* [PATCH v2] mm: gup: fix comment of __get_user_pages()
@ 2019-10-24 15:04 Liu Xiang
2019-10-24 16:10 ` David Hildenbrand
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Liu Xiang @ 2019-10-24 15:04 UTC (permalink / raw)
To: linux-mm; +Cc: linux-kernel, jhubbard, liuxiang_1999
Fix comment of __get_user_pages() and make it more clear.
Suggested-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Liu Xiang <liuxiang_1999@126.com>
---
Changes in v2:
as suggested by John, rewrite the comment about return value.
mm/gup.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 8f236a3..bc6a254 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -734,11 +734,17 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
* Or NULL if the caller does not require them.
* @nonblocking: whether waiting for disk IO or mmap_sem contention
*
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno. Each page returned must be released
- * with a put_page() call when it is finished with. vmas will only
- * remain valid while mmap_sem is held.
+ * Returns either number of pages pinned (which may be less than the
+ * number requested), or an error. Details about the return value:
+ *
+ * -- If nr_pages is 0, returns 0.
+ * -- If nr_pages is >0, but no pages were pinned, returns -errno.
+ * -- If nr_pages is >0, and some pages were pinned, returns the number of
+ * pages pinned. Again, this may be less than nr_pages.
+ *
+ * The caller is responsible for releasing returned @pages, via put_page().
+ *
+ * @vmas are valid only as long as mmap_sem is held.
*
* Must be called with mmap_sem held. It may be released. See below.
*
--
1.9.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] mm: gup: fix comment of __get_user_pages()
2019-10-24 15:04 [PATCH v2] mm: gup: fix comment of __get_user_pages() Liu Xiang
@ 2019-10-24 16:10 ` David Hildenbrand
2019-10-24 17:40 ` John Hubbard
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: David Hildenbrand @ 2019-10-24 16:10 UTC (permalink / raw)
To: Liu Xiang, linux-mm; +Cc: linux-kernel, jhubbard
On 24.10.19 17:04, Liu Xiang wrote:
> Fix comment of __get_user_pages() and make it more clear.
>
> Suggested-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Liu Xiang <liuxiang_1999@126.com>
> ---
>
> Changes in v2:
> as suggested by John, rewrite the comment about return value.
>
> mm/gup.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/mm/gup.c b/mm/gup.c
> index 8f236a3..bc6a254 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -734,11 +734,17 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
> * Or NULL if the caller does not require them.
> * @nonblocking: whether waiting for disk IO or mmap_sem contention
> *
> - * Returns number of pages pinned. This may be fewer than the number
> - * requested. If nr_pages is 0 or negative, returns 0. If no pages
> - * were pinned, returns -errno. Each page returned must be released
> - * with a put_page() call when it is finished with. vmas will only
> - * remain valid while mmap_sem is held.
> + * Returns either number of pages pinned (which may be less than the
> + * number requested), or an error. Details about the return value:
> + *
> + * -- If nr_pages is 0, returns 0.
> + * -- If nr_pages is >0, but no pages were pinned, returns -errno.
> + * -- If nr_pages is >0, and some pages were pinned, returns the number of
> + * pages pinned. Again, this may be less than nr_pages.
> + *
> + * The caller is responsible for releasing returned @pages, via put_page().
> + *
> + * @vmas are valid only as long as mmap_sem is held.
> *
> * Must be called with mmap_sem held. It may be released. See below.
> *
>
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] mm: gup: fix comment of __get_user_pages()
2019-10-24 15:04 [PATCH v2] mm: gup: fix comment of __get_user_pages() Liu Xiang
2019-10-24 16:10 ` David Hildenbrand
@ 2019-10-24 17:40 ` John Hubbard
2019-10-24 18:41 ` David Rientjes
2019-10-28 18:50 ` John Hubbard
3 siblings, 0 replies; 5+ messages in thread
From: John Hubbard @ 2019-10-24 17:40 UTC (permalink / raw)
To: Liu Xiang, linux-mm; +Cc: linux-kernel
On 10/24/19 8:04 AM, Liu Xiang wrote:
> Fix comment of __get_user_pages() and make it more clear.
>
> Suggested-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Liu Xiang <liuxiang_1999@126.com>
> ---
>
> Changes in v2:
> as suggested by John, rewrite the comment about return value.
>
> mm/gup.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
thanks,
--
John Hubbard
NVIDIA
> diff --git a/mm/gup.c b/mm/gup.c
> index 8f236a3..bc6a254 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -734,11 +734,17 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
> * Or NULL if the caller does not require them.
