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[RFC,19/19] habanalabs: remove FOLL_FORCE usage

Message ID 20221107161740.144456-20-david@redhat.com
State New
Headers
Series mm/gup: remove FOLL_FORCE usage from drivers (reliable R/O long-term pinning) |

Commit Message

David Hildenbrand Nov. 7, 2022, 4:17 p.m. UTC 
  FOLL_FORCE is really only for debugger access. As we unpin the pinned pages
using unpin_user_pages_dirty_lock(true), the assumption is that all these
pages are writable.

FOLL_FORCE in this case seems to be due to copy-and-past from other
drivers. Let's just remove it.

Cc: Oded Gabbay <ogabbay@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 drivers/misc/habanalabs/common/memory.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Oded Gabbay Nov. 7, 2022, 9:25 p.m. UTC | #1 
On Mon, Nov 7, 2022 at 6:19 PM David Hildenbrand <david@redhat.com> wrote:
>
> FOLL_FORCE is really only for debugger access. As we unpin the pinned pages
> using unpin_user_pages_dirty_lock(true), the assumption is that all these
> pages are writable.
>
> FOLL_FORCE in this case seems to be due to copy-and-past from other
> drivers. Let's just remove it.
>
> Cc: Oded Gabbay <ogabbay@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  drivers/misc/habanalabs/common/memory.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/misc/habanalabs/common/memory.c b/drivers/misc/habanalabs/common/memory.c
> index ef28f3b37b93..e35cca96bbef 100644
> --- a/drivers/misc/habanalabs/common/memory.c
> +++ b/drivers/misc/habanalabs/common/memory.c
> @@ -2312,8 +2312,7 @@ static int get_user_memory(struct hl_device *hdev, u64 addr, u64 size,
>         if (!userptr->pages)
>                 return -ENOMEM;
>
> -       rc = pin_user_pages_fast(start, npages,
> -                                FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM,
> +       rc = pin_user_pages_fast(start, npages, FOLL_WRITE | FOLL_LONGTERM,
>                                  userptr->pages);
>
>         if (rc != npages) {
> --
> 2.38.1
>
>
Acked-by: Oded Gabbay <ogabbay@kernel.org>
Thanks,
Oded
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Patch

diff --git a/drivers/misc/habanalabs/common/memory.c b/drivers/misc/habanalabs/common/memory.c
index ef28f3b37b93..e35cca96bbef 100644
--- a/drivers/misc/habanalabs/common/memory.c
+++ b/drivers/misc/habanalabs/common/memory.c
@@ -2312,8 +2312,7 @@  static int get_user_memory(struct hl_device *hdev, u64 addr, u64 size,
 	if (!userptr->pages)
 		return -ENOMEM;
 
-	rc = pin_user_pages_fast(start, npages,
-				 FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM,
+	rc = pin_user_pages_fast(start, npages, FOLL_WRITE | FOLL_LONGTERM,
 				 userptr->pages);
 
 	if (rc != npages) {