[LTP] [PATCH v2 10/13] Hugetlb: Migrating libhugetlbfs readahead_reserve

[Tarun Sahu]

Migrating the libhugetlbfs/testcases/readahead_reserve.c test

Test Description: readahead() on some kernels can cause the reservation
counter to get corrupted. The problem is that the patches are allocated
for the reservation but not faulted in at the time of allocation. The
counters do not get updated and effectively "leak". This test
identifies whether the kernel is vulnerable to the problem or not.
It's fixed in kernel by 'commit f2deae9d4e70
("Remove implementation of readpage from the hugetlbfs_aops")'.

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/hugemmap30.c  | 75 +++++++++++++++++++
 3 files changed, 77 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap30.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 6ec8d1018..60cca4eb7 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -30,6 +30,7 @@ hugemmap26 hugemmap26
 hugemmap27 hugemmap27
 hugemmap28 hugemmap28
 hugemmap29 hugemmap29
+hugemmap30 hugemmap30
 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 fef0a76d6..bb9720452 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -29,6 +29,7 @@
 /hugetlb/hugemmap/hugemmap27
 /hugetlb/hugemmap/hugemmap28
 /hugetlb/hugemmap/hugemmap29
+/hugetlb/hugemmap/hugemmap30
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap30.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap30.c
new file mode 100644
index 000000000..7ed9046f3
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap30.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright (C) 2005-2006 IBM Corporation.
+ * Author: Mel Gorman
+ */
+
+/*\
+ * [Description]
+ *
+ * readahead() on some kernels can cause the reservation counter to get
+ * corrupted. The problem is that the pages are allocated for the
+ * reservation but not faulted in at the time of allocation. The
+ * counters do not get updated and effectively "leak". This test
+ * identifies whether the kernel is vulnerable to the problem or not.
+ * It's fixed in kernel by commit f2deae9d4e70.
+ */
+
+#define _GNU_SOURCE
+#include "hugetlb.h"
+
+#define MNTPOINT "hugetlbfs/"
+static long hpage_size;
+static int fd = -1;
+
+static void run_test(void)
+{
+	void *p;
+	unsigned long initial_rsvd, map_rsvd, readahead_rsvd, end_rsvd;
+
+	fd = tst_creat_unlinked(MNTPOINT, 0);
+	initial_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+		 fd, 0);
+	map_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+	tst_res(TINFO, "map_rsvd: %lu", map_rsvd);
+
+	readahead(fd, 0, hpage_size);
+	readahead_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+	tst_res(TINFO, "readahead_rsvd: %lu", readahead_rsvd);
+
+	memset(p, 1, hpage_size);
+
+	SAFE_MUNMAP(p, hpage_size);
+	SAFE_CLOSE(fd);
+	end_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(end_rsvd, initial_rsvd);
+}
+
+static void setup(void)
+{
+	hpage_size = tst_get_hugepage_size();
+}
+
+static void cleanup(void)
+{
+	if (fd >= 0)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.tags = (struct tst_tag[]) {
+		{"linux-git", "f2deae9d4e70"},
+		{}
+	},
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.needs_hugetlbfs = 1,
+	.needs_tmpdir = 1,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+	.hugepages = {1, TST_NEEDS},
+};
-- 
2.31.1