1 /* 2 * Copyright (C) 2010 Red Hat, Inc. 3 * This program is free software; you can redistribute it and/or 4 * modify it under the terms of version 2 of the GNU General Public 5 * License as published by the Free Software Foundation. 6 * 7 * This program is distributed in the hope that it would be useful, 8 * but WITHOUT ANY WARRANTY; without even the implied warranty of 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 10 * 11 * Further, this software is distributed without any warranty that it 12 * is free of the rightful claim of any third person regarding 13 * infringement or the like. Any license provided herein, whether 14 * implied or otherwise, applies only to this software file. Patent 15 * licenses, if any, provided herein do not apply to combinations of 16 * this program with other software, or any other product whatsoever. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write the Free Software 20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 21 * 02110-1301, USA. 22 */ 23 24 /* 25 * mmap/munmap /dev/zero: a common way of malloc()/free() anonymous 26 * memory on Solaris. 27 * 28 * The basic purpose of this is a to test if it is possible to map and 29 * unmap /dev/zero, and to read and write the mapping. Being inspired 30 * by two bugs in the past, the design of the test was added some 31 * variations based on the reproducers for them. It also accept an 32 * option to mmap/munmap anonymous pages. 33 * 34 * One is to trigger panic with transparent hugepage feature that 35 * split_huge_page is very strict in checking the rmap walk was 36 * perfect. Keep it strict because if page_mapcount isn't stable and 37 * just right, the __split_huge_page_refcount that follows the rmap 38 * walk could lead to erratic page_count()s for the subpages. The bug 39 * in fork lead to the rmap walk finding the parent huge-pmd twice 40 * instead of just one, because the anon_vma_chain objects of the 41 * child vma still point to the vma->vm_mm of the parent. That trips 42 * on the split_huge_page mapcount vs page_mapcount check leading to a 43 * BUG_ON. 44 * 45 * The other bug is mmap() of /dev/zero results in calling map_zero() 46 * which on RHEL5 maps the ZERO_PAGE in every PTE within that virtual 47 * address range. Since the application which maps a region from 5M to 48 * 16M in size is also multi-threaded the subsequent munmap() of 49 * /dev/zero results is TLB shootdowns to all other CPUs. When this 50 * happens thousands or millions of times the application performance 51 * is terrible. The mapping ZERO_PAGE in every pte within that virtual 52 * address range was an optimization to make the subsequent pagefault 53 * times faster on RHEL5 that has been removed/changed upstream. 54 */ 55 #include <sys/types.h> 56 #include <sys/stat.h> 57 #include <sys/wait.h> 58 #include <sys/mman.h> 59 #include <errno.h> 60 #include <unistd.h> 61 #include <stdlib.h> 62 #include <stdio.h> 63 #include <fcntl.h> 64 #include "test.h" 65 #include "config.h" 66 67 #define SIZE (5*1024*1024) 68 #define PATH_KSM "/sys/kernel/mm/ksm/" 69 70 char *TCID = "mmap10"; 71 int TST_TOTAL = 1; 72 73 static int fd, opt_anon, opt_ksm; 74 static long ps; 75 static char *x; 76 77 void setup(void); 78 void cleanup(void); 79 void mmapzero(void); 80 void help(void); 81 82 static option_t options[] = { 83 {"a", &opt_anon, NULL}, 84 {"s", &opt_ksm, NULL}, 85 {NULL, NULL, NULL} 86 }; 87 88 int main(int argc, char *argv[]) 89 { 90 int lc; 91 92 tst_parse_opts(argc, argv, options, help); 93 94 if (opt_ksm) { 95 if (access(PATH_KSM, F_OK) == -1) 96 tst_brkm(TCONF, NULL, 97 "KSM configuration is not enabled"); 98 #ifdef HAVE_MADV_MERGEABLE 99 tst_resm(TINFO, "add to KSM regions."); 100 #else 101 tst_brkm(TCONF, NULL, "MADV_MERGEABLE missing in sys/mman.h"); 102 #endif 103 } 104 if (opt_anon) 105 tst_resm(TINFO, "use anonymous pages."); 106 else 107 tst_resm(TINFO, "use /dev/zero."); 108 109 setup(); 110 111 tst_resm(TINFO, "start tests."); 112 for (lc = 0; TEST_LOOPING(lc); lc++) { 113 tst_count = 0; 114 mmapzero(); 115 } 116 117 cleanup(); 118 tst_exit(); 119 } 120 121 void mmapzero(void) 122 { 123 int n; 124 125 if (opt_anon) { 126 x = mmap(NULL, SIZE + SIZE - ps, PROT_READ | PROT_WRITE, 127 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 128 } else { 129 if ((fd = open("/dev/zero", O_RDWR, 0666)) < 0) 130 tst_brkm(TBROK | TERRNO, cleanup, "open"); 131 x = mmap(NULL, SIZE + SIZE - ps, PROT_READ | PROT_WRITE, 132 MAP_PRIVATE, fd, 0); 133 } 134 if (x == MAP_FAILED) 135 tst_brkm(TFAIL | TERRNO, cleanup, "mmap"); 136 #ifdef HAVE_MADV_MERGEABLE 137 if (opt_ksm) { 138 if (madvise(x, SIZE + SIZE - ps, MADV_MERGEABLE) == -1) 139 tst_brkm(TBROK | TERRNO, cleanup, "madvise"); 140 } 141 #endif 142 x[SIZE] = 0; 143 144 switch (n = fork()) { 145 case -1: 146 tst_brkm(TBROK | TERRNO, cleanup, "fork"); 147 case 0: 148 if (munmap(x + SIZE + ps, SIZE - ps - ps) == -1) 149 tst_brkm(TFAIL | TERRNO, cleanup, "munmap"); 150 exit(0); 151 default: 152 break; 153 } 154 155 switch (n = fork()) { 156 case -1: 157 tst_brkm(TBROK | TERRNO, cleanup, "fork"); 158 case 0: 159 if (munmap(x + SIZE + ps, SIZE - ps - ps) == -1) 160 tst_brkm(TFAIL | TERRNO, cleanup, 161 "subsequent munmap #1"); 162 exit(0); 163 default: 164 switch (n = fork()) { 165 case -1: 166 tst_brkm(TBROK | TERRNO, cleanup, "fork"); 167 case 0: 168 if (munmap(x + SIZE + ps, SIZE - ps - ps) == -1) 169 tst_brkm(TFAIL | TERRNO, cleanup, 170 "subsequent munmap #2"); 171 exit(0); 172 default: 173 break; 174 } 175 break; 176 } 177 178 if (munmap(x, SIZE + SIZE - ps) == -1) 179 tst_resm(TFAIL | TERRNO, "munmap all"); 180 181 while (waitpid(-1, &n, WUNTRACED | WCONTINUED) > 0) 182 if (WEXITSTATUS(n) != 0) 183 tst_resm(TFAIL, "child exit status is %d", 184 WEXITSTATUS(n)); 185 } 186 187 void cleanup(void) 188 { 189 } 190 191 void setup(void) 192 { 193 tst_require_root(); 194 195 tst_sig(FORK, DEF_HANDLER, cleanup); 196 TEST_PAUSE; 197 198 if ((ps = sysconf(_SC_PAGESIZE)) == -1) 199 tst_brkm(TBROK | TERRNO, cleanup, "sysconf(_SC_PAGESIZE)"); 200 } 201 202 void help(void) 203 { 204 printf(" -a Test anonymous pages\n"); 205 printf(" -s Add to KSM regions\n"); 206 } 207
