Re: [PATCH v2] drm/etnaviv: convert get_user_pages() --> pin_user_pages()

[Lucas Stach]

Am Montag, den 25.05.2020, 16:49 -0700 schrieb John Hubbard:
> This code was using get_user_pages*(), in a "Case 2" scenario
> (DMA/RDMA), using the categorization from [1]. That means that it's
> time to convert the get_user_pages*() + put_page() calls to
> pin_user_pages*() + unpin_user_pages() calls.
> 
> There is some helpful background in [2]: basically, this is a small
> part of fixing a long-standing disconnect between pinning pages, and
> file systems' use of those pages.
> 
> [1] Documentation/core-api/pin_user_pages.rst
> 
> [2] "Explicit pinning of user-space pages":
> https://lwn.net/Articles/807108/
> 
> Signed-off-by: John Hubbard 

Thanks, I've applied this to etnaviv/next.

Regards,
Lucas

> ---
> 
> Hi,
> 
> Changes since v1:
> 
> * Rebased onto Linux 5.7-rc7
> 
> * Added: Lucas Stach
> 
> thanks
> John Hubbard
> NVIDIA
> 
> 
>  drivers/gpu/drm/etnaviv/etnaviv_gem.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c 
> b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
> index dc9ef302f517..0f4578dc169d 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
> @@ -675,10 +675,10 @@ static int etnaviv_gem_userptr_get_pages(struct 
> etnaviv_gem_object *etnaviv_obj)
>   uint64_t ptr = userptr->ptr + pinned * PAGE_SIZE;
>   struct page **pages = pvec + pinned;
>  
> - ret = get_user_pages_fast(ptr, num_pages,
> + ret = pin_user_pages_fast(ptr, num_pages,
> !userptr->ro ? FOLL_WRITE : 0, pages);
>   if (ret < 0) {
> - release_pages(pvec, pinned);
> + unpin_user_pages(pvec, pinned);
>   kvfree(pvec);
>   return ret;
>   }
> @@ -702,7 +702,7 @@ static void etnaviv_gem_userptr_release(struct 
> etnaviv_gem_object *etnaviv_obj)
>   if (etnaviv_obj->pages) {
>   int npages = etnaviv_obj->base.size >> PAGE_SHIFT;
>  
> - release_pages(etnaviv_obj->pages, npages);
> + unpin_user_pages(etnaviv_obj->pages, npages);
>   kvfree(etnaviv_obj->pages);
>   }
>  }

[PATCH v2] drm/etnaviv: convert get_user_pages() --> pin_user_pages()

[John Hubbard]

This code was using get_user_pages*(), in a "Case 2" scenario
(DMA/RDMA), using the categorization from [1]. That means that it's
time to convert the get_user_pages*() + put_page() calls to
pin_user_pages*() + unpin_user_pages() calls.

There is some helpful background in [2]: basically, this is a small
part of fixing a long-standing disconnect between pinning pages, and
file systems' use of those pages.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
https://lwn.net/Articles/807108/

Signed-off-by: John Hubbard 
---

Hi,

Changes since v1:

* Rebased onto Linux 5.7-rc7

* Added: Lucas Stach

thanks
John Hubbard
NVIDIA


 drivers/gpu/drm/etnaviv/etnaviv_gem.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c 
b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index dc9ef302f517..0f4578dc169d 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -675,10 +675,10 @@ static int etnaviv_gem_userptr_get_pages(struct 
etnaviv_gem_object *etnaviv_obj)
uint64_t ptr = userptr->ptr + pinned * PAGE_SIZE;
struct page **pages = pvec + pinned;
 
-   ret = get_user_pages_fast(ptr, num_pages,
+   ret = pin_user_pages_fast(ptr, num_pages,
  !userptr->ro ? FOLL_WRITE : 0, pages);
if (ret < 0) {
-   release_pages(pvec, pinned);
+   unpin_user_pages(pvec, pinned);
kvfree(pvec);
return ret;
}
@@ -702,7 +702,7 @@ static void etnaviv_gem_userptr_release(struct 
etnaviv_gem_object *etnaviv_obj)
if (etnaviv_obj->pages) {
int npages = etnaviv_obj->base.size >> PAGE_SHIFT;
 
-   release_pages(etnaviv_obj->pages, npages);
+   unpin_user_pages(etnaviv_obj->pages, npages);
kvfree(etnaviv_obj->pages);
}
 }
-- 
2.26.2