[LTP] [PATCH 0/3] Hugetlb:Migrating the libhugetlbfs tests

[LTP] [PATCH 0/3] Hugetlb:Migrating the libhugetlbfs tests

[Tarun Sahu]

Hi,
Libhugetlbfs is not being maintained actively, and some distro is dropping
support for it. There are some tests that are good for testing hugetlb
functionality in kernel.

As per previous dicussion in RFC[1], Here, this patch series consists
of hugetlb tests taken from libhugetlbfs modified to work in ltp
environment.

Based on suggestion[2], I am reposting the patches again. Also, I added
suggested changes by Cyril Hrubis and Li Wang[3].

ref:
1:https://lore.kernel.org/all/20220908173947.17956-1-tsahu@linux.ibm.com/
2:https://lore.kernel.org/all/87wn8xi61v.fsf@suse.de/
3:https://lore.kernel.org/all/20221016125731.249078-1-tsahu@linux.ibm.com/

Tarun Sahu (3):
  Hugetlb: Migrating libhugetlbfs brk_near_huge
  Hugetlb: Migrating libhugetlbfs chunk-overcommit
  Hugetlb: Migrating libhugetlbfs corrupt-by-cow-opt

 runtest/hugetlb                               |   3 +
 testcases/kernel/mem/.gitignore               |   3 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap07.c  | 156 ++++++++++++++++
 .../kernel/mem/hugetlb/hugemmap/hugemmap08.c  | 166 ++++++++++++++++++
 .../kernel/mem/hugetlb/hugemmap/hugemmap09.c  |  90 ++++++++++
 testcases/kernel/mem/hugetlb/lib/hugetlb.c    |  75 ++++++++
 testcases/kernel/mem/hugetlb/lib/hugetlb.h    |   5 +
 7 files changed, 498 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap08.c
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap09.c

-- 
2.31.1


-- 
Mailing list info: https://lists.linux.it/listinfo/ltp

[LTP] [PATCH 1/3] Hugetlb: Migrating libhugetlbfs brk_near_huge

[Tarun Sahu]

Migrating the libhugetlbfs/testcases/brk_near_huge.c test

Test Description:
Certain kernels have a bug where brk() does not perform the same
checks that a MAP_FIXED mmap() will, allowing brk() to create a
normal page VMA in a hugepage only address region. This can lead
to oopses or other badness.

Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap07.c  | 156 ++++++++++++++++++
 testcases/kernel/mem/hugetlb/lib/hugetlb.c    |  75 +++++++++
 testcases/kernel/mem/hugetlb/lib/hugetlb.h    |   5 +
 5 files changed, 238 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index f719217ab..f7ff81cb3 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -3,6 +3,7 @@ hugemmap02 hugemmap02
 hugemmap04 hugemmap04
 hugemmap05 hugemmap05
 hugemmap06 hugemmap06
+hugemmap07 hugemmap07
 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 ff2910533..df5256ec8 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -4,6 +4,7 @@
 /hugetlb/hugemmap/hugemmap04
 /hugetlb/hugemmap/hugemmap05
 /hugetlb/hugemmap/hugemmap06
+/hugetlb/hugemmap/hugemmap07
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c
new file mode 100644
index 000000000..bd33d9816
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap07.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright (C) 2005-2006 David Gibson & Adam Litke, IBM Corporation.
+ * Author: David Gibson & Adam Litke
+ */
+
+/*\
+ *
+ * [Description]
+ *
+ * brk() near hugepage:
+ * Certain kernels have a bug where brk() does not perform the same
+ * checks that a MAP_FIXED mmap() will, allowing brk() to create a
+ * normal page VMA in a hugepage only address region. This can lead
+ * to oopses or other badness.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <sys/mount.h>
+#include <limits.h>
+#include <sys/param.h>
+#include <sys/types.h>
+
+#include "hugetlb.h"
+#include "tst_safe_stdio.h"
+
+static int  fd = -1;
+static char hfile[MAXPATHLEN];
+static long hpage_size;
+
+static int arch_has_slice_support(void)
+{
+#ifdef __powerpc64__
+	char mmu_type[16];
+	FILE *fp;
+	int ret;
+
+	fp = SAFE_POPEN("cat /proc/cpuinfo | grep MMU | awk '{ print $3}'", "r");
+	ret = fscanf(fp, "%s", mmu_type);
+	pclose(fp);
+
+	if (ret < 0)
+		tst_brk(TBROK, "Failed to determine MMU type");
+
+	return strcmp(mmu_type, "Hash") == 0;
+#elif defined(__powerpc__) && !defined(PPC_NO_SEGMENTS)
+	return 1;
+#else
+	return 0;
+#endif
+}
+
+#ifdef __powerpc64__
+static void *next_chunk(void *addr)
+{
+	if (!arch_has_slice_support())
+		return PALIGN(addr, SAFE_READ_MEMINFO("Hugepagesize:")*1024);
+
+	if ((unsigned long)addr < 0x100000000UL)
+		/* 256M segments below 4G */
+		return PALIGN(addr, 0x10000000UL);
+	/* 1TB segments above */
+	return PALIGN(addr, 0x10000000000UL);
+}
+#elif defined(__powerpc__) && !defined(PPC_NO_SEGMENTS)
+static void *next_chunk(void *addr)
+{
+	return PALIGN(addr, 0x10000000UL);
+}
+#elif defined(__ia64__)
+static void *next_chunk(void *addr)
+{
+	return PALIGN(addr, 0x8000000000000000UL);
+}
+#else
+static void *next_chunk(void *addr)
+{
+	return PALIGN(addr, SAFE_READ_MEMINFO("Hugepagesize:")*1024);
+}
+#endif
+
+static void run_test(void)
+{
+	void *brk0, *hugemap_addr, *newbrk;
+	char *p;
+	int err;
+
+	brk0 = sbrk(0);
+	tst_res(TINFO, "Initial break at %p", brk0);
+
+	hugemap_addr = next_chunk(brk0) + hpage_size;
+
+	p = SAFE_MMAP(hugemap_addr, hpage_size, PROT_READ|PROT_WRITE,
+			MAP_PRIVATE|MAP_FIXED, fd, 0);
+	if (p != hugemap_addr) {
+		tst_res(TFAIL, "mmap() at unexpected address %p instead of %p\n", p,
+		     hugemap_addr);
+		goto cleanup;
+	}
+
+	newbrk = next_chunk(brk0) + getpagesize();
+	err = brk((void *)newbrk);
+	if (err == -1) {
+		/* Failing the brk() is an acceptable kernel response */
+		tst_res(TPASS, "Failing the brk is an acceptable response");
+	} else {
+		/* Suceeding the brk() is acceptable iff the new memory is
+		 * properly accesible and we don't have a kernel blow up when
+		 * we touch it.
+		 */
+		tst_res(TINFO, "New break at %p", newbrk);
+		memset(brk0, 0, newbrk-brk0);
+		tst_res(TPASS, "memory is accessible, hence successful brk() is "
+				"an acceptable response");
+	}
+cleanup:
+	SAFE_MUNMAP(p, hpage_size);
+	err = brk(brk0);
+	if (err == -1)
+		tst_brk(TBROK, "Failed to set break at the original position");
+}
+
+static void setup(void)
+{
+	if (!Hopt)
+		Hopt = tst_get_tmpdir();
+	SAFE_MOUNT("none", Hopt, "hugetlbfs", 0, NULL);
+
+	snprintf(hfile, sizeof(hfile), "%s/ltp_hugetlbfile%d", Hopt, getpid());
+	hpage_size = SAFE_READ_MEMINFO("Hugepagesize:")*1024;
+
+	fd = SAFE_OPEN(hfile, O_RDWR | O_CREAT, 0600);
+	SAFE_UNLINK(hfile);
+}
+
+static void cleanup(void)
+{
+	if (fd >= 0)
+		SAFE_CLOSE(fd);
+	SAFE_UMOUNT(Hopt);
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.needs_tmpdir = 1,
+	.options = (struct tst_option[]) {
+		{"H:", &Hopt,   "Location of hugetlbfs, i.e.  -H /var/hugetlbfs"},
+		{"s:", &nr_opt, "Set the number of the been allocated hugepages"},
+		{}
+	},
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+	.hugepages = {1, TST_NEEDS},
+};
diff --git a/testcases/kernel/mem/hugetlb/lib/hugetlb.c b/testcases/kernel/mem/hugetlb/lib/hugetlb.c
index 1204f21d2..d215c69dd 100644
--- a/testcases/kernel/mem/hugetlb/lib/hugetlb.c
+++ b/testcases/kernel/mem/hugetlb/lib/hugetlb.c
@@ -29,15 +29,19 @@
  *	getipckey()
  *	getuserid()
  *	rm_shm()
+ *	read_maps()
+ *	test_addr_huge()
  */
 
