hugetlb/hugemmap: add new testcase hugemmap06.c

From: "Li Wang" <[email protected]>
To: [email protected]
Sent: Thursday, 19 November, 2015 10:34:35 AM
Subject: [LTP] [PATCH] hugetlb/hugemmap: add new testcase hugemmap06.c

Description of Problem:

	There is a race condition if we map a same file on different processes.
	Region tracking is protected by mmap_sem and hugetlb_instantiation_mutex.
	When we do mmap, we don't grab a hugetlb_instantiation_mutex, but only
	mmap_sem (exclusively).  This doesn't prevent other tasks from modifying
	the region structure, so it can be modified by two processes concurrently.

	Testcase hugemmap06.c is the trigger to cause system crash:

        crash> bt -s
        PID: 4492   TASK: ffff88033e437520  CPU: 2   COMMAND: "hugemmap06"
         #0 [ffff88033dbb3960] machine_kexec+395 at ffffffff8103d1ab
         #1 [ffff88033dbb39c0] crash_kexec+114 at ffffffff810cc4f2
         #2 [ffff88033dbb3a90] oops_end+192 at ffffffff8153c840
         #3 [ffff88033dbb3ac0] die+91 at ffffffff81010f5b
         #4 [ffff88033dbb3af0] do_general_protection+338 at ffffffff8153c332
         #5 [ffff88033dbb3b20] general_protection+37 at ffffffff8153bb05
            [exception RIP: list_del+40]
            RIP: ffffffff812a3598  RSP: ffff88033dbb3bd8  RFLAGS: 00010292
            RAX: dead000000100100  RBX: ffff88013cf37340  RCX:
            0000000000002dc2
            RDX: dead000000200200  RSI: 0000000000000046  RDI:
            0000000000000009
            RBP: ffff88033dbb3be8   R8: 0000000000015598   R9:
            0000000000000000
            R10: 000000000000000f  R11: 0000000000000009  R12:
            000000000000000a
            R13: ffff88033d64b9e8  R14: ffff88033e5b9720  R15:
            ffff88013cf37340
            ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0000
         #6 [ffff88033dbb3bf0] region_add+154 at ffffffff811698da
         #7 [ffff88033dbb3c40] alloc_huge_page+669 at ffffffff8116a61d
         #8 [ffff88033dbb3ce0] hugetlb_fault+1083 at ffffffff8116b9bb
         #9 [ffff88033dbb3d90] handle_mm_fault+917 at ffffffff81153295
        #10 [ffff88033dbb3e00] __do_page_fault+326 at ffffffff8104f156
        #11 [ffff88033dbb3f20] do_page_fault+62 at ffffffff8153e78e
        #12 [ffff88033dbb3f50] page_fault+37 at ffffffff8153bb35
            RIP: 00000000004027c6  RSP: 00007f7cadef9e80  RFLAGS: 00010297
            RAX: 000000005a49238f  RBX: 00007ffcb2d19320  RCX:
            000000357498e084
            RDX: 000000357498e0b0  RSI: 00007f7cadef9e5c  RDI:
            000000357498e4e0
            RBP: 0000000000000008   R8: 000000357498e0a0   R9:
            000000357498e100
            R10: 00007f7cadefa9d0  R11: 0000000000000206  R12:
            0000000000000007
            R13: 0000000000000002  R14: 0000000000000003  R15:
            00002aaaac000000
            ORIG_RAX: ffffffffffffffff  CS: 0033  SS: 002b

The fix are all these below commits:

	commit f522c3ac00a49128115f99a5fcb95a447601c1c3
	Author:Joonsoo Kim < iamjoonsoo.kim @ lge.com >
	Date:Wed Sep 11 14:21:53 2013 - 0700

	commit 9119 a41e9091fb3a8204039d595bcdae24193c57
	Author:Joonsoo Kim < iamjoonsoo.kim @ lge.com >
	Date:Thu Apr 3 14:47:25 2014 - 0700

	commit 7 b24d8616be33616efd41ff67d3c76362c60ca84
	Author:Davidlohr Bueso < davidlohr @ hp.com >
	Date:Thu Apr 3 14:47:27 2014 - 0700

	commit 1406ec9 ba6c65cb69e9243bff07ca3f51e2525e0
	Author:Joonsoo Kim < iamjoonsoo.kim @ lge.com >
	Date:Thu Apr 3 14:47:26 2014 - 0700

