Can mm_struct of a process be null?

[Daniel Baluta]

On Fri, Nov 15, 2013 at 6:24 PM, Paul Davies C <pauldaviesc at gmail.com> wrote:
> Hi,
>     I happen to find this code snippet in the kernel source :
>
>     struct mm_struct *mm=current->mm;
>
>     /* some other code */
>
>     if(mm){ /*<==Why is this here? */
>         /*read the contents by locking*/
>     }
>
> The if  checks whether the mm_struct of the current process is NULL or not.
> That means the mm_struct of a process can become NULL. How can that happen?

mm_struct points to a process address space. It is NULL for kernel threads.

Daniel.