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
> > --- a/drivers/infiniband/core/umem_odp.c
> > +++ 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
threw me a bit. Hence my question to Jason regarding the requirements of the
driver when calling unmap. It seems like if the driver has not cleared the
invalidate callback then there could be a potential for an unmatched
GUP depending on what the driver is doing with the umem. But I'm
not 100% sure I've found a problem.
Ira
>
> Glad you're taking a hard look at this!
>
>
> thanks,
> --
> John Hubbard
> NVIDIA
