Re: [PATCH 3/3] prctl_set_mm: downgrade mmap_sem to read lock

[Cyrill Gorcunov]

On Tue, Apr 30, 2019 at 11:55:45AM +0300, Kirill Tkhai wrote:
> > -	up_write(&mm->mmap_sem);
> > +	spin_unlock(&mm->arg_lock);
> > +	up_read(&mm->mmap_sem);
> >  	return error;
> 
> Hm, shouldn't spin_lock()/spin_unlock() pair go as a fixup to existing code
> in a separate patch? 
> 
> Without them, the existing code has a problem at least in get_mm_cmdline().

Seems reasonable to merge it into patch 1.