Is there a maximum number of continuous pages per process in Linux? If so, how to set it to unlimited?

Question

The following code will generate errno 12 cannot allocate memory

#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <memory.h>
#include <errno.h>
int main()
{
    char* p;
    for (size_t i = 0; i < 0x10000; i++)
    {
        char* addr = (char*)0xAAA00000000uL - i * 0x2000;
        p = mmap(addr, 0x1000,
            PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
        if (p != addr) {
            printf("%lu %d\n", i, errno);
            getchar();
            return 1;
        }
        memset(p, 'A' + (i % 26), 0x1000);
    }
    return 0;
}

The output is 65510 12 on my machine.

However, if we change size of each page from 0x1000 to 0x2000, the allocation will be successful, even if it is using more memory. The only difference I think is the number of continuous pages, is there a limitation on this? If so, how to set it to unlimited?

Answer 1

It seems that setting /proc/sys/vm/max_map_count to a larger number solves the problem. Reference: How much memory could vm use