[Devel] Re: [PATCH 11/11] protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs

[David Rientjes]

On Mon, 25 Jun 2012, Glauber Costa wrote:

> diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
> index ccc1899..914ec07 100644
> --- a/include/linux/thread_info.h
> +++ b/include/linux/thread_info.h
> @@ -61,6 +61,12 @@ extern long do_no_restart_syscall(struct restart_block *parm);
>  # define THREADINFO_GFP		(GFP_KERNEL | __GFP_NOTRACK)
>  #endif
>  
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
> +# define THREADINFO_GFP_ACCOUNTED (THREADINFO_GFP | __GFP_KMEMCG)
> +#else
> +# define THREADINFO_GFP_ACCOUNTED (THREADINFO_GFP)
> +#endif
> +

This type of requirement is going to become nasty very quickly if nobody 
can use __GFP_KMEMCG without testing for CONFIG_CGROUP_MEM_RES_CTLR_KMEM.  
Perhaps define __GFP_KMEMCG to be 0x0 if it's not enabled, similar to how 
kmemcheck does?