[PATCH 1/5] drm: Remove PageReserved manipulation from drm_pci_alloc

[Alex Deucher]

On Sun, Feb 2, 2020 at 12:16 PM Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> drm_pci_alloc/drm_pci_free are very thin wrappers around the core dma
> facilities, and we have no special reason within the drm layer to behave
> differently. In particular, since
>
> commit de09d31dd38a50fdce106c15abd68432eebbd014
> Author: Kirill A. Shutemov <kirill.shutemov at linux.intel.com>
> Date:   Fri Jan 15 16:51:42 2016 -0800
>
>     page-flags: define PG_reserved behavior on compound pages
>
>     As far as I can see there's no users of PG_reserved on compound pages.
>     Let's use PF_NO_COMPOUND here.
>
> it has been illegal to combine GFP_COMP with SetPageReserved, so lets
> stop doing both and leave the dma layer to its own devices.
>
> Reported-by: Taketo Kabe

Needs an email address.

> Closes: https://gitlab.freedesktop.org/drm/intel/issues/1027

Should be Bug: rather than Closes:

> Fixes: de09d31dd38a ("page-flags: define PG_reserved behavior on compound pages")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: <stable at vger.kernel.org> # v4.5+

With those fixed:
Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/drm_pci.c | 23 ++---------------------
>  1 file changed, 2 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
> index f2e43d341980..d16dac4325f9 100644
> --- a/drivers/gpu/drm/drm_pci.c
> +++ b/drivers/gpu/drm/drm_pci.c
> @@ -51,8 +51,6 @@
>  drm_dma_handle_t *drm_pci_alloc(struct drm_device * dev, size_t size, size_t align)
>  {
>         drm_dma_handle_t *dmah;
> -       unsigned long addr;
> -       size_t sz;
>
>         /* pci_alloc_consistent only guarantees alignment to the smallest
>          * PAGE_SIZE order which is greater than or equal to the requested size.
> @@ -68,20 +66,13 @@ drm_dma_handle_t *drm_pci_alloc(struct drm_device * dev, size_t size, size_t ali
>         dmah->size = size;
>         dmah->vaddr = dma_alloc_coherent(&dev->pdev->dev, size,
>                                          &dmah->busaddr,
> -                                        GFP_KERNEL | __GFP_COMP);
> +                                        GFP_KERNEL);
>
>         if (dmah->vaddr == NULL) {
>                 kfree(dmah);
>                 return NULL;
>         }
>
> -       /* XXX - Is virt_to_page() legal for consistent mem? */
> -       /* Reserve */
> -       for (addr = (unsigned long)dmah->vaddr, sz = size;
> -            sz > 0; addr += PAGE_SIZE, sz -= PAGE_SIZE) {
> -               SetPageReserved(virt_to_page((void *)addr));
> -       }
> -
>         return dmah;
>  }
>
> @@ -94,19 +85,9 @@ EXPORT_SYMBOL(drm_pci_alloc);
>   */
>  void __drm_legacy_pci_free(struct drm_device * dev, drm_dma_handle_t * dmah)
>  {
> -       unsigned long addr;
> -       size_t sz;
> -
> -       if (dmah->vaddr) {
> -               /* XXX - Is virt_to_page() legal for consistent mem? */
> -               /* Unreserve */
> -               for (addr = (unsigned long)dmah->vaddr, sz = dmah->size;
> -                    sz > 0; addr += PAGE_SIZE, sz -= PAGE_SIZE) {
> -                       ClearPageReserved(virt_to_page((void *)addr));
> -               }
> +       if (dmah->vaddr)
>                 dma_free_coherent(&dev->pdev->dev, dmah->size, dmah->vaddr,
>                                   dmah->busaddr);
> -       }
>  }
>
>  /**
> --
> 2.25.0
>
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