 #define TST_NO_DEFAULT_MAIN
+#define _GNU_SOURCE
 #include <sys/types.h>
 #include <sys/ipc.h>
 #include <sys/shm.h>
 #include <sys/time.h>
 #include <pwd.h>
 #include "hugetlb.h"
+#include "tst_safe_stdio.h"
 
 key_t shmkey;
 
@@ -111,3 +115,74 @@ void rm_shm(int shm_id)
 		tst_res(TINFO, "id = %d", shm_id);
 	}
 }
+
+#define MAPS_BUF_SZ 4096
+#define HUGETLBFS_MAGIC 0x958458f6
+
+int read_maps(unsigned long addr, char *buf)
+{
+	FILE *f;
+	char line[MAPS_BUF_SZ];
+	char *tmp;
+
+	f = SAFE_FOPEN("/proc/self/maps", "r");
+
+	while (1) {
+		unsigned long start, end, off, ino;
+		int ret;
+
+		tmp = fgets(line, MAPS_BUF_SZ, f);
+		if (!tmp)
+			break;
+
+		buf[0] = '\0';
+		ret = sscanf(line, "%lx-%lx %*s %lx %*s %ld %255s",
+			     &start, &end, &off, &ino,
+			     buf);
+		if ((ret < 4) || (ret > 5)) {
+			tst_res(TWARN, "Couldn't parse /proc/self/maps line: %s\n",
+			      line);
+			SAFE_FCLOSE(f);
+			return -1;
+		}
+
+		if ((start <= addr) && (addr < end)) {
+			SAFE_FCLOSE(f);
+			return 1;
+		}
+	}
+
+	SAFE_FCLOSE(f);
+	return 0;
+}
+
+int test_addr_huge(void *p)
+{
+	char name[256];
+	char *dirend;
+	int ret;
+	struct statfs64 sb;
+
+	ret = read_maps((unsigned long)p, name);
+	if (ret < 0)
+		return ret;
+	if (ret == 0) {
+		tst_res(TWARN, "Couldn't find address %p in /proc/self/maps\n", p);
+		return -1;
+	}
+
+	/* looks like a filename? */
+	if (name[0] != '/')
+		return 0;
+
+	/* Truncate the filename portion */
+	dirend = strrchr(name, '/');
+	if (dirend && dirend > name)
+		*dirend = '\0';
+
+	ret = statfs64(name, &sb);
+	if (ret)
+		return -1;
+
+	return (sb.f_type == HUGETLBFS_MAGIC);
+}
diff --git a/testcases/kernel/mem/hugetlb/lib/hugetlb.h b/testcases/kernel/mem/hugetlb/lib/hugetlb.h
index f75109f3e..c522314eb 100644
--- a/testcases/kernel/mem/hugetlb/lib/hugetlb.h
+++ b/testcases/kernel/mem/hugetlb/lib/hugetlb.h
@@ -20,6 +20,9 @@
 #include "old_tmpdir.h"
 #include "mem.h"
 
