1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
|
/*
* Test rationale:
*
* Some kernel versions after hugepage demand allocation was added
* used a dubious heuristic to check if there was enough hugepage
* space available for a given mapping. The number of
* not-already-instantiated pages in the mapping was compared against
* the total hugepage free pool. It was very easy to confuse this
* heuristic into overcommitting by allocating hugepage memory in
* chunks, each less than the total available pool size but together
* more than available. This would generally lead to OOM SIGKILLs of
* one process or another when it tried to instantiate pages beyond
* the available pool.
*
*
* libhugetlbfs - Easy use of Linux hugepages
* Copyright (C) 2005-2006 David Gibson & Adam Litke, 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <signal.h>
#include <hugetlbfs.h>
#include "hugetests.h"
#define RANDOM_CONSTANT 0x1234ABCD
int main(int argc, char *argv[])
{
long hpage_size;
unsigned long totpages, chunk1, chunk2;
int fd;
void *p, *q;
pid_t child, ret;
int status;
test_init(argc, argv);
hpage_size = check_hugepagesize();
totpages = get_huge_page_counter(hpage_size, HUGEPAGES_FREE);
fd = hugetlbfs_unlinked_fd();
if (fd < 0)
FAIL("hugetlbfs_unlinked_fd()");
chunk1 = (totpages / 2) + 1;
chunk2 = totpages - chunk1 + 1;
verbose_printf("overcommit: %ld hugepages available: "
"chunk1=%ld chunk2=%ld\n", totpages, chunk1, chunk2);
p = mmap(NULL, chunk1*hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
fd, 0);
if (p == MAP_FAILED)
FAIL("mmap() chunk1: %s", strerror(errno));
q = mmap(NULL, chunk2*hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
fd, chunk1*hpage_size);
if (q == MAP_FAILED) {
if (errno != ENOMEM)
FAIL("mmap() chunk2: %s", strerror(errno));
else
PASS();
}
verbose_printf("Looks like we've overcommitted, testing...\n");
/* Looks like we're overcommited, but we need to confirm that
* this is bad. We touch it all in a child process because an
* overcommit will generally lead to a SIGKILL which we can't
* handle, of course. */
child = fork();
if (child < 0)
FAIL("fork(): %s", strerror(errno));
if (child == 0) {
memset(p, 0, chunk1*hpage_size);
memset(q, 0, chunk2*hpage_size);
exit(0);
}
ret = waitpid(child, &status, 0);
if (ret < 0)
FAIL("waitpid(): %s", strerror(errno));
if (WIFSIGNALED(status))
FAIL("Killed by signal \"%s\" due to overcommit",
strsignal(WTERMSIG(status)));
PASS();
}
|
