# Re: \[PATCH 13/18\] exec: make exec path waiting for mmap\_sem killable

- From: Oleg Nesterov \<oleg@redhat.com\>
- Date: 2016-02-29 18:10:32 
- List: linux-arch
- Page: https://ratatoskr.run/linux-arch/2016/02/4697191
- Thread: https://ratatoskr.run/linux-mm/2016/02/4696944/t.md

```text
On 02/29, Michal Hocko wrote:
>
> On Mon 29-02-16 18:23:34, Oleg Nesterov wrote:
> > On 02/29, Michal Hocko wrote:
> > >
> > > @@ -267,7 +267,10 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
> > >  	if (!vma)
> > >  		return -ENOMEM;
> > >
> > > -	down_write(&mm->mmap_sem);
> > > +	if (down_write_killable(&mm->mmap_sem)) {
> > > +		err = -EINTR;
> > > +		goto err_free;
> > > +	}
> > >  	vma->vm_mm = mm;
> >
> > I won't argue, but this looks unnecessary. Nobody else can see this new mm,
> > down_write() can't block.
> >
> > In fact I think we can just remove down_write/up_write here. Except perhaps
> > there is lockdep_assert_held() somewhere in these paths.
>
> This is what I had initially but then I've noticed that mm_alloc() does
> mm_init(current)->init_new_context(current)

yes, and init_new_context() is arch dependant...

> code doesn't seem much harder to follow, the callers are already
> handling all error paths so I guess it would be better to simply move on
> this.

Yes, agreed, please forget.

Oleg.
```