Re: [PATCH v2 07/18] infiniband: set FOLL_PIN, FOLL_LONGTERM via pin_longterm_pages*()

[Ira Weiny <ira.weiny@intel.com>]

On Mon, Nov 04, 2019 at 04:57:38PM -0400, Jason Gunthorpe wrote:
> On Mon, Nov 04, 2019 at 12:48:13PM -0800, John Hubbard wrote:
> > On 11/4/19 12:33 PM, Jason Gunthorpe wrote:
> > ...
> > >> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
> > >> index 24244a2f68cc..c5a78d3e674b 100644
> > >> +++ b/drivers/infiniband/core/umem.c
> > >> @@ -272,11 +272,10 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
> > >>  
> > >>  	while (npages) {
> > >>  		down_read(&mm->mmap_sem);
> > >> -		ret = get_user_pages(cur_base,
> > >> +		ret = pin_longterm_pages(cur_base,
> > >>  				     min_t(unsigned long, npages,
> > >>  					   PAGE_SIZE / sizeof (struct page *)),
> > >> -				     gup_flags | FOLL_LONGTERM,
> > >> -				     page_list, NULL);
> > >> +				     gup_flags, page_list, NULL);
> > > 
> > > FWIW, this one should be converted to fast as well, I think we finally
> > > got rid of all the blockers for that?
> > > 
> > 
> > I'm not aware of any blockers on the gup.c end, anyway. The only broken thing we
> > have there is "gup remote + FOLL_LONGTERM". But we can do "gup fast + LONGTERM". 
> 
> I mean the use of the mmap_sem here is finally in a way where we can
> just delete the mmap_sem and use _fast

Yay!  I agree if we can do this we should.

Thanks,
Ira

>  
> ie, AFAIK there is no need for the mmap_sem to be held during
> ib_umem_add_sg_table()
> 
> This should probably be a standalone patch however
> 
> Jason