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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (c) 2020 SUSE LLC <mdoucha@suse.cz>
*/
#include <unistd.h>
#include <limits.h>
#include <sys/sysinfo.h>
#include <stdlib.h>
#define TST_NO_DEFAULT_MAIN
#include "tst_test.h"
#define BLOCKSIZE (16 * 1024 * 1024)
void tst_pollute_memory(size_t maxsize, int fillchar)
{
size_t i, map_count = 0, safety = 0, blocksize = BLOCKSIZE;
void **map_blocks;
struct sysinfo info;
SAFE_SYSINFO(&info);
safety = 4096 * SAFE_SYSCONF(_SC_PAGESIZE) / info.mem_unit;
if (info.freeswap > safety)
safety = 0;
/* Not enough free memory to avoid invoking OOM killer */
if (info.freeram <= safety)
return;
if (!maxsize)
maxsize = SIZE_MAX;
if (info.freeram - safety < maxsize / info.mem_unit)
maxsize = (info.freeram - safety) * info.mem_unit;
blocksize = MIN(maxsize, blocksize);
map_count = maxsize / blocksize;
map_blocks = SAFE_MALLOC(map_count * sizeof(void *));
/*
* Keep allocating until the first failure. The address space may be
* too fragmented or just smaller than maxsize.
*/
for (i = 0; i < map_count; i++) {
map_blocks[i] = mmap(NULL, blocksize, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (map_blocks[i] == MAP_FAILED) {
map_count = i;
break;
}
memset(map_blocks[i], fillchar, blocksize);
}
for (i = 0; i < map_count; i++)
SAFE_MUNMAP(map_blocks[i], blocksize);
free(map_blocks);
}
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