Re: put_user_page() question

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On Wed, Feb 27, 2019 at 10:28:13AM -0800, Ira Weiny wrote:
> On Tue, Feb 26, 2019 at 05:22:44PM -0800, John Hubbard wrote:
> > On 2/26/19 5:10 PM, Ira Weiny wrote:
> > > John,
> > > 
> > > With your put_user_page patchset, Is there a reason you don't call
> > > put_user_page() in the 2 spots shown in the diff below?
> > > 
> > > And Jason, in the second case I find it odd that the driver needs to clear the
> > > invalidate_range() callback prior to the final ib_umem_odp_unmap_dma_pages()
> > > call such that put_user_page() is called.  I am correct that this is how the
> > > pages finally get put in the end?
> > > 
> > > Ira
> > > 
> > > diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
> > > index 730b2fa0942e..a63f5eda02ca 100644
> > > +++ b/drivers/infiniband/core/umem_odp.c
> > > @@ -687,7 +687,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
> > >                 if (ret < 0) {
> > >                         /* Release left over pages when handling errors. */
> > >                         for (++j; j < npages; ++j)
> > > -                               put_page(local_page_list[j]);
> > > +                               put_user_page(local_page_list[j]);
> > 
> > Hi Ira,
> > 
> > This one I somehow just overlooked. It definitely should have been a put_user_page()
> > call.
> > 
> > >                         break;
> > >                 }
> > >         }
> > > @@ -750,7 +750,7 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
> > >                         }
> > >                         /* on demand pinning support */
> > >                         if (!umem->context->invalidate_range)
> > > -                               put_page(page);
> > > +                               put_user_page(page);
> >  
> > 
> > ...and this one, I didn't recognize as being part of the pool of pages that
> > were acquired via get_user_pages().  But assuming that it is acquired via
> > get_user_pages(), then of course it also should be changed to put_user_page(),
> > you're right.
> 
> Yes I'm 99% sure this matches up with the get_user_pages_remote() in
> ib_umem_odp_map_dma_pages().  But the check for the
> invalidate_range() callback

invalidate_range does not change, it always set to something if the
driver supports ODP, and since this function accepts a ib_umem_odp it
cannot be called on non-ODP umem's..

In this case I assume the code can never be called??

Jason



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