Re: [PATCH v2 03/17] misc/habana: Stop using frame_vector helpers

[Oded Gabbay <oded.gabbay@gmail.com>]

On Fri, Oct 9, 2020 at 10:59 AM Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
>
> 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: Jérôme 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 ?

>         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/habanalabs/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 *hdev, u64 addr, u64 size,
>                 return -EFAULT;
>         }
>
> -       userptr->vec = frame_vector_create(npages);
> -       if (!userptr->vec) {
> +       userptr->pages = kvmalloc_array(npages, sizeof(*userptr->pages),
> +                                       GFP_KERNEL);
> +       if (!userptr->pages) {
>                 dev_err(hdev->dev, "Failed to create frame vector\n");
>                 return -ENOMEM;
>         }
>
> -       rc = get_vaddr_frames(start, npages, FOLL_FORCE | FOLL_WRITE,
> -                               userptr->vec);
> +       rc = pin_user_pages_fast(start, npages, FOLL_FORCE | FOLL_WRITE,
> +                                userptr->pages);
>
>         if (rc != npages) {
>                 dev_err(hdev->dev,
>                         "Failed to map host memory, user ptr probably wrong\n");
>                 if (rc < 0)
> -                       goto destroy_framevec;
> +                       goto destroy_pages;
> +               npages = rc;
>                 rc = -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 = -EFAULT;
> -               goto put_framevec;
> +               goto put_pages;
>         }
> +       userptr->npages = npages;
>
>         rc = sg_alloc_table_from_pages(userptr->sgt,
> -                                       frame_vector_pages(userptr->vec),
> -                                       npages, offset, size, GFP_ATOMIC);
> +                                      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.

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

>         if (rc < 0) {
>                 dev_err(hdev->dev, "failed to create SG table from pages\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, u64 addr, u64 size,
>   */
>  void hl_unpin_host_memory(struct hl_device *hdev, struct hl_userptr *userptr)
>  {
> -       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->nents,
>                                                         userptr->dir);
>
> -       pages = frame_vector_pages(userptr->vec);
> -       if (!IS_ERR(pages)) {
> -               int i;
> -
> -               for (i = 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, true);
> +       kvfree(userptr->pages);
>
>         list_del(&userptr->job_node);
>
> --
> 2.28.0
>
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