[LTP] [PATCH v7] syscalls/shmget: Add shmget07 to test SHM_HUGETLB with raw device read

[Pavithra]

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

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
v6 -> v7:
- Fix read() destination not advancing per iteration (shmaddr ->
  shmaddr + i)
- Add SAFE_SHMCTL(IPC_RMID) and reset shmid = -1 at end of run_test()
  to fix hugepage pool leak between iterations (ENOMEM on -i 2)
- Add SAFE_CLOSE(raw_fd) to fix fd leak
- Use NR_HUGEPAGES in .hugepages struct instead of magic literal 2
Link to v6: https://lore.kernel.org/ltp/20260311070235.206921-1-pavrampu@linux.ibm.com/
---
 runtest/syscalls                            |  1 +
 testcases/kernel/syscalls/shmget/.gitignore |  1 +
 testcases/kernel/syscalls/shmget/shmget07.c | 76 +++++++++++++++++++++
 3 files changed, 78 insertions(+)
 create mode 100644 testcases/kernel/syscalls/shmget/shmget07.c

diff --git a/runtest/syscalls b/runtest/syscalls
index accdf2df9..e6b0f3f0b 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1593,6 +1593,7 @@ shmget03 shmget03
 shmget04 shmget04
 shmget05 shmget05
 shmget06 shmget06
+shmget07 shmget07
 
 shutdown01 shutdown01
 shutdown02 shutdown02
diff --git a/testcases/kernel/syscalls/shmget/.gitignore b/testcases/kernel/syscalls/shmget/.gitignore
index 768d1c69d..23ba002b5 100644
--- a/testcases/kernel/syscalls/shmget/.gitignore
+++ b/testcases/kernel/syscalls/shmget/.gitignore
@@ -3,3 +3,4 @@
 /shmget04
 /shmget05
 /shmget06
+/shmget07
diff --git a/testcases/kernel/syscalls/shmget/shmget07.c b/testcases/kernel/syscalls/shmget/shmget07.c
new file mode 100644
index 000000000..f862f1dd5
--- /dev/null
+++ b/testcases/kernel/syscalls/shmget/shmget07.c
@@ -0,0 +1,76 @@
+// 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 :file:`/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_hugepage.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 raw_fd;
+
+	raw_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);
+
+	/* Read a page from device and write to shm segment */
+
+	for (i = 0; i < size; i += hpage_size) {
+		TEST(read(raw_fd, shmaddr + i, hpage_size));
+		if (TST_RET != hpage_size) {
+			tst_res(TFAIL | TERRNO, "Can't read full page from raw device!");
+			break;
+		}
+		tst_res(TPASS, "Read full page from raw device");
+	}
+
+	SAFE_CLOSE(raw_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