Re: [PATCH v7 18/27] mm: Introduce do_mmap_locked()

[Peter Zijlstra]

On Fri, Jun 07, 2019 at 09:43:22AM +0200, Peter Zijlstra wrote:
> On Thu, Jun 06, 2019 at 01:06:37PM -0700, Yu-cheng Yu wrote:
> > There are a few places that need do_mmap() with mm->mmap_sem held.
> > Create an in-line function for that.
> > 
> > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> > ---
> >  include/linux/mm.h | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> > 
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 398f1e1c35e5..7cf014604848 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -2411,6 +2411,24 @@ static inline void mm_populate(unsigned long addr, unsigned long len)
> >  static inline void mm_populate(unsigned long addr, unsigned long len) {}
> >  #endif
> >  
> > +static inline unsigned long do_mmap_locked(unsigned long addr,
> > +	unsigned long len, unsigned long prot, unsigned long flags,
> > +	vm_flags_t vm_flags)
> > +{
> > +	struct mm_struct *mm = current->mm;
> > +	unsigned long populate;
> > +
> > +	down_write(&mm->mmap_sem);
> > +	addr = do_mmap(NULL, addr, len, prot, flags, vm_flags, 0,
> > +		       &populate, NULL);
> 
> Funny thing how do_mmap() takes a file pointer as first argument and
> this thing explicitly NULLs that. That more or less invalidates the name
> do_mmap_locked().
> 
> > +	up_write(&mm->mmap_sem);
> > +
> > +	if (populate)
> > +		mm_populate(addr, populate);
> > +
> > +	return addr;
> > +}

You also don't retain that last @uf argument.

I'm thikning you're better off adding a helper to the cet.c file; call
it cet_mmap() or whatever.