[LTP] [PATCH v3] hugetlb: add new testcase hugeshmat05.c

[Li Wang]

shmget()/shmat() fails to allocate huge pages shared memory segment
with EINVAL if its size is not in the range [ N*HUGE_PAGE_SIZE - 4095,
N*HUGE_PAGE_SIZE ]. This is a problem in the memory segment size round
up algorithm. The requested size is rounded up to PAGE_SIZE (4096), but
if this roundup does not match HUGE_PAGE_SIZE (2Mb) boundary - the
allocation fails.

This bug is present in all RHEL6 versions, but not in RHEL7. It looks
like this was fixed in mainstream kernel > v3.3 by the following patches:

091d0d5 shm: fix null pointer deref when userspace specifies invalid hugepage size
af73e4d hugetlbfs: fix mmap failure in unaligned size request
42d7395 mm: support more pagesizes for MAP_HUGETLB/SHM_HUGETLB
40716e2 hugetlbfs: fix alignment of huge page requests

Signed-off-by: Li Wang <liwang@redhat.com>
---

Notes:
    v2 --> v3
    - remove the redundant code comments
    - set the test sizes in array tst_sizes[]

 runtest/hugetlb                                    |   1 +
 testcases/kernel/mem/.gitignore                    |   1 +
 .../kernel/mem/hugetlb/hugeshmat/hugeshmat05.c     | 135 +++++++++++++++++++++
 3 files changed, 137 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugeshmat/hugeshmat05.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 2e9f215..75e6426 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -10,6 +10,7 @@ hugeshmat01 hugeshmat01 -i 5
 hugeshmat02 hugeshmat02 -i 5
 hugeshmat03 hugeshmat03 -i 5
 hugeshmat04 hugeshmat04 -i 5
+hugeshmat05 hugeshmat05 -i 5
 
 hugeshmctl01 hugeshmctl01 -i 5
 hugeshmctl02 hugeshmctl02 -i 5
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index 4702377..46c2432 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -7,6 +7,7 @@
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
 /hugetlb/hugeshmat/hugeshmat04
+/hugetlb/hugeshmat/hugeshmat05
 /hugetlb/hugeshmctl/hugeshmctl01
 /hugetlb/hugeshmctl/hugeshmctl02
 /hugetlb/hugeshmctl/hugeshmctl03
diff --git a/testcases/kernel/mem/hugetlb/hugeshmat/hugeshmat05.c b/testcases/kernel/mem/hugetlb/hugeshmat/hugeshmat05.c
new file mode 100644
index 0000000..ead73ca
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugeshmat/hugeshmat05.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * DESCRIPTION
+ *	shmget()/shmat() fails to allocate huge pages shared memory segment
+ *	with EINVAL if its size is not in the range [ N*HUGE_PAGE_SIZE - 4095,
+ *	N*HUGE_PAGE_SIZE ]. This is a problem in the memory segment size round
+ *	up algorithm. The requested size is rounded up to PAGE_SIZE (4096), but
+ *	if this roundup does not match HUGE_PAGE_SIZE (2Mb) boundary - the
+ *	allocation fails.
+ *
+ *	This bug is present in all RHEL6 versions, but not in RHEL7. It looks
+ *	like this was fixed in mainstream kernel > v3.3 by the following patches:
+ *
+ *	091d0d5 (shm: fix null pointer deref when userspace specifies invalid hugepage size)
+ *	af73e4d (hugetlbfs: fix mmap failure in unaligned size request)
+ *	42d7395 (mm: support more pagesizes for MAP_HUGETLB/SHM_HUGETLB)
+ *	40716e2 (hugetlbfs: fix alignment of huge page requests)
+ *
+ * AUTHORS
+ *	Vladislav Dronov <vdronov@redhat.com>
+ *	Li Wang <liwang@redhat.com>
+ *
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+
+#include "test.h"
+#include "mem.h"
+#include "hugetlb.h"
+
+char *TCID = "hugeshmat05";
+int TST_TOTAL = 1;
+
+static long page_size;
+static long hpage_size;
+static long hugepages;
+
+#define N 4
+
+void setup(void)
+{
+	tst_require_root();
+	check_hugepage();
+
+	orig_hugepages = get_sys_tune("nr_hugepages");
+	page_size = getpagesize();
+	hpage_size = read_meminfo("Hugepagesize:") * 1024;
+
+	hugepages = N + 1;
+	set_sys_tune("nr_hugepages", hugepages, 1);
+
+	TEST_PAUSE;
+}
+
+void cleanup(void)
+{
+	set_sys_tune("nr_hugepages", orig_hugepages, 0);
+}
+
+void shm_test(int size)
+{
+	int shmid;
+	char *shmaddr;
+
+	shmid = shmget(IPC_PRIVATE, size, 0600 | IPC_CREAT | SHM_HUGETLB);
+	if (shmid < 0)
+		tst_brkm(TBROK | TERRNO, cleanup, "shmget failed");
+
+	shmaddr = shmat(shmid, 0, 0);
+	if (shmaddr == (char *)-1) {
+		shmctl(shmid, IPC_RMID, NULL);
+		tst_brkm(TFAIL | TERRNO, cleanup, "Bug: shared memory attach failure.");
+	}
+
+	shmaddr[0] = 1;
+	tst_resm(TINFO, "allocated %d huge bytes", size);
+
+	if (shmdt((const void *)shmaddr) != 0) {
+		shmctl(shmid, IPC_RMID, NULL);
+		tst_brkm(TFAIL | TERRNO, cleanup, "Detach failure.");
+	}
+
+	shmctl(shmid, IPC_RMID, NULL);
+}
+
+int main(int ac, char **av)
+{
+	int lc;
+	unsigned int i;
+
+	tst_parse_opts(ac, av, NULL, NULL);
+
+	setup();
+
+	const int tst_sizes[] = {
+		N * hpage_size - page_size,
+		N * hpage_size - page_size -1,
+		hpage_size,
+		hpage_size + 1
+	};
+
+	for (lc = 0; TEST_LOOPING(lc); lc++) {
+		tst_count = 0;
+
+		for(i = 0; i < ARRAY_SIZE(tst_sizes); ++i)
+			shm_test(tst_sizes[i]);
+
+		tst_resm(TPASS, "No regression found.");
+	}
+
+	cleanup();
+	tst_exit();
+}
-- 
1.8.3.1