/******************************************************************************/
/* */
/* Copyright (s) Ying Han <yinghan@google.com>, 2009 */
/* */
/* This program is free software; you can redistribute it and/or modify */
/* it under the terms of the GNU General Public License as published by */
/* the Free Software Foundation; either version 2 of the License, or */
/* (at your option) any later version. */
/* */
/* This program 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 General Public License for more details. */
/* */
/* You should have received a copy of the GNU General Public License */
/* along with this program; if not, write to the Free Software */
/* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
/* */
/******************************************************************************/
/*
ftruncate-mmap: pages are lost after writing to mmaped file,
We triggered the failure during some internal experiment with
ftruncate/mmap/write/read sequence. And we found that some pages are
"lost" after writing to the mmaped file. which in the following test
cases (count >= 0).
First we deployed the test cases into group of machines and see about
>20% failure rate on average. Then, I did couple of experiment to try
to reproduce it on a single machine. what i found is that:
1. add a fsync after write the file, i can not reproduce this issue.
2. add memory pressure(mmap/mlock) while run the test in infinite
loop, the failure is reproduced quickly. ( background flushing ? )
The "bad pages" count differs each time from one digit to 4,5 digit
for 128M ftruncated file. and what i also found that the bad page
number are contiguous for each segment which total bad pages container
several segments. ext "1-4, 9-20, 48-50" ( batch flushing ? )
(The failure is reproduced based on 2.6.29-rc8, also happened on
2.6.18 kernel. . Here is the simple test case to reproduce it with
memory pressure. )
*/
#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include "test.h"
/* Extern Global Variables */
extern int tst_count;
/* Global Variables */
char *TCID = "mmap-corruption01"; /* test program identifier. */
int TST_TOTAL = 1; /* total number of tests in this file. */
long kMemSize = 128 << 20;
int kPageSize = 4096;
char *usage = "-h hours -m minutes -s secs\n";
int anyfail(void)
{
tst_brkm(TFAIL, tst_rmdir, "Test failed\n");
}
int main(int argc, char **argv)
{
char *progname;
int count = 0;
int i, c;
char *fname = "test.mmap-corruption";
char *mem;
unsigned long alarmtime = 0;
struct sigaction sa;
void finish(int sig);
progname = *argv;
while ((c = getopt(argc, argv, ":h:m:s:")) != -1) {
switch (c) {
case 'h':
alarmtime += atoi(optarg) * 60 * 60;
break;
case 'm':
alarmtime += atoi(optarg) * 60;
break;
case 's':
alarmtime += atoi(optarg);
break;
default:
(void)fprintf(stderr, "usage: %s %s\n", progname,
usage);
anyfail();
}
}
/*
* Plan for death by signal. User may have specified
* a time limit, in which case set an alarm and catch SIGALRM.
* Also catch and cleanup with SIGINT, SIGQUIT, and SIGTERM.
*/
sa.sa_handler = finish;
sa.sa_flags = 0;
if (sigemptyset(&sa.sa_mask)) {
perror("sigempty error");
exit(1);
}
if (sigaction(SIGINT, &sa, 0) == -1) {
perror("sigaction error SIGINT");
exit(1);
}
if (alarmtime) {
if (sigaction(SIGALRM, &sa, 0) == -1) {
perror("sigaction error");
exit(1);
}
(void)alarm(alarmtime);
printf("mmap-corruption will run for=> %ld, seconds\n",
alarmtime);
} else { //Run for 5 secs only
if (sigaction(SIGALRM, &sa, 0) == -1) {
perror("sigaction error");
exit(1);
}
(void)alarm(5);
printf("mmap-corruption will run for=> 5, seconds\n");
}
/* If we get a SIGQUIT or SIGTERM, clean up and exit immediately. */
sa.sa_handler = finish;
if (sigaction(SIGQUIT, &sa, 0) == -1) {
perror("sigaction error SIGQUIT");
exit(1);
}
if (sigaction(SIGTERM, &sa, 0) == -1) {
perror("sigaction error SIGTERM");
exit(1);
}
tst_tmpdir();
while (1) {
unlink(fname);
int fd = open(fname, O_CREAT | O_EXCL | O_RDWR, 0600);
ftruncate(fd, kMemSize);
mem =
mmap(0, kMemSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
0);
// Fill the memory with 1s.
memset(mem, 1, kMemSize);
for (i = 0; i < kMemSize; i++) {
int byte_good = mem[i] != 0;
if (!byte_good && ((i % kPageSize) == 0)) {
//printf("%d ", i / kPageSize);
count++;
}
}
munmap(mem, kMemSize);
close(fd);
unlink(fname);
if (count > 0) {
printf("Running %d bad page\n", count);
return 1;
}
count = 0;
}
return 0;
}
void finish(int sig)
{
printf("mmap-corruption PASSED\n");
exit(0);
}