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From:   Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sat, 10 Oct 2020 23:32:03 +0200
Message-ID: <CAKMK7uG_kBpmuQDRgKdyh8SycFDhE7kuB2MEOsx+D5wRmerWKA@mail.gmail.com>
Subject: Re: [PATCH v2 03/17] misc/habana: Stop using frame_vector helpers
To:     Oded Gabbay <oded.gabbay@gmail.com>
Cc:     DRI Development <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        KVM list <kvm@vger.kernel.org>, linux-mm <linux-mm@kvack.org>,
        "list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>, Joerg
        Roedel <joro@8bytes.org>," <linux-arm-kernel@lists.infradead.org>,
        linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
        Linux Media Mailing List <linux-media@vger.kernel.org>,
        linux-s390 <linux-s390@vger.kernel.org>,
        Daniel Vetter <daniel.vetter@intel.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Andrew Morton <akpm@linux-foundation.org>,
        John Hubbard <jhubbard@nvidia.com>,
        =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        Jan Kara <jack@suse.cz>,
        Dan Williams <dan.j.williams@intel.com>,
        Omer Shpigelman <oshpigelman@habana.ai>,
        Ofir Bitton <obitton@habana.ai>,
        Tomer Tayar <ttayar@habana.ai>,
        Moti Haimovski <mhaimovski@habana.ai>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Pawel Piskorski <ppiskorski@habana.ai>
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On Sat, Oct 10, 2020 at 10:27 PM Oded Gabbay <oded.gabbay@gmail.com> wrote:
>
> On Fri, Oct 9, 2020 at 10:59 AM Daniel Vetter <daniel.vetter@ffwll.ch> wr=
ote:
> >
> > All we need are a pages array, pin_user_pages_fast can give us that
> > directly. Plus this avoids the entire raw pfn side of get_vaddr_frames.
> >
> Thanks for the patch Daniel.
>
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: Jason Gunthorpe <jgg@ziepe.ca>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: John Hubbard <jhubbard@nvidia.com>
> > Cc: J=C3=A9r=C3=B4me Glisse <jglisse@redhat.com>
> > Cc: Jan Kara <jack@suse.cz>
> > Cc: Dan Williams <dan.j.williams@intel.com>
> > Cc: linux-mm@kvack.org
> > Cc: linux-arm-kernel@lists.infradead.org
> > Cc: linux-samsung-soc@vger.kernel.org
> > Cc: linux-media@vger.kernel.org
> > Cc: Oded Gabbay <oded.gabbay@gmail.com>
> > Cc: Omer Shpigelman <oshpigelman@habana.ai>
> > Cc: Ofir Bitton <obitton@habana.ai>
> > Cc: Tomer Tayar <ttayar@habana.ai>
> > Cc: Moti Haimovski <mhaimovski@habana.ai>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: Pawel Piskorski <ppiskorski@habana.ai>
> > --
> > v2: Use unpin_user_pages_dirty_lock (John)
> > ---
> >  drivers/misc/habanalabs/Kconfig             |  1 -
> >  drivers/misc/habanalabs/common/habanalabs.h |  3 +-
> >  drivers/misc/habanalabs/common/memory.c     | 49 ++++++++-------------
> >  3 files changed, 20 insertions(+), 33 deletions(-)
> >
> > diff --git a/drivers/misc/habanalabs/Kconfig b/drivers/misc/habanalabs/=
Kconfig
> > index 8eb5d38c618e..2f04187f7167 100644
> > --- a/drivers/misc/habanalabs/Kconfig
> > +++ b/drivers/misc/habanalabs/Kconfig
> > @@ -6,7 +6,6 @@
> >  config HABANA_AI
> >         tristate "HabanaAI accelerators (habanalabs)"
> >         depends on PCI && HAS_IOMEM
> > -       select FRAME_VECTOR
> >         select DMA_SHARED_BUFFER
> >         select GENERIC_ALLOCATOR
> >         select HWMON
> > diff --git a/drivers/misc/habanalabs/common/habanalabs.h b/drivers/misc=
/habanalabs/common/habanalabs.h
> > index edbd627b29d2..c1b3ad613b15 100644
> > --- a/drivers/misc/habanalabs/common/habanalabs.h
> > +++ b/drivers/misc/habanalabs/common/habanalabs.h
> > @@ -881,7 +881,8 @@ struct hl_ctx_mgr {
> >  struct hl_userptr {
> >         enum vm_type_t          vm_type; /* must be first */
> >         struct list_head        job_node;
> > -       struct frame_vector     *vec;
> > +       struct page             **pages;
> > +       unsigned int            npages;
> Can you please update the kerneldoc comment section of this structure
> according to your changes ?

Apologies I missed the nice kerneldoc. I'll fix that in the next round.


