[LTP] [PATCH v3 1/2] Add process_mrelease01 test

[Andrea Cervesato]

From: Andrea Cervesato <andrea.cervesato@suse.com>

Verify process_mrelease() releases memory from a dying process.
If the child process terminates before the syscall can reap its
address space, retry with larger memory allocations to extend
teardown duration.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 runtest/syscalls                                   |  2 +
 .../kernel/syscalls/process_mrelease/.gitignore    |  1 +
 .../kernel/syscalls/process_mrelease/Makefile      |  7 ++
 .../syscalls/process_mrelease/process_mrelease01.c | 94 ++++++++++++++++++++++
 4 files changed, 104 insertions(+)

diff --git a/runtest/syscalls b/runtest/syscalls
index 737c63e31..cfe76efca 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1151,6 +1151,8 @@ preadv203_64 preadv203_64
 
 profil01 profil01
 
+process_mrelease01 process_mrelease01
+
 process_vm_readv01 process_vm01 -r
 process_vm_readv02 process_vm_readv02
 process_vm_readv03 process_vm_readv03
diff --git a/testcases/kernel/syscalls/process_mrelease/.gitignore b/testcases/kernel/syscalls/process_mrelease/.gitignore
new file mode 100644
index 000000000..673983858
--- /dev/null
+++ b/testcases/kernel/syscalls/process_mrelease/.gitignore
@@ -0,0 +1 @@
+/process_mrelease01
diff --git a/testcases/kernel/syscalls/process_mrelease/Makefile b/testcases/kernel/syscalls/process_mrelease/Makefile
new file mode 100644
index 000000000..8cf1b9024
--- /dev/null
+++ b/testcases/kernel/syscalls/process_mrelease/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (C) 2024 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
+
+top_srcdir		?= ../../../..
+
+include $(top_srcdir)/include/mk/testcases.mk
+include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/syscalls/process_mrelease/process_mrelease01.c b/testcases/kernel/syscalls/process_mrelease/process_mrelease01.c
new file mode 100644
index 000000000..37001e846
--- /dev/null
+++ b/testcases/kernel/syscalls/process_mrelease/process_mrelease01.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2024 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
+ */
+
+/*\
+ * Test verifies that :manpage:`process_mrelease(2)` syscall releases memory
+ * from a killed process with pending memory allocations.
+ *
+ * [Algorithm]
+ *
+ * - Spawn a child process allocating and dirtying anonymous memory
+ * - Wait until the child is ready via checkpoints
+ * - Obtain child's pidfd and send SIGKILL to the child
+ * - Invoke process_mrelease(pidfd, 0)
+ * - If process_mrelease() fails with ESRCH (child terminated too fast),
+ *   double the allocation size and retry
+ * - Check that process_mrelease() succeeds
+ */
+
+#include "tst_test.h"
+#include "lapi/syscalls.h"
+
+#define CHUNK (1 * TST_MB)
+#define MAX_SIZE_MB (1024 * TST_MB)
+
+static void do_child(size_t size)
+{
+	void *mem;
+
+	tst_res(TINFO, "Child: allocate %zu MB", size / TST_MB);
+
+	mem = SAFE_MMAP(NULL,
+		size,
+		PROT_READ | PROT_WRITE,
+		MAP_PRIVATE | MAP_ANON,
+		-1, 0);
+
+	memset(mem, 0, size);
+
+	TST_CHECKPOINT_WAKE_AND_WAIT(0);
+
+	SAFE_MUNMAP(mem, size);
+}
+
+static void run(void)
+{
+	size_t mem_size;
+	pid_t pid;
+	int pidfd;
+	int status;
+
+	for (mem_size = CHUNK; mem_size <= MAX_SIZE_MB; mem_size *= 2) {
+		pid = SAFE_FORK();
+		if (!pid) {
+			do_child(mem_size);
+			exit(0);
+		}
+
+		TST_CHECKPOINT_WAIT(0);
+
+		pidfd = SAFE_PIDFD_OPEN(pid, 0);
+
+		SAFE_KILL(pid, SIGKILL);
+
+		TEST(tst_syscall(__NR_process_mrelease, pidfd, 0));
+
+		SAFE_WAITPID(pid, &status, 0);
+		SAFE_CLOSE(pidfd);
+
+		if (TST_RET == 0) {
+			tst_res(TPASS, "process_mrelease() passed with %zu MB",
+				mem_size / TST_MB);
+			return;
+		}
+
+		if (TST_ERR != ESRCH) {
+			tst_res(TFAIL | TTERRNO, "process_mrelease() failed");
+			return;
+		}
+
+		tst_res(TINFO,
+			"Child terminated before process_mrelease(). Increasing memory size and retrying");
+	}
+
+	tst_res(TFAIL, "All process_mrelease() attempts failed with ESRCH");
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.forks_child = 1,
+	.min_kver = "5.15",
+	.needs_checkpoints = 1,
+};

-- 
2.51.0