2020-05-25 23:54:05

by John Hubbard

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

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 <[email protected]>
---

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

2020-06-18 18:37:09

by Lucas Stach

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

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 <[email protected]>

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);
> }
> }