[LTP] [PATCH v2 02/13] Hugetlb: Migrating libhugetlbfs mmap-cow

[Tarun Sahu]

Migrating the libhugetlbfs/testcases/mmap-cow.c test

Test Description: Tests copy-on-write semantics of large pages where a
number of threads map the same file with the MAP_PRIVATE flag. The threads
then write into their copy of the mapping and recheck the contents to
ensure they were not corrupted by the other threads.

Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
Reviewed-by: Li Wang <liwang@redhat.com>

---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap21.c  | 116 ++++++++++++++++++
 3 files changed, 118 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap21.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 2dffa8421..71b4d57e4 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -22,6 +22,7 @@ hugemmap17 hugemmap17
 hugemmap18 hugemmap18
 hugemmap19 hugemmap19
 hugemmap20 hugemmap20
+hugemmap21 hugemmap21
 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 dfd372892..74edfa392 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -21,6 +21,7 @@
 /hugetlb/hugemmap/hugemmap18
 /hugetlb/hugemmap/hugemmap19
 /hugetlb/hugemmap/hugemmap20
+/hugetlb/hugemmap/hugemmap21
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap21.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap21.c
new file mode 100644
index 000000000..ce3c5866e
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap21.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright (C) 2005-2006 IBM Corporation.
+ * Author: David Gibson & Adam Litke
+ */
+
+/*\
+ * [Description]
+ *
+ * Tests copy-on-write semantics of large pages where a number of threads
+ * map the same file with the MAP_PRIVATE flag. The threads then write
+ * into their copy of the mapping and recheck the contents to ensure they
+ * were not corrupted by the other threads.
+ */
+
+#include "hugetlb.h"
+
+#define THREADS 5
+#define NR_HUGEPAGES 6
+#define MNTPOINT "hugetlbfs/"
+
+static int fd = -1;
+static long hpage_size;
+
+static void do_work(int thread, size_t size, int fd)
+{
+	char *addr;
+	size_t i;
+	char pattern = thread+65;
+
+	addr = SAFE_MMAP(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+
+	tst_res(TINFO, "Thread %d (pid %d): Mapped at address %p",
+	       thread, getpid(), addr);
+
+	for (i = 0; i < size; i++)
+		memcpy((char *)addr+i, &pattern, 1);
+
+	if (msync(addr, size, MS_SYNC))
+		tst_brk(TBROK|TERRNO, "Thread %d (pid %d): msync() failed",
+				thread, getpid());
+
+	for (i = 0; i < size; i++)
+		if (addr[i] != pattern) {
+			tst_res(TFAIL, "thread %d (pid: %d): Corruption at %p; "
+				   "Got %c, Expected %c", thread, getpid(),
+				   &addr[i], addr[i], pattern);
+			goto cleanup;
+		}
+	tst_res(TINFO, "Thread %d (pid %d): Pattern verified",
+			thread, getpid());
+
+cleanup:
+	SAFE_MUNMAP(addr, size);
+	exit(0);
+}
+
+static void run_test(void)
+{
+	char *addr;
+	size_t size, itr;
+	int i, pid;
+	pid_t *wait_list;
+
+	wait_list = SAFE_MALLOC(THREADS * sizeof(pid_t));
+	size = (NR_HUGEPAGES / (THREADS+1)) * hpage_size;
+
+
+	/* First, mmap the file with MAP_SHARED and fill with data
+	 * If this is not done, then the fault handler will not be
+	 * called in the kernel since private mappings will be
+	 * created for the children at prefault time.
+	 */
+	addr = SAFE_MMAP(NULL, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+
+	for (itr = 0; itr < size; itr += 8)
+		memcpy(addr+itr, "deadbeef", 8);
+
+	for (i = 0; i < THREADS; i++) {
+		pid = SAFE_FORK();
+
+		if (pid == 0)
+			do_work(i, size, fd);
+
+		wait_list[i] = pid;
+	}
+	tst_reap_children();
+
+	SAFE_MUNMAP(addr, size);
+	free(wait_list);
+	tst_res(TPASS, "mmap COW working as expected.");
+}
+
+static void setup(void)
+{
+	hpage_size = tst_get_hugepage_size();
+	fd = tst_creat_unlinked(MNTPOINT, 0);
+}
+
+static void cleanup(void)
+{
+	if (fd >= 1)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.needs_hugetlbfs = 1,
+	.needs_tmpdir = 1,
+	.forks_child = 1,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+	.hugepages = {NR_HUGEPAGES, TST_NEEDS},
+};
-- 
2.31.1