with 1GB hugepages.

[linuxtestproject.agent]

Hi Pavithra,

On Mon, 20 Apr 2026, Pavithra wrote:
> Fix hugeshmat05 test failure on lpar with 1GB hugepages.
>
> Modified the test to detect large hugepage sizes (≥1GB) and adjust test sizes accordingly.

The commit body describes what changed but not why the test was failing.
Is shmget failing because N*hpage_size=4GB exceeds what the LPAR can
allocate in one call, or is it a pool exhaustion issue? Please document
the root cause in the commit message.

> +       if (hpage_size >= 1024 * 1024 * 1024)
> +               multiplier = N / 2;
> +       else
> +               multiplier = N;

With multiplier=2 for 1GB pages the test needs at most 2 hugepages at
peak, but .hugepages = {N+1, TST_NEEDS} still requires 5 free 1GB pages
(5 GB). On an LPAR with 2–4 free 1GB hugepages the test still cannot
run. Update .hugepages to match the reduced requirement.

---
Note:

Our agent completed the review of the patch. The agent can sometimes
produce false positives although often its findings are genuine. If you
find issues with the review, please comment this email or ignore the
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Regards,
LTP AI Reviewer

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