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      1 /*
      2  *  Copyright (c) 2015 Red Hat, Inc.
      3  *
      4  * This program is free software: you can redistribute it and/or modify
      5  * it under the terms of the GNU General Public License as published by
      6  * the Free Software Foundation, either version 3 of the License, or
      7  * (at your option) any later version.
      8  *
      9  * This program is distributed in the hope that it will be useful,
     10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     12  * GNU General Public License for more details.
     13  *
     14  * You should have received a copy of the GNU General Public License
     15  * along with this program. If not, see <http://www.gnu.org/licenses/>.
     16  */
     17 
     18 /*
     19  * DESCRIPTION
     20  *
     21  *   There is a race condition if we map a same file on different processes.
     22  *   Region tracking is protected by mmap_sem and hugetlb_instantiation_mutex.
     23  *   When we do mmap, we don't grab a hugetlb_instantiation_mutex, but only
     24  *   mmap_sem (exclusively).  This doesn't prevent other tasks from modifying
     25  *   the region structure, so it can be modified by two processes concurrently.
     26  *
     27  *   This bug was fixed on stable kernel by commits:
     28  *       f522c3ac00(mm, hugetlb: change variable name reservations to resv)
     29  *       9119a41e90(mm, hugetlb: unify region structure handling)
     30  *       7b24d8616b(mm, hugetlb: fix race in region tracking)
     31  *       1406ec9ba6(mm, hugetlb: improve, cleanup resv_map parameters)
     32  *
     33  * AUTHOR:
     34  *    Herton R. Krzesinski <herton (at) redhat.com>
     35  *    Li Wang <liwang (at) redhat.com>
     36  */
     37 
     38 #define _GNU_SOURCE
     39 #include <errno.h>
     40 #include <pthread.h>
     41 #include <stdio.h>
     42 #include <stdlib.h>
     43 #include <sys/mman.h>
     44 #include <sys/types.h>
     45 #include <unistd.h>
     46 
     47 #include "test.h"
     48 #include "mem.h"
     49 #include "hugetlb.h"
     50 #include "lapi/mmap.h"
     51 
     52 char *TCID = "hugemmap06";
     53 int TST_TOTAL = 5;
     54 
     55 static long hpage_size;
     56 static long hugepages;
     57 
     58 struct mp {
     59 	char *addr;
     60 	int sz;
     61 };
     62 
     63 #define ARSZ 50
     64 
     65 void setup(void)
     66 {
     67 	tst_require_root();
     68 	check_hugepage();
     69 
     70 	/* MAP_HUGETLB check */
     71 	if ((tst_kvercmp(2, 6, 32)) < 0) {
     72 		tst_brkm(TCONF, NULL, "This test can only run on kernels "
     73 			"that are 2.6.32 or higher");
     74 	}
     75 
     76 	hpage_size = read_meminfo("Hugepagesize:") * 1024;
     77 	orig_hugepages = get_sys_tune("nr_hugepages");
     78 
     79 	hugepages = (ARSZ + 1) * TST_TOTAL;
     80 
     81 	if (hugepages * read_meminfo("Hugepagesize:") > read_meminfo("MemTotal:"))
     82 		tst_brkm(TCONF, NULL, "System RAM is not enough to test.");
     83 
     84 	set_sys_tune("nr_hugepages", hugepages, 1);
     85 
     86 	TEST_PAUSE;
     87 }
     88 
     89 void cleanup(void)
     90 {
     91 	set_sys_tune("nr_hugepages", orig_hugepages, 0);
     92 }
     93 
     94 void *thr(void *arg)
     95 {
     96 	struct mp *mmap_sz = arg;
     97 	int i, lim, a, b, c;
     98 
     99 	srand(time(NULL));
    100 	lim = rand() % 10;
    101 	for (i = 0; i < lim; i++) {
    102 		a = rand() % mmap_sz->sz;
    103 		for (c = 0; c <= a; c++) {
    104 			b = rand() % mmap_sz->sz;
    105 			*(mmap_sz->addr + b * hpage_size) = rand();
    106 		}
    107 	}
    108 	return NULL;
    109 }
    110 
    111 void do_mmap(void)
    112 {
    113 	int i, sz = ARSZ + 1;
    114 	void *addr, *new_addr;
    115 	struct mp mmap_sz[ARSZ];
    116 	pthread_t tid[ARSZ];
    117 
    118 	addr = mmap(NULL, sz * hpage_size,
    119 			PROT_READ | PROT_WRITE,
    120 			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
    121 			-1, 0);
    122 
    123 	if (addr == MAP_FAILED) {
    124 		if (errno == ENOMEM) {
    125 			tst_brkm(TCONF, cleanup,
    126 				"Cannot allocate hugepage, memory too fragmented?");
    127 		}
    128 
    129 		tst_brkm(TBROK | TERRNO, cleanup, "Cannot allocate hugepage");
    130 	}
    131 
    132 	for (i = 0; i < ARSZ; ++i, --sz) {
    133 		mmap_sz[i].sz = sz;
    134 		mmap_sz[i].addr = addr;
    135 
    136 		TEST(pthread_create(&tid[i], NULL, thr, &mmap_sz[i]));
    137 		if (TEST_RETURN)
    138 			tst_brkm(TBROK | TRERRNO, cleanup,
    139 					"pthread_create failed");
    140 
    141 		new_addr = mmap(addr, (sz - 1) * hpage_size,
    142 				PROT_READ | PROT_WRITE,
    143 				MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED,
    144 				-1, 0);
    145 
    146 		if (new_addr == MAP_FAILED)
    147 			tst_brkm(TFAIL | TERRNO, cleanup, "mmap failed");
    148 
    149 		addr = new_addr;
    150 	}
    151 
    152 	for (i = 0; i < ARSZ; ++i) {
    153 		TEST(pthread_join(tid[i], NULL));
    154 		if (TEST_RETURN)
    155 			tst_brkm(TBROK | TRERRNO, cleanup,
    156 					"pthread_join failed");
    157 	}
    158 
    159 	if (munmap(addr, sz * hpage_size) == -1)
    160 		tst_brkm(TFAIL | TERRNO, cleanup, "huge munmap failed");
    161 }
    162 
    163 int main(int ac, char **av)
    164 {
    165 	int lc, i;
    166 
    167 	tst_parse_opts(ac, av, NULL, NULL);
    168 
    169 	setup();
    170 
    171 	for (lc = 0; TEST_LOOPING(lc); lc++) {
    172 		tst_count = 0;
    173 
    174 		for (i = 0; i < TST_TOTAL; i++)
    175 			do_mmap();
    176 
    177 		tst_resm(TPASS, "No regression found.");
    178 	}
    179 
    180 	cleanup();
    181 	tst_exit();
    182 }
    183