Re: [PATCH 5/5] mm/hmm: WARN on illegal ->sync_cpu_device_pagetables errors

Daniel Vetter
2019-08-15T07:14:21Z

On Wed, Aug 14, 2019 at 09:11:37PM -0300, Jason Gunthorpe wrote:
> On Wed, Aug 14, 2019 at 10:20:27PM +0200, Daniel Vetter wrote:
> > Similar to the warning in the mmu notifer, warning if an hmm mirror
> > callback gets it's blocking vs. nonblocking handling wrong, or if it
> > fails with anything else than -EAGAIN.
> >
> > Cc: Jason Gunthorpe <jgg@ziepe.ca>
> > Cc: Ralph Campbell <rcampbell@nvidia.com>
> > Cc: John Hubbard <jhubbard@nvidia.com>
> > Cc: Dan Williams <dan.j.williams@intel.com>
> > Cc: Dan Carpenter <dan.carpenter@oracle.com>
> > Cc: Matthew Wilcox <willy@infradead.org>
> > Cc: Arnd Bergmann <arnd@arndb.de>
> > Cc: Balbir Singh <bsingharora@gmail.com>
> > Cc: Ira Weiny <ira.weiny@intel.com>
> > Cc: Souptick Joarder <jrdr.linux@gmail.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: "Jérôme Glisse" <jglisse@redhat.com>
> > Cc: linux-mm@kvack.org
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > mm/hmm.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/mm/hmm.c b/mm/hmm.c
> > index 16b6731a34db..52ac59384268 100644
> > +++ b/mm/hmm.c
> > @@ -205,6 +205,9 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
> > ret = -EAGAIN;
> > break;
> > }
> > + WARN(ret, "%pS callback failed with %d in %sblockable context\n",
> > + mirror->ops->sync_cpu_device_pagetables, ret,
> > + update.blockable ? "" : "non-");
> > }
> > up_read(&hmm->mirrors_sem);
>
> Didn't I beat you to this?

Very much possible, I think I didn't rebase this to linux-next before
resending ... have an

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

in case you need.

Cheers, Daniel

>
> list_for_each_entry(mirror, &hmm->mirrors, list) {
> int rc;
>
> rc = mirror->ops->sync_cpu_device_pagetables(mirror, &update);
> if (rc) {
> if (WARN_ON(update.blockable || rc != -EAGAIN))
> continue;
> ret = -EAGAIN;
> break;
> }
> }
>
> Thanks,
> Jason

--
Daniel Vetter
Software Engineer, Intel Corporation