159 lines
4.3 KiB
Bash
Executable File
159 lines
4.3 KiB
Bash
Executable File
#!/bin/sh
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#
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# SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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#
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# Copyright (c) 2018 Dell EMC Isilon
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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# SUCH DAMAGE.
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#
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# Handle the race between fork/vm_object_split() and faults.
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#
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# If fault started before vmspace_fork() locked the map, and then during
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# fork, vm_map_copy_entry()->vm_object_split() is executed, it is
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# possible that the fault instantiate the page into the original object
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# when the page was already copied into the new object (see
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# vm_map_split() for the orig/new objects terminology). This can happen
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# if split found a busy page (e.g. from the fault) and slept dropping
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# the objects lock, which allows the swap pager to instantiate
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# read-behind pages for the fault. Then the restart of the scan can see
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# a page in the scanned range, where it was already copied to the upper
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# object.
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# No problems seen.
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. ../default.cfg
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dir=/tmp
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odir=`pwd`
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cd $dir
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sed '1,/^EOF/d' < $odir/$0 > $dir/template.c
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mycc -o template -Wall -Wextra -O0 -g template.c || exit 1
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rm -f template.c
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export MAXSWAPPCT=101
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(cd $odir/../testcases/swap; ./swap -t 5m -i 30 -l 100 -h) > /dev/null &
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$dir/template > /dev/null
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s=$?
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[ -f template.core -a $s -eq 0 ] &&
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{ ls -l template.core; mv template.core $dir; s=1; }
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wait
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rm -rf $dir/template
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exit $s
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EOF
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#include <sys/param.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <machine/atomic.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include <unistd.h>
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static volatile u_int *share;
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static volatile char *cp;
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#define PARALLEL 16
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#define RUNTIME (5 * 60)
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#define SYNC 0
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static void
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test(void)
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{
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size_t len;
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pid_t pid;
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int i;
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atomic_add_int(&share[SYNC], 1);
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while (share[SYNC] != PARALLEL)
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usleep(200);
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len = 1280 * PAGE_SIZE;
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if ((cp = mmap(NULL, len, PROT_READ | PROT_WRITE,
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MAP_ANON | MAP_PRIVATE, -1, 0)) == MAP_FAILED)
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err(1, "mmap");
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for (i = 0; i < (int)(len / sizeof(char)); i += PAGE_SIZE)
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cp[i] = 1;
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usleep(arc4random() % 500000);
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if ((pid = fork()) == 0) {
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usleep(arc4random() % 1000);
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for (i = 0; i < (int)(len); i += PAGE_SIZE)
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cp[i] = 2;
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fprintf(stdout, ".\n"); fflush(stdout);
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_exit(0);
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}
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if (pid == -1)
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err(1, "fork()");
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for (i = 0; i < (int)(len / sizeof(char)); i += PAGE_SIZE)
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cp[i] = 3;
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if (waitpid(pid, NULL, 0) != pid)
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err(1, "waitpid(%d)", pid);
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_exit(0);
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}
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int
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main(void)
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{
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pid_t pids[PARALLEL];
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size_t len;
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time_t start;
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int e, i, status;
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e = 0;
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len = PAGE_SIZE;
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if ((share = mmap(NULL, len, PROT_READ | PROT_WRITE,
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MAP_ANON | MAP_SHARED, -1, 0)) == MAP_FAILED)
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err(1, "mmap");
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start = time(NULL);
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while ((time(NULL) - start) < RUNTIME && e == 0) {
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share[SYNC] = 0;
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for (i = 0; i < PARALLEL; i++) {
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if ((pids[i] = fork()) == 0)
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test();
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if (pids[i] == -1)
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err(1, "fork()");
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}
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for (i = 0; i < PARALLEL; i++) {
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if (waitpid(pids[i], &status, 0) == -1)
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err(1, "waitpid(%d)", pids[i]);
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if (status != 0) {
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if (WIFSIGNALED(status))
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fprintf(stderr,
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"pid %d exit signal %d\n",
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pids[i], WTERMSIG(status));
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}
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e += status == 0 ? 0 : 1;
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}
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}
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return (e);
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}
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