get_killed.c

#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

size_t memtotal() {
    char buf[200];
    size_t ret;
    FILE* meminfo = fopen("/proc/meminfo", "r");
    if (!meminfo) {
        perror("fopen");
        exit(1);
    }
    while(fgets(buf, sizeof(buf), meminfo)) {
        int scan = sscanf(buf, "MemTotal: %zu kB", &ret);
        if (scan == 1) {
            ret = ret << 10; //kB -> B
            goto cleanup;
        }
    }
    exit(1);
cleanup:
    fclose(meminfo);
    return ret;
}

// The kernel won't hand us enough address space to consume all of the system's
// memory in one go, but it's happy enough to give us half that amount twice.
#define SPLIT 2

int main(int argc, char** argv) {
    int i;
    size_t memsize = memtotal();
    void *blocks[SPLIT];
    printf("Total mem %zd bytes, let's get killed!\n", memsize);
    for (i = 0; i < SPLIT; i++) {
        void *blk = mmap(NULL, memsize / SPLIT,
                         PROT_WRITE | PROT_READ,
                         MAP_SHARED | MAP_ANONYMOUS,
                         -1, 0);
        if (blk == MAP_FAILED) {
            perror("mmap");
            exit(1);
        }
        blocks[i]=blk;
    }
    printf("Mapped enough address space to fill memory, now to touch it!\n");
    for (i = 0; i < SPLIT; i++)
        memset(blocks[i], 0xff, memsize / SPLIT);
    return 0;
}