[LTP] [PATCH v8] hugetlb/hugeshmget: Add hugeshmget07 to test SHM_HUGETLB with /dev/zero read

[Pavithra <pavrampu@linux.ibm.com>]

Test that a hugepage-backed shared memory segment can be created,
attached, read into via /dev/zero, detached and removed without
errors.

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
v7 -> v8:
- Move test from syscalls/shmget/shmget07.c to hugetlb/hugeshmget/hugeshmget07.c
- Remove redundant #include "tst_hugepage.h"
- Rename raw_fd to zero_fd
- Replace TEST()/if/tst_res() block with TST_EXP_VAL()
Link to v7: https://lore.kernel.org/ltp/20260919151602.1039825-1-pavrampu@linux.ibm.com/
---
 runtest/hugetlb                               |  1 +
 testcases/kernel/mem/.gitignore               |  1 +
 .../mem/hugetlb/hugeshmget/hugeshmget07.c     | 69 +++++++++++++++++++
 3 files changed, 71 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugeshmget/hugeshmget07.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 621c9718a..d090cddec 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -62,3 +62,4 @@ hugeshmget02 hugeshmget02 -i 10
 hugeshmget03 hugeshmget03 -i 10
 hugeshmget05 hugeshmget05 -i 10
 hugeshmget06 hugeshmget06 -i 10
+hugeshmget07 hugeshmget07 -i 10
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index 9e706e1c8..67f9c23a5 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -55,6 +55,7 @@
 /hugetlb/hugeshmget/hugeshmget03
 /hugetlb/hugeshmget/hugeshmget05
 /hugetlb/hugeshmget/hugeshmget06
+/hugetlb/hugeshmget/hugeshmget07
 /ksm/ksm01
 /ksm/ksm02
 /ksm/ksm03
diff --git a/testcases/kernel/mem/hugetlb/hugeshmget/hugeshmget07.c b/testcases/kernel/mem/hugetlb/hugeshmget/hugeshmget07.c
new file mode 100644
index 000000000..1a85b87e4
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugeshmget/hugeshmget07.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2005-2006 David Gibson & Adam Litke, IBM Corporation.
+ * Copyright (c) 2026 Pavithra <pavrampu@linux.ibm.com>
+ */
+
+/*\
+ * Test :manpage:`shmget(2)` shared memory segment with hugepages.
+ *
+ * A hugepage-backed shared memory segment is created and attached to
+ * the process address space. The test reads one hugepage at a time
+ * from ``/dev/zero`` directly into the shared memory region,
+ * verifying that each read delivers the full hugepage worth of data.
+ * The segment is then detached and removed.
+ *
+ * Requires root for :manpage:`shmget(2)` with ``SHM_HUGETLB``.
+ */
+
+#include "tst_test.h"
+#include "tst_safe_sysv_ipc.h"
+
+#define NR_HUGEPAGES 2
+
+static int shmid = -1;
+static long hpage_size;
+
+static void setup(void)
+{
+	hpage_size = tst_get_hugepage_size();
+}
+
+static void cleanup(void)
+{
+	if (shmid >= 0)
+		SAFE_SHMCTL(shmid, IPC_RMID, NULL);
+}
+
+static void run_test(void)
+{
+	size_t i;
+	size_t size = hpage_size * NR_HUGEPAGES;
+	char *shmaddr;
+	int zero_fd;
+
+	zero_fd = SAFE_OPEN("/dev/zero", O_RDONLY);
+
+	shmid = SAFE_SHMGET(IPC_PRIVATE, size, SHM_HUGETLB | SHM_R | SHM_W);
+
+	shmaddr = SAFE_SHMAT(shmid, 0, SHM_RND);
+	tst_res(TINFO, "shmaddr: %p", shmaddr);
+
+	for (i = 0; i < size; i += hpage_size) {
+		TST_EXP_VAL(read(zero_fd, shmaddr + i, hpage_size),
+			(ssize_t)hpage_size);
+	}
+
+	SAFE_CLOSE(zero_fd);
+	SAFE_SHMDT(shmaddr);
+	SAFE_SHMCTL(shmid, IPC_RMID, NULL);
+	shmid = -1;
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+	.hugepages = {NR_HUGEPAGES, TST_NEEDS},
+};
-- 
2.55.0


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