How to use shared memory with huges pages

[marklakata]

We have a suite of applications that work fine running on the host, but I can't get it to work inside a container. The simplest test case is the following program. The following program runs fine on the host, but not in the container. It allocates 1 GiB of shared memory using huge pages.

In order for huge pages to work with shared memory, there are some other settings that need to be set, but they all seem to be set.

I'm running the container interactively like this

podman run --privileged --ipc=host -ti --group-add=1000 ourCustomImage /bin/bash

and build and run this:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/types.h>
#include <errno.h>

#define HUGETLB_SIZE (1024 * 1024 * 1024)

int main() {
    int shmid;
    key_t key = 0x50420051;

    /* Create the segment with huge pages */
    shmid = shmget(key, HUGETLB_SIZE,
                  SHM_HUGETLB | IPC_CREAT | IPC_EXCL | 0600 | SHM_NORESERVE);

    if (shmid == -1) {
        printf("shmget failed: %s\n", strerror(errno));
   }
}

and it always returns "shmget failed: Operation not permitted".

To use huge pages with shared memory, you need to be part of the hugetlb_shm_group, and I think it is set up correctly:

[root@2d19928b0464 shmem]# sysctl vm.hugetlb_shm_group
vm.hugetlb_shm_group = 1000
[root@2d19928b0464 shmem]# id
uid=0(root) gid=0(root) groups=0(root),1000

I don't know what else to try, or if it is even supported.