+#define ALIGN(x, a)	(((x) + (a) - 1) & ~((a) - 1))
+#define PALIGN(p, a) ((void *)ALIGN((unsigned long)(p), (a)))
+
 #define SHM_RD	0400
 #define SHM_WR	0200
 #define SHM_RW	(SHM_RD|SHM_WR)
@@ -39,5 +42,7 @@ extern key_t shmkey;			/* an IPC key generated by ftok() */
 int getipckey(void);
 int getuserid(char *user);
 void rm_shm(int shm_id);
+int test_addr_huge(void *p);
+int read_maps(unsigned long addr, char *buf);
 
 #endif /* hugetlb.h */
-- 
2.31.1


-- 
Mailing list info: https://lists.linux.it/listinfo/ltp

[LTP] [PATCH 2/3] Hugetlb: Migrating libhugetlbfs chunk-overcommit

[Tarun Sahu]

Migrating the libhugetlbfs/testcases/chunk-overcommit.c test

Test Description: Some kernel versions after hugepage demand allocation was
added used a dubious heuristic to check if there was enough hugepage space
available for a given mapping.  The number of not-already-instantiated
pages in the mapping was compared against the total hugepage free pool. It
was very easy to confuse this heuristic into overcommitting by allocating
hugepage memory in chunks, each less than the total available pool size but
together more than available.  This would generally lead to OOM SIGKILLs of
one process or another when it tried to instantiate pages beyond the
available pool.

Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap08.c  | 166 ++++++++++++++++++
 3 files changed, 168 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap08.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index f7ff81cb3..664f18827 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -4,6 +4,7 @@ hugemmap04 hugemmap04
 hugemmap05 hugemmap05
 hugemmap06 hugemmap06
 hugemmap07 hugemmap07
+hugemmap08 hugemmap08
 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 df5256ec8..003ce422b 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -5,6 +5,7 @@
 /hugetlb/hugemmap/hugemmap05
 /hugetlb/hugemmap/hugemmap06
 /hugetlb/hugemmap/hugemmap07
+/hugetlb/hugemmap/hugemmap08
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap08.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap08.c
new file mode 100644
index 000000000..2fbda0fcb
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap08.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright (C) 2005-2006 David Gibson & Adam Litke, IBM Corporation.
+ * Author: David Gibson & Adam Litke
+ */
+
+/*\
+ * [Description]
+ *
+ * Chunk Overcommit:
+ * Some kernel versions after hugepage demand allocation was added used a
+ * dubious heuristic to check if there was enough hugepage space available
+ * for a given mapping.  The number of not-already-instantiated pages in
+ * the mapping was compared against the total hugepage free pool. It was
+ * very easy to confuse this heuristic into overcommitting by allocating
+ * hugepage memory in chunks, each less than the total available pool size
+ * but together more than available.  This would generally lead to OOM
+ * SIGKILLs of one process or another when it tried to instantiate pages
+ * beyond the available pool.
+ *
+ * HISTORY
+ *
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mount.h>
+#include <limits.h>
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <signal.h>
+
+#include "hugetlb.h"
+
+#define PROC_OVERCOMMIT "/proc/sys/vm/nr_overcommit_hugepages"
+#define WITH_OVERCOMMIT 0
+#define WITHOUT_OVERCOMMIT 1
+
+static char hfile[MAXPATHLEN];
+static int fd = -1;
+static long hpage_size;
+
+static void test_chunk_overcommit(void)
+{
+	unsigned long totpages, chunk1, chunk2;
+	void *p, *q;
+	pid_t child;
+	int status;
+
+	fd = SAFE_OPEN(hfile, O_RDWR | O_CREAT, 0600);
+	SAFE_UNLINK(hfile);
+
+	totpages = SAFE_READ_MEMINFO("HugePages_Free:");
+
+	chunk1 = (totpages / 2) + 1;
+	chunk2 = totpages - chunk1 + 1;
+
+	tst_res(TINFO, "Free: %ld hugepages available: "
+	       "chunk1=%ld chunk2=%ld", totpages, chunk1, chunk2);
+
+	p = SAFE_MMAP(NULL, chunk1*hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+		 fd, 0);
+
+	q = mmap(NULL, chunk2*hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+		 fd, chunk1*hpage_size);
+	if (q == MAP_FAILED) {
+		if (errno != ENOMEM) {
+			tst_res(TFAIL | TERRNO, "mmap() chunk2");
+			goto cleanup1;
+		} else {
+			tst_res(TPASS, "Successful without overcommit pages");
+			goto cleanup1;
+		}
+	}
+
+	tst_res(TINFO, "Looks like we've overcommitted, testing...");
+	/* Looks like we're overcommited, but we need to confirm that
+	 * this is bad.  We touch it all in a child process because an
+	 * overcommit will generally lead to a SIGKILL which we can't
+	 * handle, of course.
+	 */
+	child = SAFE_FORK();
+
+	if (child == 0) {
+		memset(p, 0, chunk1*hpage_size);
+		memset(q, 0, chunk2*hpage_size);
+		exit(0);
+	}
+
+	SAFE_WAITPID(child, &status, 0);
+
+	if (WIFSIGNALED(status)) {
+		tst_res(TFAIL, "Killed by signal '%s' due to overcommit",
+		     tst_strsig(WTERMSIG(status)));
+		goto cleanup2;
+	}
+
+	tst_res(TPASS, "Successful with overcommit pages");
+
+cleanup2:
+	SAFE_MUNMAP(q, chunk2*hpage_size);
+
+cleanup1:
+	SAFE_MUNMAP(p, chunk1*hpage_size);
+	SAFE_CLOSE(fd);
+}
+
+static void run_test(unsigned int test_type)
+{
+	unsigned long saved_oc_hugepages;
+
+	SAFE_FILE_SCANF(PROC_OVERCOMMIT, "%ld", &saved_oc_hugepages);
+	switch (test_type) {
+	case WITHOUT_OVERCOMMIT:
+		tst_res(TINFO, "Without overcommit testing...");
+		if (saved_oc_hugepages > 0)
+			SAFE_FILE_PRINTF(PROC_OVERCOMMIT, "%d", 0);
+		break;
+	case WITH_OVERCOMMIT:
+		tst_res(TINFO, "With overcommit testing...");
+		if (saved_oc_hugepages == 0)
+			SAFE_FILE_PRINTF(PROC_OVERCOMMIT, "%d", 2);
+		break;
+	}
+	test_chunk_overcommit();
+}
+
+static void setup(void)
+{
+	if (!Hopt)
+		Hopt = tst_get_tmpdir();
+	SAFE_MOUNT("none", Hopt, "hugetlbfs", 0, NULL);
+
+	snprintf(hfile, sizeof(hfile), "%s/ltp_huetlbfile%d", Hopt, getpid());
+	hpage_size = SAFE_READ_MEMINFO("Hugepagesize:")*1024;
+}
+
+static void cleanup(void)
+{
+	if (fd >= 0)
+		SAFE_CLOSE(fd);
+	SAFE_UMOUNT(Hopt);
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.needs_tmpdir = 1,
+	.forks_child = 1,
+	.options = (struct tst_option[]) {
+		{"H:", &Hopt,   "Location of hugetlbfs, i.e.  -H /var/hugetlbfs"},
+		{"s:", &nr_opt, "Set the number of the been allocated hugepages"},
+		{}
+	},
+	.save_restore = (const struct tst_path_val[]) {
+		{PROC_OVERCOMMIT, NULL},
+		{}
+	},
+	.tcnt = 2,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test = run_test,
+	.hugepages = {3, TST_NEEDS},
+};
+
-- 
2.31.1


-- 
Mailing list info: https://lists.linux.it/listinfo/ltp

[LTP] [PATCH 3/3] Hugetlb: Migrating libhugetlbfs corrupt-by-cow-opt

[Tarun Sahu]

Migrating the libhugetlbfs/testcases/corrupt-by-cow-opt.c test

Test Description: Test sanity of cow optimization on page cache. If a page
in page cache has only 1 ref count, it is mapped for a private mapping
directly and is overwritten freely, so next time we access the page, we
can see corrupt data.

Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
---
 runtest/hugetlb                               |  1 +
 testcases/kernel/mem/.gitignore               |  1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap09.c  | 90 +++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap09.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 664f18827..e2ada7a97 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -5,6 +5,7 @@ hugemmap05 hugemmap05
 hugemmap06 hugemmap06
 hugemmap07 hugemmap07
 hugemmap08 hugemmap08
+hugemmap09 hugemmap09
 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 003ce422b..1a242ffe0 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -6,6 +6,7 @@
 /hugetlb/hugemmap/hugemmap06
 /hugetlb/hugemmap/hugemmap07
 /hugetlb/hugemmap/hugemmap08
+/hugetlb/hugemmap/hugemmap09
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap09.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap09.c
new file mode 100644
index 000000000..067556793
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap09.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright (C) 2013 Joonsoo Kim, LG Electronics.
+ * Author: Joonsoo Kim
+ */
+
+/*\
+ * [Description]
+ *
+ * Corrupt by COW optimization:
+ * Test sanity of cow optimization on page cache. If a page in page cache
+ * has only 1 ref count, it is mapped for a private mapping directly and
+ * is overwritten freely, so next time we access the page, we can see
+ * corrupt data.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <sys/mount.h>
+#include <limits.h>
+#include <sys/param.h>
+#include <sys/types.h>
+
+#include "hugetlb.h"
+
+static int  fd = -1;
+static char hfile[MAXPATHLEN];
+static long hpage_size;
+
+static void run_test(void)
+{
+	char *p;
+	char c;
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+	*p = 's';
+	tst_res(TINFO, "Write %c to %p via shared mapping", *p, p);
+	SAFE_MUNMAP(p, hpage_size);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+	*p = 'p';
+	tst_res(TINFO, "Write %c to %p via private mapping", *p, p);
+	SAFE_MUNMAP(p, hpage_size);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+	c = *p;
+	tst_res(TINFO, "Read %c from %p via shared mapping", *p, p);
+	SAFE_MUNMAP(p, hpage_size);
+
+	/* Direct write from huge page */
+	if (c != 's')
+		tst_res(TFAIL, "Data got corrupted.");
+	else
+		tst_res(TPASS, "Successful");
+}
+
+static void setup(void)
+{
+	if (!Hopt)
+		Hopt = tst_get_tmpdir();
+	SAFE_MOUNT("none", Hopt, "hugetlbfs", 0, NULL);
+
+	snprintf(hfile, sizeof(hfile), "%s/ltp_hugetlbfile%d", Hopt, getpid());
+	hpage_size = SAFE_READ_MEMINFO("Hugepagesize:")*1024;
+
+	fd = SAFE_OPEN(hfile, O_RDWR | O_CREAT, 0600);
+	SAFE_UNLINK(hfile);
+}
+
+static void cleanup(void)
+{
+	if (fd >= 0)
+		SAFE_CLOSE(fd);
+	SAFE_UMOUNT(Hopt);
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.needs_tmpdir = 1,
+	.options = (struct tst_option[]) {
+		{"H:", &Hopt,   "Location of hugetlbfs, i.e.  -H /var/hugetlbfs"},
+		{"s:", &nr_opt, "Set the number of the been allocated hugepages"},
+		{}
+	},
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+	.hugepages = {2, TST_NEEDS},
+};
-- 
2.31.1


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