> >         struct sg_table         *sgt;
> >         enum dma_data_direction dir;
> >         struct list_head        debugfs_list;
> > diff --git a/drivers/misc/habanalabs/common/memory.c b/drivers/misc/hab=
analabs/common/memory.c
> > index 5ff4688683fd..327b64479f97 100644
> > --- a/drivers/misc/habanalabs/common/memory.c
> > +++ b/drivers/misc/habanalabs/common/memory.c
> > @@ -1281,45 +1281,41 @@ static int get_user_memory(struct hl_device *hd=
ev, u64 addr, u64 size,
> >                 return -EFAULT;
> >         }
> >
> > -       userptr->vec =3D frame_vector_create(npages);
> > -       if (!userptr->vec) {
> > +       userptr->pages =3D kvmalloc_array(npages, sizeof(*userptr->page=
s),
> > +                                       GFP_KERNEL);
> > +       if (!userptr->pages) {
> >                 dev_err(hdev->dev, "Failed to create frame vector\n");
> >                 return -ENOMEM;
> >         }
> >
> > -       rc =3D get_vaddr_frames(start, npages, FOLL_FORCE | FOLL_WRITE,
> > -                               userptr->vec);
> > +       rc =3D pin_user_pages_fast(start, npages, FOLL_FORCE | FOLL_WRI=
TE,
> > +                                userptr->pages);
> >
> >         if (rc !=3D npages) {
> >                 dev_err(hdev->dev,
> >                         "Failed to map host memory, user ptr probably w=
rong\n");
> >                 if (rc < 0)
> > -                       goto destroy_framevec;
> > +                       goto destroy_pages;
> > +               npages =3D rc;
> >                 rc =3D -EFAULT;
> > -               goto put_framevec;
> > -       }
> > -
> > -       if (frame_vector_to_pages(userptr->vec) < 0) {
> > -               dev_err(hdev->dev,
> > -                       "Failed to translate frame vector to pages\n");
> > -               rc =3D -EFAULT;
> > -               goto put_framevec;
> > +               goto put_pages;
> >         }
> > +       userptr->npages =3D npages;
> >
> >         rc =3D sg_alloc_table_from_pages(userptr->sgt,
> > -                                       frame_vector_pages(userptr->vec=
),
> > -                                       npages, offset, size, GFP_ATOMI=
C);
> > +                                      userptr->pages,
> > +                                      npages, offset, size, GFP_ATOMIC=
);
> I think that because the call to kvmalloc_array() is done with
> GFP_KERNEL, there is no point in using GFP_ATOMIC here.
> And actually, this path only needs to avoid yielding when using a
> special debug mode.
> So I suggest putting here GFP_KERNEL.

Huh, I didn't even notice the GFP_ATOMIC here. This looks indeed
strange and GFP_KERNEL should be perfectly fine in a function that
also calls pin_user_pages (since that one can allocate and do worse
stuff like userspace pagefaults).

But since that GFP_ATOMIC is there already I'll do that in a separate patch=
.

> In the meanwhile, I'll run this patch (coupled with the next patch) in
> our C/I to make sure there are no regressions.

Excellent. I'll wait with v3 until that's done, just in case you hit a
snag I need to fix.

Cheers, Daniel

> Thanks,
> Oded
>
> >         if (rc < 0) {
> >                 dev_err(hdev->dev, "failed to create SG table from page=
s\n");
> > -               goto put_framevec;
> > +               goto put_pages;
> >         }
> >
> >         return 0;
> >
> > -put_framevec:
> > -       put_vaddr_frames(userptr->vec);
> > -destroy_framevec:
> > -       frame_vector_destroy(userptr->vec);
> > +put_pages:
> > +       unpin_user_pages(userptr->pages, npages);
> > +destroy_pages:
> > +       kvfree(userptr->pages);
> >         return rc;
> >  }
> >
> > @@ -1405,8 +1401,6 @@ int hl_pin_host_memory(struct hl_device *hdev, u6=
4 addr, u64 size,
> >   */
> >  void hl_unpin_host_memory(struct hl_device *hdev, struct hl_userptr *u=
serptr)
> >  {
> > -       struct page **pages;
> > -
> >         hl_debugfs_remove_userptr(hdev, userptr);
> >
> >         if (userptr->dma_mapped)
> > @@ -1414,15 +1408,8 @@ void hl_unpin_host_memory(struct hl_device *hdev=
, struct hl_userptr *userptr)
> >                                                         userptr->sgt->n=
ents,
> >                                                         userptr->dir);
> >
> > -       pages =3D frame_vector_pages(userptr->vec);
> > -       if (!IS_ERR(pages)) {
> > -               int i;
> > -
> > -               for (i =3D 0; i < frame_vector_count(userptr->vec); i++=
)
> > -                       set_page_dirty_lock(pages[i]);
> > -       }
> > -       put_vaddr_frames(userptr->vec);
> > -       frame_vector_destroy(userptr->vec);
> > +       unpin_user_pages_dirty_lock(userptr->pages, userptr->npages, tr=
ue);
> > +       kvfree(userptr->pages);
> >
> >         list_del(&userptr->job_node);
> >
> > --
> > 2.28.0
> >


--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch