/******************************************************************************/
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/* */
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/* Copyright (s) Ying Han <yinghan@google.com>, 2009 */
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/* */
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/* This program is free software; you can redistribute it and/or modify */
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/* it under the terms of the GNU General Public License as published by */
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/* the Free Software Foundation; either version 2 of the License, or */
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/* (at your option) any later version. */
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/* */
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/* This program is distributed in the hope that it will be useful, */
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/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
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/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See */
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/* the GNU General Public License for more details. */
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/* */
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/* You should have received a copy of the GNU General Public License */
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/* along with this program; if not, write to the Free Software */
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/* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
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/* */
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/******************************************************************************/
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/*
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ftruncate-mmap: pages are lost after writing to mmaped file,
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We triggered the failure during some internal experiment with
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ftruncate/mmap/write/read sequence. And we found that some pages are
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"lost" after writing to the mmaped file. which in the following test
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cases (count >= 0).
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First we deployed the test cases into group of machines and see about
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>20% failure rate on average. Then, I did couple of experiment to try
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to reproduce it on a single machine. what i found is that:
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1. add a fsync after write the file, i can not reproduce this issue.
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2. add memory pressure(mmap/mlock) while run the test in infinite
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loop, the failure is reproduced quickly. ( background flushing ? )
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The "bad pages" count differs each time from one digit to 4,5 digit
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for 128M ftruncated file. and what i also found that the bad page
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number are contiguous for each segment which total bad pages container
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several segments. ext "1-4, 9-20, 48-50" ( batch flushing ? )
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(The failure is reproduced based on 2.6.29-rc8, also happened on
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2.6.18 kernel. . Here is the simple test case to reproduce it with
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memory pressure. )
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*/
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#include <sys/mman.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <signal.h>
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#include "test.h"
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/* Extern Global Variables */
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extern int tst_count;
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/* Global Variables */
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char *TCID = "mmap-corruption01"; /* test program identifier. */
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int TST_TOTAL = 1; /* total number of tests in this file. */
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long kMemSize = 128 << 20;
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int kPageSize = 4096;
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char *usage = "-h hours -m minutes -s secs\n";
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int anyfail(void)
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{
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tst_brkm(TFAIL, tst_rmdir, "Test failed\n");
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}
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int main(int argc, char **argv)
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{
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char *progname;
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int count = 0;
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int i, c;
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char *fname = "test.mmap-corruption";
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char *mem;
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unsigned long alarmtime = 0;
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struct sigaction sa;
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void finish(int sig);
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progname = *argv;
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while ((c = getopt(argc, argv, ":h:m:s:")) != -1) {
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switch (c) {
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case 'h':
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alarmtime += atoi(optarg) * 60 * 60;
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break;
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case 'm':
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alarmtime += atoi(optarg) * 60;
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break;
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case 's':
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alarmtime += atoi(optarg);
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break;
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default:
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(void)fprintf(stderr, "usage: %s %s\n", progname,
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usage);
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anyfail();
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}
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}
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/*
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* Plan for death by signal. User may have specified
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* a time limit, in which case set an alarm and catch SIGALRM.
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* Also catch and cleanup with SIGINT, SIGQUIT, and SIGTERM.
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*/
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sa.sa_handler = finish;
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sa.sa_flags = 0;
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if (sigemptyset(&sa.sa_mask)) {
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perror("sigempty error");
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exit(1);
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}
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if (sigaction(SIGINT, &sa, 0) == -1) {
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perror("sigaction error SIGINT");
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exit(1);
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}
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if (alarmtime) {
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if (sigaction(SIGALRM, &sa, 0) == -1) {
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perror("sigaction error");
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exit(1);
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}
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(void)alarm(alarmtime);
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printf("mmap-corruption will run for=> %ld, seconds\n",
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alarmtime);
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} else { //Run for 5 secs only
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if (sigaction(SIGALRM, &sa, 0) == -1) {
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perror("sigaction error");
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exit(1);
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}
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(void)alarm(5);
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printf("mmap-corruption will run for=> 5, seconds\n");
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}
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/* If we get a SIGQUIT or SIGTERM, clean up and exit immediately. */
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sa.sa_handler = finish;
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if (sigaction(SIGQUIT, &sa, 0) == -1) {
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perror("sigaction error SIGQUIT");
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exit(1);
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}
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if (sigaction(SIGTERM, &sa, 0) == -1) {
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perror("sigaction error SIGTERM");
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exit(1);
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}
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tst_tmpdir();
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while (1) {
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unlink(fname);
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int fd = open(fname, O_CREAT | O_EXCL | O_RDWR, 0600);
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ftruncate(fd, kMemSize);
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mem =
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mmap(0, kMemSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
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0);
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// Fill the memory with 1s.
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memset(mem, 1, kMemSize);
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for (i = 0; i < kMemSize; i++) {
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int byte_good = mem[i] != 0;
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if (!byte_good && ((i % kPageSize) == 0)) {
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//printf("%d ", i / kPageSize);
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count++;
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}
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}
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munmap(mem, kMemSize);
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close(fd);
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unlink(fname);
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if (count > 0) {
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printf("Running %d bad page\n", count);
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return 1;
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}
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count = 0;
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}
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return 0;
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}
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void finish(int sig)
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{
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printf("mmap-corruption PASSED\n");
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exit(0);
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}
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