2019-11-03 21:19:49

by John Hubbard

Subject: [PATCH v2 09/18] drm/via: set FOLL_PIN via pin_user_pages_fast()

Convert drm/via to use the new pin_user_pages_fast() call, which sets
FOLL_PIN. Setting FOLL_PIN is now required for code that requires
tracking of pinned pages, and therefore for any code that calls
put_user_page().

Reviewed-by: Ira Weiny <[email protected]>
Signed-off-by: John Hubbard <[email protected]>
---
drivers/gpu/drm/via/via_dmablit.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/via/via_dmablit.c b/drivers/gpu/drm/via/via_dmablit.c
index 3db000aacd26..37c5e572993a 100644
--- a/drivers/gpu/drm/via/via_dmablit.c
+++ b/drivers/gpu/drm/via/via_dmablit.c
@@ -239,7 +239,7 @@ via_lock_all_dma_pages(drm_via_sg_info_t *vsg, drm_via_dmablit_t *xfer)
vsg->pages = vzalloc(array_size(sizeof(struct page *), vsg->num_pages));
if (NULL == vsg->pages)
return -ENOMEM;
- ret = get_user_pages_fast((unsigned long)xfer->mem_addr,
+ ret = pin_user_pages_fast((unsigned long)xfer->mem_addr,
vsg->num_pages,
vsg->direction == DMA_FROM_DEVICE ? FOLL_WRITE : 0,
vsg->pages);
--
2.23.0

2019-11-04 17:46:17

by Jerome Glisse

Subject: Re: [PATCH v2 09/18] drm/via: set FOLL_PIN via pin_user_pages_fast()

On Sun, Nov 03, 2019 at 01:18:04PM -0800, John Hubbard wrote:
> Convert drm/via to use the new pin_user_pages_fast() call, which sets
> FOLL_PIN. Setting FOLL_PIN is now required for code that requires
> tracking of pinned pages, and therefore for any code that calls
> put_user_page().
>
> Reviewed-by: Ira Weiny <[email protected]>
> Signed-off-by: John Hubbard <[email protected]>

Please be more explicit that via_dmablit.c is already using put_user_page()
as i am expecting that any conversion to pin_user_pages*() must be pair with
a put_user_page(). I find above commit message bit unclear from that POV.

Reviewed-by: J?r?me Glisse <[email protected]>


> ---
> drivers/gpu/drm/via/via_dmablit.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/via/via_dmablit.c b/drivers/gpu/drm/via/via_dmablit.c
> index 3db000aacd26..37c5e572993a 100644
> --- a/drivers/gpu/drm/via/via_dmablit.c
> +++ b/drivers/gpu/drm/via/via_dmablit.c
> @@ -239,7 +239,7 @@ via_lock_all_dma_pages(drm_via_sg_info_t *vsg, drm_via_dmablit_t *xfer)
> vsg->pages = vzalloc(array_size(sizeof(struct page *), vsg->num_pages));
> if (NULL == vsg->pages)
> return -ENOMEM;
> - ret = get_user_pages_fast((unsigned long)xfer->mem_addr,
> + ret = pin_user_pages_fast((unsigned long)xfer->mem_addr,
> vsg->num_pages,
> vsg->direction == DMA_FROM_DEVICE ? FOLL_WRITE : 0,
> vsg->pages);
> --
> 2.23.0
>

2019-11-04 18:25:41

by John Hubbard

Subject: Re: [PATCH v2 09/18] drm/via: set FOLL_PIN via pin_user_pages_fast()

On 11/4/19 9:44 AM, Jerome Glisse wrote:
> On Sun, Nov 03, 2019 at 01:18:04PM -0800, John Hubbard wrote:
>> Convert drm/via to use the new pin_user_pages_fast() call, which sets
>> FOLL_PIN. Setting FOLL_PIN is now required for code that requires
>> tracking of pinned pages, and therefore for any code that calls
>> put_user_page().
>>
>> Reviewed-by: Ira Weiny <[email protected]>
>> Signed-off-by: John Hubbard <[email protected]>
>
> Please be more explicit that via_dmablit.c is already using put_user_page()
> as i am expecting that any conversion to pin_user_pages*() must be pair with
> a put_user_page(). I find above commit message bit unclear from that POV.
>

OK. This one, and the fs/io_uring (patch 9) and net/xdp (patch 10) were all
cases that had put_user_page() pre-existing. I will add something like the
following to each commit description, for v3:

In partial anticipation of this work, the drm/via driver was already
calling put_user_page() instead of put_page(). Therefore, in order to
convert from the get_user_pages()/put_page() model, to the
pin_user_pages()/put_user_page() model, the only change required
is to change get_user_pages() to pin_user_pages().

thanks,

John Hubbard
NVIDIA

> Reviewed-by: J?r?me Glisse <[email protected]>
>
>
>> ---
>> drivers/gpu/drm/via/via_dmablit.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/via/via_dmablit.c b/drivers/gpu/drm/via/via_dmablit.c
>> index 3db000aacd26..37c5e572993a 100644
>> --- a/drivers/gpu/drm/via/via_dmablit.c
>> +++ b/drivers/gpu/drm/via/via_dmablit.c
>> @@ -239,7 +239,7 @@ via_lock_all_dma_pages(drm_via_sg_info_t *vsg, drm_via_dmablit_t *xfer)
>> vsg->pages = vzalloc(array_size(sizeof(struct page *), vsg->num_pages));
>> if (NULL == vsg->pages)
>> return -ENOMEM;
>> - ret = get_user_pages_fast((unsigned long)xfer->mem_addr,
>> + ret = pin_user_pages_fast((unsigned long)xfer->mem_addr,
>> vsg->num_pages,
>> vsg->direction == DMA_FROM_DEVICE ? FOLL_WRITE : 0,
>> vsg->pages);
>> --
>> 2.23.0
>>
>
>