Signed-off-by Li Wang <[email protected]>

---
 runtest/hugetlb                                    |   1 +
 testcases/kernel/mem/.gitignore                    |   1 +
 testcases/kernel/mem/hugetlb/hugemmap/Makefile     |   2 +
 testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c | 190
 +++++++++++++++++++++
 4 files changed, 194 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c

runtest/hugetlb +1 -0

index 2e9f215..ac24513 100644
@@ -2,6 +2,7 @@ hugemmap01 hugemmap01
 hugemmap02 hugemmap02
 hugemmap04 hugemmap04
 hugemmap05 hugemmap05
+hugemmap06 hugemmap06
 hugemmap05_1 hugemmap05 -m
 hugemmap05_2 hugemmap05 -s
 hugemmap05_3 hugemmap05 -s -m

testcases/kernel/mem/.gitignore +1 -0

index 4702377..ac8e6d8 100644
@@ -3,6 +3,7 @@
 /hugetlb/hugemmap/hugemmap02
 /hugetlb/hugemmap/hugemmap04
 /hugetlb/hugemmap/hugemmap05
+/hugetlb/hugemmap/hugemmap06
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03

testcases/kernel/mem/hugetlb/hugemmap/Makefile +2 -0

index 71da630..3d22042 100644
@@ -25,3 +25,5 @@ top_srcdir		?= ../../../../..
 include $(top_srcdir)/include/mk/testcases.mk
 include $(top_srcdir)/testcases/kernel/mem/include/libmem.mk
 include $(top_srcdir)/include/mk/generic_leaf_target.mk
+
+hugemmap06: CFLAGS+=-pthread

testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c new file +24 -0

new file mode 100644
index 0000000..f22aed2
@@ -0,0 +1,190 @@
+/*
+ *  Copyright (c) Author: Herton R. Krzesinski <[email protected]>
+ *                Modify: Li Wang <[email protected]>
+ *
+ *  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 2 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, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ *  02110-1301 USA
+ */
+
+/*
+ *  DESCRIPTION
+ *
+ *    There is a race condition if we map a same file on different

processes.
+ * Region tracking is protected by mmap_sem and
hugetlb_instantiation_mutex.
+ * When we do mmap, we don't grab a hugetlb_instantiation_mutex, but only
+ * mmap_sem (exclusively). This doesn't prevent other tasks from
modifying
+ * the region structure, so it can be modified by two processes
concurrently.
+ *
+ * This bug was fixed on stable kernel by commits:
+ *

+ *        commit f522c3ac00a49128115f99a5fcb95a447601c1c3
+ *        Author: Joonsoo Kim <[email protected]>
+ *        Date:   Wed Sep 11 14:21:53 2013 -0700
+ *
+ *        commit 9119a41e9091fb3a8204039d595bcdae24193c57
+ *        Author: Joonsoo Kim <[email protected]>
+ *        Date:   Thu Apr 3 14:47:25 2014 -0700
+ *
+ *        commit 7b24d8616be33616efd41ff67d3c76362c60ca84
+ *        Author: Davidlohr Bueso <[email protected]>
+ *        Date:   Thu Apr 3 14:47:27 2014 -0700
+ *
+ *        commit 1406ec9ba6c65cb69e9243bff07ca3f51e2525e0
+ *        Author: Joonsoo Kim <[email protected]>
+ *        Date:   Thu Apr 3 14:47:26 2014 -0700

+ */

testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c new file +16 -0

+#include <unistd.h>
+
+#include "test.h"
+#include "mem.h"
+
+char *TCID = "hugemmap06";
+int TST_TOTAL = 5;
+
+static long hpage_size;
+static long hugepages;
+static long orig_hugepages;
+
+struct mp {
+	void *addr;
+	int sz;
+};

testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c new file +31 -0

+
+	hugepages = orig_hugepages + ARSZ + 1;
+	set_sys_tune("nr_hugepages", hugepages, 1);
+
+	TEST_PAUSE;
+}
+
+void cleanup(void)
+{
+	set_sys_tune("nr_hugepages", orig_hugepages, 0);
+}
+
+void *thr(void *arg)
+{
+	struct mp *mmap_sz = arg;
+	int i, lim, a, b, c;
+
+	srand(time(NULL));
+	lim = rand() % 10;
+	for (i = 0; i < lim; i++) {
+		a = rand() % mmap_sz->sz;
+		for (c = 0; c <= a; c++) {
+			b = rand() % mmap_sz->sz;
+			*((int *)((char *)mmap_sz->addr + (b * hpage_size))) = rand();
+		}
+	}
+	return NULL;
+}
+
+void do_mmap(void)
+{

testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c new file +66 -1

+
+	if (addr == MAP_FAILED) {
+		if (errno == ENOMEM) {
+			tst_brkm(TCONF, cleanup,
+				"Cannot allocate hugepage, memory too fragmented?");
+		}
+
+		tst_brkm(TBROK | TERRNO, cleanup, "Cannot allocate hugepage");
+	}
+
+	for (i = 0; i < ARSZ; i++) {
+		mmap_sz[i].sz = sz;
+		mmap_sz[i].addr = addr;
+
+		TEST(pthread_create(tid + i, NULL, thr, &mmap_sz[i]));
+		if (TEST_RETURN)
+			tst_brkm(TBROK | TRERRNO, cleanup,
+					"pthread_create failed");
+
+		new_addr = mmap(addr, (sz + 1) * hpage_size,
+				PROT_READ | PROT_WRITE,
+				MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED,
+				-1, 0);
+
+		if (new_addr == MAP_FAILED) {
+			TEST(pthread_join(tid[i], NULL));
+			if (TEST_RETURN)
+				tst_brkm(TBROK | TRERRNO, cleanup,
+						"pthread_join failed");
+			tst_brkm(TFAIL | TERRNO, cleanup, "mremap failed");
+		}
+		sz++;
+		addr = new_addr;
+	}
+
+	for (--i; i >= 0; i--) {
+		TEST(pthread_join(tid[i], NULL));
+		if (TEST_RETURN)
+			tst_brkm(TBROK | TRERRNO, cleanup,
+					"pthread_join failed");
+	}
+
+	if (munmap(addr, sz * hpage_size) == -1)
+		tst_brkm(TFAIL | TERRNO, cleanup, "huge munmap failed");
+}
+
+int main(int ac, char **av)
+{
+	int lc, i;
+
+	tst_parse_opts(ac, av, NULL, NULL);
+
+	setup();
+
+	for (lc = 0; TEST_LOOPING(lc); lc++) {
+		tst_count = 0;
+
+		for (i = 0; i < TST_TOTAL; i++)
+			do_mmap();
+
+		tst_resm(TPASS, "No regression found.");
+	}
+
+	cleanup();
+	tst_exit();
+}
--

1.8.3.1

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

----- Original Message -----

Quoted 5 lines

From: "Li Wang" <[email protected]>
To: [email protected]
Sent: Thursday, 19 November, 2015 10:34:35 AM
Subject: [LTP] [PATCH] hugetlb/hugemmap: add new testcase hugemmap06.c

Quoted 1 line

+#include <time.h>

Hi,

wait.h and time.h appear to be unnecessary

testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c line 83

Quoted 11 lines

testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c new file +11 -0

+};
+
+#define ARSZ 125
+
+void setup(void)
+{
+     tst_require_root();
+
+     hpage_size = read_meminfo("Hugepagesize:") * 1024;
+
+     orig_hugepages = get_sys_tune("nr_hugepages");

Do we care about huge pages availability here? Or do we expect, that user running hugetlb runtest file is resposible for checking that?

It's easy to imagine, that some kernels/systems won't support huge pages or they may not have enough of them. (For example with 16M pages this requires over 2GB)

testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c line 124

Quoted 5 lines

testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c new file +4 -0

+     addr = mmap(NULL, sz * hpage_size,
+                     PROT_READ | PROT_WRITE,
+                     MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
+                     -1, 0);

How about allocating the largest area first and then mmaping smaller ones on top of it?

That could prevent situation where first smallest area mmaps a gap between existing libraries/heap/etc. and then larger ones with same start overlap with those - since we write to those areas, bad things could happen.

Regards,
Jan