int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
{
	long allowed;
	unsigned long bytes_failed;

	vm_acct_memory(pages);

	/*
	 * Sometimes we want to use more memory than we have
	 */
	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
		return 0;

	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
		if (pages > totalram_pages() + total_swap_pages)
			goto error;
		return 0;
	}

	allowed = vm_commit_limit();
	/*
	 * Reserve some for root
	 */
	if (!cap_sys_admin)
		allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);

	/*
	 * Don't let a single process grow so big a user can't recover
	 */
	if (mm) {
		long reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);

		allowed -= min_t(long, mm->total_vm / 32, reserve);
	}

	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
		return 0;
error:
	bytes_failed = pages << PAGE_SHIFT;
	pr_warn_ratelimited("%s: pid: %d, comm: %s, bytes: %lu not enough memory for the allocation\n",
			    __func__, current->pid, current->comm, bytes_failed);
	vm_unacct_memory(pages);

	return -ENOMEM;
}

Warm-up