Use of fadvise() or readahead() on a hugetlbfs-backed memory region can
result in reservations being leaked and in some cases the kernel triggering
a BUG. This patch adds a regression tests for these conditions.
Signed-off-by: Mel Gorman <m...@csn.ul.ie>
---
tests/Makefile | 3 +
tests/fadvise_reserve.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++
tests/readahead_reserve.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++
tests/run_tests.py | 2 +
4 files changed, 174 insertions(+), 1 deletion(-)
diff --git a/tests/Makefile b/tests/Makefile
index d3efe79..7e7dd99 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -8,7 +8,8 @@ LIB_TESTS = gethugepagesize test_root find_path unlinked_fd
misalign \
map_high_truncate_2 truncate_above_4GB direct \
misaligned_offset brk_near_huge task-size-overrun stack_grow_into_huge \
counters quota heap-overflow get_huge_pages get_hugepage_region \
- shmoverride_linked gethugepagesizes madvise_reserve
+ shmoverride_linked gethugepagesizes \
+ madvise_reserve fadvise_reserve readahead_reserve
LIB_TESTS_64 = straddle_4GB huge_at_4GB_normal_below \
huge_below_4GB_normal_above
NOLIB_TESTS = malloc malloc_manysmall dummy heapshrink shmoverride_unlinked
diff --git a/tests/fadvise_reserve.c b/tests/fadvise_reserve.c
new file mode 100644
index 0000000..3ef45f2
--- /dev/null
+++ b/tests/fadvise_reserve.c
@@ -0,0 +1,85 @@
+/*
+ * libhugetlbfs - Easy use of Linux hugepages
+ * Copyright (C) 2005-2006 IBM Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#define _XOPEN_SOURCE 600
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+#include <hugetlbfs.h>
+#include "hugetests.h"
+
+/*
+ * Test rationale:
+ *
+ * fadvise() 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 vunerable to the problem or not.
+ */
+int main(int argc, char *argv[])
+{
+ long hpage_size;
+ int fd;
+ void *p;
+ unsigned long initial_rsvd, map_rsvd, fadvise_rsvd, end_rsvd;
+
+ test_init(argc, argv);
+
+ /* Setup */
+ hpage_size = check_hugepagesize();
+ fd = hugetlbfs_unlinked_fd();
+ if (fd < 0)
+ FAIL("hugetlbfs_unlinked_fd()");
+ initial_rsvd = get_huge_page_counter(hpage_size, HUGEPAGES_RSVD);
+ verbose_printf("Reserve count before map: %lu\n", initial_rsvd);
+
+ /* mmap a region and record reservations */
+ p = mmap(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+ fd, 0);
+ if (p == MAP_FAILED)
+ FAIL("mmap(): %s", strerror(errno));
+ map_rsvd = get_huge_page_counter(hpage_size, HUGEPAGES_RSVD);
+ verbose_printf("Reserve count after map: %lu\n", map_rsvd);
+
+ /* fadvise the region and record reservations */
+ if (posix_fadvise(fd, 0, hpage_size, POSIX_FADV_WILLNEED) == -1)
+ FAIL("fadvise(): %s", strerror(errno));
+ fadvise_rsvd = get_huge_page_counter(hpage_size, HUGEPAGES_RSVD);
+ verbose_printf("Reserve count after fadvise: %lu\n", fadvise_rsvd);
+
+ /* Write the region */
+ memset(p, 1, hpage_size);
+
+ /* Free region */
+ munmap(p, hpage_size);
+ close(fd);
+ end_rsvd = get_huge_page_counter(hpage_size, HUGEPAGES_RSVD);
+ verbose_printf("Reserve count after close(): %lu\n", end_rsvd);
+
+ /* Reserve count should match initial reserve count */
+ if (end_rsvd != initial_rsvd)
+ FAIL("Reserve leaked: %lu != %lu\n", end_rsvd, initial_rsvd);
+
+ PASS();
+}
diff --git a/tests/readahead_reserve.c b/tests/readahead_reserve.c
new file mode 100644
index 0000000..74547a1
--- /dev/null
+++ b/tests/readahead_reserve.c
@@ -0,0 +1,85 @@
+/*
+ * libhugetlbfs - Easy use of Linux hugepages
+ * Copyright (C) 2005-2006 IBM Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+#include <hugetlbfs.h>
+#include "hugetests.h"
+
+/*
+ * Test rationale:
+ *
+ * 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 vunerable to the problem or not.
+ */
+int main(int argc, char *argv[])
+{
+ long hpage_size;
+ int fd;
+ void *p;
+ unsigned long initial_rsvd, map_rsvd, readahead_rsvd, end_rsvd;
+
+ test_init(argc, argv);
+
+ /* Setup */
+ hpage_size = check_hugepagesize();
+ fd = hugetlbfs_unlinked_fd();
+ if (fd < 0)
+ FAIL("hugetlbfs_unlinked_fd()");
+ initial_rsvd = get_huge_page_counter(hpage_size, HUGEPAGES_RSVD);
+ verbose_printf("Reserve count before map: %lu\n", initial_rsvd);
+
+ /* mmap a region and record reservations */
+ p = mmap(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+ fd, 0);
+ if (p == MAP_FAILED)
+ FAIL("mmap(): %s", strerror(errno));
+ map_rsvd = get_huge_page_counter(hpage_size, HUGEPAGES_RSVD);
+ verbose_printf("Reserve count after map: %lu\n", map_rsvd);
+
+ /* readahead the region and record reservations */
+ if (readahead(fd, 0, hpage_size) == -1)
+ FAIL("readahead(): %s", strerror(errno));
+ readahead_rsvd = get_huge_page_counter(hpage_size, HUGEPAGES_RSVD);
+ verbose_printf("Reserve count after readahead: %lu\n", readahead_rsvd);
+
+ /* Write the region */
+ memset(p, 1, hpage_size);
+
+ /* Free region */
+ munmap(p, hpage_size);
+ close(fd);
+ end_rsvd = get_huge_page_counter(hpage_size, HUGEPAGES_RSVD);
+ verbose_printf("Reserve count after close(): %lu\n", end_rsvd);
+
+ /* Reserve count should match initial reserve count */
+ if (end_rsvd != initial_rsvd)
+ FAIL("Reserve leaked: %lu != %lu\n", end_rsvd, initial_rsvd);
+
+ PASS();
+}
diff --git a/tests/run_tests.py b/tests/run_tests.py
index 6510787..ed246fc 100755
--- a/tests/run_tests.py
+++ b/tests/run_tests.py
@@ -479,7 +479,9 @@ def functional_tests():
do_test("brk_near_huge")
do_test("task-size-overrun")
do_test("stack_grow_into_huge")
+ do_test("readahead_reserve")
do_test("madvise_reserve")
+ do_test("fadvise_reserve")
# Tests requiring an active mount and hugepage COW
do_test("private")
------------------------------------------------------------------------------
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