> * @nonblocking: whether waiting for disk IO or mmap_sem contention
> *
> - * Returns number of pages pinned. This may be fewer than the number
> - * requested. If nr_pages is 0 or negative, returns 0. If no pages
> - * were pinned, returns -errno. Each page returned must be released
> - * with a put_page() call when it is finished with. vmas will only
> - * remain valid while mmap_sem is held.
> + * Returns either number of pages pinned (which may be less than the
> + * number requested), or an error. Details about the return value:
> + *
> + * -- If nr_pages is 0, returns 0.
> + * -- If nr_pages is >0, but no pages were pinned, returns -errno.
> + * -- If nr_pages is >0, and some pages were pinned, returns the number of
> + * pages pinned. Again, this may be less than nr_pages.
> + *
> + * The caller is responsible for releasing returned @pages, via put_page().
> + *
> + * @vmas are valid only as long as mmap_sem is held.
> *
> * Must be called with mmap_sem held. It may be released. See below.
> *
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] mm: gup: fix comment of __get_user_pages()
2019-10-24 15:04 [PATCH v2] mm: gup: fix comment of __get_user_pages() Liu Xiang
2019-10-24 16:10 ` David Hildenbrand
2019-10-24 17:40 ` John Hubbard
@ 2019-10-24 18:41 ` David Rientjes
2019-10-28 18:50 ` John Hubbard
3 siblings, 0 replies; 5+ messages in thread
From: David Rientjes @ 2019-10-24 18:41 UTC (permalink / raw)
To: Liu Xiang; +Cc: linux-mm, linux-kernel, jhubbard
On Thu, 24 Oct 2019, Liu Xiang wrote:
> Fix comment of __get_user_pages() and make it more clear.
>
> Suggested-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Liu Xiang <liuxiang_1999@126.com>
Acked-by: David Rientjes <rientjes@google.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] mm: gup: fix comment of __get_user_pages()
2019-10-24 15:04 [PATCH v2] mm: gup: fix comment of __get_user_pages() Liu Xiang
` (2 preceding siblings ...)
2019-10-24 18:41 ` David Rientjes
@ 2019-10-28 18:50 ` John Hubbard
3 siblings, 0 replies; 5+ messages in thread
From: John Hubbard @ 2019-10-28 18:50 UTC (permalink / raw)
To: Liu Xiang, linux-mm; +Cc: linux-kernel
On 10/24/19 8:04 AM, Liu Xiang wrote:
> Fix comment of __get_user_pages() and make it more clear.
>
> Suggested-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Liu Xiang <liuxiang_1999@126.com>
> ---
>
> Changes in v2:
> as suggested by John, rewrite the comment about return value.
>
> mm/gup.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/mm/gup.c b/mm/gup.c
> index 8f236a3..bc6a254 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -734,11 +734,17 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
> * Or NULL if the caller does not require them.
> * @nonblocking: whether waiting for disk IO or mmap_sem contention
> *
> - * Returns number of pages pinned. This may be fewer than the number
> - * requested. If nr_pages is 0 or negative, returns 0. If no pages
> - * were pinned, returns -errno. Each page returned must be released
> - * with a put_page() call when it is finished with. vmas will only
> - * remain valid while mmap_sem is held.
> + * Returns either number of pages pinned (which may be less than the
> + * number requested), or an error. Details about the return value:
> + *
> + * -- If nr_pages is 0, returns 0.
> + * -- If nr_pages is >0, but no pages were pinned, returns -errno.
> + * -- If nr_pages is >0, and some pages were pinned, returns the number of
> + * pages pinned. Again, this may be less than nr_pages.
> + *
> + * The caller is responsible for releasing returned @pages, via put_page().
> + *
> + * @vmas are valid only as long as mmap_sem is held.
Just remembered: this identical paragraph is also written in the
get_user_pages_remote() comments. It would be ideal to apply the same fix to
that identical blob of text.
thanks,
--
John Hubbard
NVIDIA
> *
> * Must be called with mmap_sem held. It may be released. See below.
> *
>
^ permalink raw reply [flat|nested] 5+ messages in thread
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2019-10-24 15:04 [PATCH v2] mm: gup: fix comment of __get_user_pages() Liu Xiang
2019-10-24 16:10 ` David Hildenbrand
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2019-10-24 18:41 ` David Rientjes
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