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      1 /*
      2  * Copyright (c) 2015-2017 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 2 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
     12  * the GNU General Public License for more details.
     13  */
     14 
     15 /*
     16  * DESCRIPTION
     17  *
     18  *   There is a race condition if we map a same file on different processes.
     19  *   Region tracking is protected by mmap_sem and hugetlb_instantiation_mutex.
     20  *   When we do mmap, we don't grab a hugetlb_instantiation_mutex, but only
     21  *   mmap_sem (exclusively).  This doesn't prevent other tasks from modifying
     22  *   the region structure, so it can be modified by two processes concurrently.
     23  *
     24  *   This bug was fixed on stable kernel by commits:
     25  *       f522c3ac00(mm, hugetlb: change variable name reservations to resv)
     26  *       9119a41e90(mm, hugetlb: unify region structure handling)
     27  *       7b24d8616b(mm, hugetlb: fix race in region tracking)
     28  *       1406ec9ba6(mm, hugetlb: improve, cleanup resv_map parameters)
     29  *
     30  * AUTHOR:
     31  *    Herton R. Krzesinski <herton (at) redhat.com>
     32  *    Li Wang <liwang (at) redhat.com>
     33  */
     34 
     35 #define _GNU_SOURCE
     36 #include <pthread.h>
     37 #include <stdio.h>
     38 #include "hugetlb.h"
     39 #include "lapi/mmap.h"
     40 
     41 static long hpage_size;
     42 static long hugepages;
     43 
     44 struct mp {
     45 	char *addr;
     46 	int sz;
     47 };
     48 
     49 #define ARSZ 50
     50 #define LOOP 5
     51 
     52 static void setup(void)
     53 {
     54 	save_nr_hugepages();
     55 
     56 	hpage_size = SAFE_READ_MEMINFO("Hugepagesize:") * 1024;
     57 
     58 	hugepages = (ARSZ + 1) * LOOP;
     59 
     60 	if (hugepages * SAFE_READ_MEMINFO("Hugepagesize:") > SAFE_READ_MEMINFO("MemTotal:"))
     61 		tst_brk(TCONF, "System RAM is not enough to test.");
     62 
     63 	set_sys_tune("nr_hugepages", hugepages, 1);
     64 }
     65 
     66 static void cleanup(void)
     67 {
     68 	restore_nr_hugepages();
     69 }
     70 
     71 static void *thr(void *arg)
     72 {
     73 	struct mp *mmap_sz = arg;
     74 	int i, lim, a, b, c;
     75 
     76 	srand(time(NULL));
     77 	lim = rand() % 10;
     78 	for (i = 0; i < lim; i++) {
     79 		a = rand() % mmap_sz->sz;
     80 		for (c = 0; c <= a; c++) {
     81 			b = rand() % mmap_sz->sz;
     82 			*(mmap_sz->addr + b * hpage_size) = rand();
     83 		}
     84 	}
     85 	return NULL;
     86 }
     87 
     88 static void do_mmap(unsigned int j LTP_ATTRIBUTE_UNUSED)
     89 {
     90 	int i, sz = ARSZ + 1;
     91 	void *addr, *new_addr;
     92 	struct mp mmap_sz[ARSZ];
     93 	pthread_t tid[ARSZ];
     94 
     95 	addr = mmap(NULL, sz * hpage_size,
     96 			PROT_READ | PROT_WRITE,
     97 			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
     98 			-1, 0);
     99 
    100 	if (addr == MAP_FAILED) {
    101 		if (errno == ENOMEM) {
    102 			tst_brk(TCONF,
    103 				"Cannot allocate hugepage, memory too fragmented?");
    104 		}
    105 
    106 		tst_brk(TBROK | TERRNO, "Cannot allocate hugepage");
    107 	}
    108 
    109 	for (i = 0; i < ARSZ; ++i, --sz) {
    110 		mmap_sz[i].sz = sz;
    111 		mmap_sz[i].addr = addr;
    112 
    113 		TEST(pthread_create(&tid[i], NULL, thr, &mmap_sz[i]));
    114 		if (TST_RET)
    115 			tst_brk(TBROK | TRERRNO,
    116 					"pthread_create failed");
    117 
    118 		new_addr = mmap(addr, (sz - 1) * hpage_size,
    119 				PROT_READ | PROT_WRITE,
    120 				MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED,
    121 				-1, 0);
    122 
    123 		if (new_addr == MAP_FAILED)
    124 			tst_brk(TFAIL | TERRNO, "mmap failed");
    125 
    126 		addr = new_addr;
    127 	}
    128 
    129 	for (i = 0; i < ARSZ; ++i) {
    130 		TEST(pthread_join(tid[i], NULL));
    131 		if (TST_RET)
    132 			tst_brk(TBROK | TRERRNO,
    133 					"pthread_join failed");
    134 	}
    135 
    136 	if (munmap(addr, sz * hpage_size) == -1)
    137 		tst_brk(TFAIL | TERRNO, "huge munmap failed");
    138 
    139 	tst_res(TPASS, "No regression found.");
    140 }
    141 
    142 static struct tst_test test = {
    143 	.min_kver = "2.6.32",
    144 	.needs_root = 1,
    145 	.tcnt = LOOP,
    146 	.needs_tmpdir = 1,
    147 	.test = do_mmap,
    148 	.setup = setup,
    149 	.cleanup = cleanup,
    150 };
    151