[LTP] [PATCH] hugemmap41: Migrate ptrace-write-hugepage from libhugetlbfs v3

[LTP] [PATCH] hugemmap41: Migrate ptrace-write-hugepage from libhugetlbfs v3

[Pavithra]

This test verifies that ptrace POKEDATA and PEEKDATA operations work
correctly on hugepage-backed memory regions. The test creates a child
process that maps a hugepage, then the parent process uses ptrace to
attach to the child and perform write/read operations on the child's
hugepage memory.

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap41.c  | 140 ++++++++++++++++++
 3 files changed, 142 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 0896d3c94..14ca64018 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -36,6 +36,7 @@ hugemmap30 hugemmap30
 hugemmap31 hugemmap31
 hugemmap32 hugemmap32
 hugemmap34 hugemmap34
+hugemmap41 hugemmap41
 hugemmap05_1 hugemmap05 -m
 hugemmap05_2 hugemmap05 -s
 hugemmap05_3 hugemmap05 -s -m
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index b4455de51..4bd7481b0 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -36,6 +36,7 @@
 /hugetlb/hugemmap/hugemmap31
 /hugetlb/hugemmap/hugemmap32
 /hugetlb/hugemmap/hugemmap34
+/hugetlb/hugemmap/hugemmap41
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c
new file mode 100644
index 000000000..98b9909be
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c
@@ -0,0 +1,140 @@
+// 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 ptrace write to hugepage memory.
+ *
+ * This test verifies that ptrace POKEDATA and PEEKDATA work correctly
+ * on hugepage-backed memory regions. A child process maps a hugepage,
+ * and the parent uses ptrace to write and read data from the child's
+ * hugepage memory, ensuring that ptrace operations function properly
+ * with hugepage mappings.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "tst_test.h"
+#include "hugetlb.h"
+
+#define CONST	0xdeadbeefL
+#define MNTPOINT "hugetlbfs/"
+
+static long hpage_size;
+static int fd = -1;
+
+static void child(int hugefd, int pipefd[2])
+{
+	void *p;
+
+	SAFE_CLOSE(pipefd[0]);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+		      hugefd, 0);
+
+	memset(p, 0, hpage_size);
+
+	tst_res(TINFO, "Child mapped data at %p", p);
+
+	SAFE_WRITE(SAFE_WRITE_ALL, pipefd[1], &p, sizeof(p));
+	SAFE_CLOSE(pipefd[1]);
+
+	pause();
+	/* Child is killed by parent via PTRACE_KILL, so cleanup is not reached */
+}
+
+static void do_poke(pid_t pid, void *p)
+{
+	long err;
+
+	tst_res(TINFO, "Poking at %p...", p);
+	err = ptrace(PTRACE_POKEDATA, pid, p, (void *)CONST);
+	if (err)
+		tst_brk(TFAIL | TERRNO, "ptrace(POKEDATA) failed");
+
+	tst_res(TINFO, "Peeking at %p...", p);
+	errno = 0;
+	err = ptrace(PTRACE_PEEKDATA, pid, p, NULL);
+	if (err == -1 && errno)
+		tst_brk(TFAIL | TERRNO, "ptrace(PEEKDATA) failed");
+
+	if (err != CONST)
+		tst_brk(TFAIL, "Value mismatch: got %lx, expected %lx", err, CONST);
+}
+
+static void run_test(void)
+{
+	int pipefd[2];
+	long err;
+	pid_t cpid;
+	void *p;
+	int status;
+
+	fd = tst_creat_unlinked(MNTPOINT, 0, 0600);
+
+	SAFE_PIPE(pipefd);
+
+	cpid = SAFE_FORK();
+
+	if (cpid == 0) {
+		child(fd, pipefd);
+		exit(0);
+	}
+
+	/* Parent */
+	SAFE_CLOSE(pipefd[1]);
+	SAFE_READ(1, pipefd[0], &p, sizeof(p));
+	SAFE_CLOSE(pipefd[0]);
+
+	tst_res(TINFO, "Parent received address %p", p);
+
+	err = ptrace(PTRACE_ATTACH, cpid, NULL, NULL);
+	if (err)
+		tst_brk(TFAIL | TERRNO, "ptrace(ATTACH) failed");
+
+	TST_PROCESS_STATE_WAIT(cpid, 't', 0);
+
+	do_poke(cpid, p);
+	do_poke(cpid, p + getpagesize());
+
+	SAFE_PTRACE(PTRACE_KILL, cpid, NULL, NULL);
+	SAFE_WAITPID(cpid, &status, 0);
+
+	SAFE_CLOSE(fd);
+	fd = -1;
+
+	tst_res(TPASS, "ptrace write to hugepage succeeded");
+}
+
+static void setup(void)
+{
+	hpage_size = tst_get_hugepage_size();
+}
+
+static void cleanup(void)
+{
+	if (fd != -1)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.tags = (struct tst_tag[]) {
+		{"linux-git", "ebed4bfc8da8"},
+		{}
+	},
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.needs_hugetlbfs = 1,
+	.hugepages = {4, TST_NEEDS},
+	.forks_child = 1,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+};
-- 
2.53.0


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Re: [LTP] hugemmap41: Migrate ptrace-write-hugepage from libhugetlbfs v3

[linuxtestproject.agent]

Hi Pavithra,

On Sat, Apr 4 2026, Pavithra wrote:
> hugemmap41: Migrate ptrace-write-hugepage from libhugetlbfs v3

The subject ends with "v3". Is that a patch revision marker that did
not get stripped before committing? If it refers to something like a
libhugetlbfs variant, please rephrase the subject to make that clear.

> +/*
> + * Test ptrace write to hugepage memory.
> + *
> + * This test verifies that ptrace POKEDATA and PEEKDATA work correctly
> + * on hugepage-backed memory regions. A child process maps a hugepage,
> + * and the parent uses ptrace to write and read data from the child's
> + * hugepage memory, ensuring that ptrace operations function properly
> + * with hugepage mappings.
> + */

The description block must open with "/*\" (backslash after the star)
so it is recognized as RST and rendered in the LTP test catalog.

Also, .needs_root = 1 is set but the block does not explain why root
is required. Ground Rule 4 requires documenting the reason here (e.g.,
ptrace(PTRACE_ATTACH) requires CAP_SYS_PTRACE when ptrace_scope > 1,
or the hugetlbfs mount operations need root).

> +	SAFE_PTRACE(PTRACE_KILL, cpid, NULL, NULL);
> +	SAFE_WAITPID(cpid, &status, 0);

PTRACE_KILL is deprecated. From ptrace(2): "This operation is
deprecated; do not use it!" The recommended replacement is to deliver
SIGKILL directly via kill(cpid, SIGKILL) and then wait for it.

Verdict - Needs revision

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Note:

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 suggestions.

Regards,
LTP AI Reviewer

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