Re: [PATCH v2 06/11] mm/hmm: improve driver API to work and wait over a range v2

Ira Weiny
2019-03-29T02:50:18Z

On Thu, Mar 28, 2019 at 08:56:54PM -0400, Jerome Glisse wrote:
> On Thu, Mar 28, 2019 at 09:12:21AM -0700, Ira Weiny wrote:
> > On Mon, Mar 25, 2019 at 10:40:06AM -0400, Jerome Glisse wrote:
> > > From: Jérôme Glisse <jglisse@redhat.com>
> > >

[snip]

> > > +/*
> > > + * HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range
> > > + *
> > > + * When waiting for mmu notifiers we need some kind of time out otherwise we
> > > + * could potentialy wait for ever, 1000ms ie 1s sounds like a long time to
> > > + * wait already.
> > > + */
> > > +#define HMM_RANGE_DEFAULT_TIMEOUT 1000
> > > +
> > > /* This is a temporary helper to avoid merge conflict between trees. */
> > > +static inline bool hmm_vma_range_done(struct hmm_range *range)
> > > +{
> > > + bool ret = hmm_range_valid(range);
> > > +
> > > + hmm_range_unregister(range);
> > > + return ret;
> > > +}
> > > +
> > > static inline int hmm_vma_fault(struct hmm_range *range, bool block)
> > > {
> > > - long ret = hmm_range_fault(range, block);
> > > - if (ret == -EBUSY)
> > > - ret = -EAGAIN;
> > > - else if (ret == -EAGAIN)
> > > - ret = -EBUSY;
> > > - return ret < 0 ? ret : 0;
> > > + long ret;
> > > +
> > > + ret = hmm_range_register(range, range->vma->vm_mm,
> > > + range->start, range->end);
> > > + if (ret)
> > > + return (int)ret;
> > > +
> > > + if (!hmm_range_wait_until_valid(range, HMM_RANGE_DEFAULT_TIMEOUT)) {
> > > + up_read(&range->vma->vm_mm->mmap_sem);
> > > + return -EAGAIN;
> > > + }
> > > +
> > > + ret = hmm_range_fault(range, block);
> > > + if (ret <= 0) {
> > > + if (ret == -EBUSY || !ret) {
> > > + up_read(&range->vma->vm_mm->mmap_sem);
> > > + ret = -EBUSY;
> > > + } else if (ret == -EAGAIN)
> > > + ret = -EBUSY;
> > > + hmm_range_unregister(range);
> > > + return ret;
> > > + }
> > > + return 0;
> >
> > Is hmm_vma_fault() also temporary to keep the nouveau driver working? It looks
> > like it to me.
> >
> > This and hmm_vma_range_done() above are part of the old interface which is in
> > the Documentation correct? As stated above we should probably change that
> > documentation with this patch to ensure no new users of these 2 functions
> > appear.
>
> Ok will update the documentation, note that i already posted patches to use
> this new API see the ODP RDMA link in the cover letter.
>

Thanks, Sorry for my previous email on this patch. After looking more I see
that this is the old interface but this was not clear. And I have not had time
to follow the previous threads. I'm finding time to do this now...

Sorry,
Ira