[LTP] [PATCH V3] madvice: new case for madvise(WILLNEED)

* [LTP] [PATCH V3] madvice: new case for madvise(WILLNEED)
@ 2016-04-01  5:24 Li Wang
  2016-04-01  5:30 ` Li Wang
  2016-04-04 17:30 ` Cyril Hrubis
  0 siblings, 2 replies; 4+ messages in thread
From: Li Wang @ 2016-04-01  5:24 UTC (permalink / raw)
  To: ltp

Page fault occurs in spite that madvise(WILLNEED) system call is called
to prefetch the page. This issue is reproduced by running a program
which sequentially accesses to a shared memory and calls madvise(WILLNEED)
to the next page on a page fault.

Fixed by commit:
	55231e5c898 mm: madvise: fix MADV_WILLNEED on shmem swapouts

Signed-off-by: Li Wang <liwang@redhat.com>
---
 runtest/syscalls                              |   1 +
 testcases/kernel/syscalls/.gitignore          |   1 +
 testcases/kernel/syscalls/madvise/madvise06.c | 157 ++++++++++++++++++++++++++
 3 files changed, 159 insertions(+)
 create mode 100644 testcases/kernel/syscalls/madvise/madvise06.c

diff --git a/runtest/syscalls b/runtest/syscalls
index b41c927..732c2ca 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -743,6 +743,7 @@ madvise02 madvise02
 madvise03 madvise03
 madvise04 madvise04
 madvise05 madvise05
+madvise06 madvise06
 
 newuname01 newuname01
 
diff --git a/testcases/kernel/syscalls/.gitignore b/testcases/kernel/syscalls/.gitignore
index 0540928..ffa5db1 100644
--- a/testcases/kernel/syscalls/.gitignore
+++ b/testcases/kernel/syscalls/.gitignore
@@ -504,6 +504,7 @@
 /madvise/madvise03
 /madvise/madvise04
 /madvise/madvise05
+/madvise/madvise06
 /mallopt/mallopt01
 /mbind/mbind01
 /memcmp/memcmp01
diff --git a/testcases/kernel/syscalls/madvise/madvise06.c b/testcases/kernel/syscalls/madvise/madvise06.c
new file mode 100644
index 0000000..44a40ba
--- /dev/null
+++ b/testcases/kernel/syscalls/madvise/madvise06.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2016 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
+ *
+ *   Page fault occurs in spite that madvise(WILLNEED) system call is called
+ *   to prefetch the page. This issue is reproduced by running a program
+ *   which sequentially accesses to a shared memory and calls madvise(WILLNEED)
+ *   to the next page on a page fault.
+ *
+ *   This bug is present in all RHEL7 versions. It looks like this was fixed in
+ *   mainline kernel > v3.15 by the following patch:
+ *
+ *   commit 55231e5c898c5c03c14194001e349f40f59bd300
+ *   Author: Johannes Weiner <hannes@cmpxchg.org>
+ *   Date:   Thu May 22 11:54:17 2014 -0700
+ *
+ *       mm: madvise: fix MADV_WILLNEED on shmem swapouts
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <sys/sysinfo.h>
+
+#include "test.h"
+#include "safe_macros.h"
+
+char *TCID = "madvise06";
+int TST_TOTAL = 1;
+
+#ifdef __x86_64__
+
+#define GB_SZ  (1024*1024*1024)
+#define PG_SZ  (4*1024)
+
+static long dst_max;
+
+static void setup(void);
+static int  get_page_fault_num(void);
+static void test_advice_willneed(void);
+
+int main(int argc, char *argv[])
+{
+	int lc;
+
+	tst_parse_opts(argc, argv, NULL, NULL);
+
+	setup();
+
+	for (lc = 0; TEST_LOOPING(lc); lc++)
+		test_advice_willneed();
+
+	tst_exit();
+}
+
+static void setup(void)
+{
+	struct sysinfo sys_buf;
+
+	sysinfo(&sys_buf);
+
+	if (sys_buf.totalram < 2L * GB_SZ)
+		tst_brkm(TCONF, NULL, "Test requires more than 2GB of RAM");
+	if (sys_buf.totalram > 100L * GB_SZ)
+		tst_brkm(TCONF, NULL, "System RAM is too large, skip test");
+
+	dst_max = sys_buf.totalram / GB_SZ;
+	tst_resm(TINFO, "dst_max = %ld", dst_max);
+
+	tst_sig(NOFORK, DEF_HANDLER, NULL);
+
+	TEST_PAUSE;
+}
+
+static int get_page_fault_num(void)
+{
+	int pg;
+
+	SAFE_FILE_SCANF(NULL, "/proc/self/stat",
+			"%*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %d",
+			&pg);
+
+	return pg;
+}
+
+static void test_advice_willneed(void)
+{
+	int i;
+	char *src;
+	char *dst[100];
+	int page_fault_num_1;
+	int page_fault_num_2;
+
+	/* allocate source memory (1GB only) */
+	src = SAFE_MMAP(NULL, NULL, 1 * GB_SZ, PROT_READ | PROT_WRITE,
+			MAP_SHARED | MAP_ANONYMOUS,
+			-1, 0);
+
+	/* allocate destination memory (array) */
+	for (i = 0; i < dst_max; ++i)
+		dst[i] = SAFE_MMAP(NULL, NULL, 1 * GB_SZ,
+				PROT_READ | PROT_WRITE,
+				MAP_SHARED | MAP_ANONYMOUS,
+				-1, 0);
+
+	/* memmove source to each destination memories (for SWAP-OUT) */
+	for (i = 0; i < dst_max; ++i)
+		memmove(dst[i], src, 1 * GB_SZ);
+
+	tst_resm(TINFO, "PageFault(no madvice): %d", get_page_fault_num());
+
+	/* Do madvice() to dst[0] */
+	TEST(madvise(dst[0], PG_SZ, MADV_WILLNEED));
+	if (TEST_RETURN == -1)
+		tst_brkm(TBROK | TERRNO, NULL, "madvise failed");
+
+	page_fault_num_1 = get_page_fault_num();
+	tst_resm(TINFO, "PageFault(madvice / no mem access): %d",
+			page_fault_num_1);
+
+	*dst[0] = 'a';
+	page_fault_num_2 = get_page_fault_num();
+	tst_resm(TINFO, "PageFault(madvice / mem access): %d",
+			page_fault_num_2);
+
+	if (page_fault_num_1 != page_fault_num_2)
+		tst_resm(TFAIL, "Bug has been reproduced");
+	else
+		tst_resm(TPASS, "Regression test pass");
+
+	SAFE_MUNMAP(NULL, src, 1 * GB_SZ);
+	for (i = 0; i < dst_max; ++i)
+		SAFE_MUNMAP(NULL, dst[i], 1 * GB_SZ);
+}
+
+
+#else
+int main(void)
+{
+	tst_brkm(TCONF, NULL, "Only test on x86_64.");
+}
+#endif
-- 
1.8.3.1


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