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mm-gup-documentation-fix-for-pin_user_pages-apis.patch removed from -mm tree

merged [email protected] 1 participant 1 message Jun 8, 2020

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The patch titled
Subject: mm/gup: documentation fix for pin_user_pages*() APIs
has been removed from the -mm tree. Its filename was
mm-gup-documentation-fix-for-pin_user_pages-apis.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: John Hubbard <[email protected]>
Subject: mm/gup: documentation fix for pin_user_pages*() APIs

All of the pin_user_pages*() API calls will cause pages to be dma-pinned. As such, they are all suitable for either DMA, RDMA, and/or Direct IO. The documentation should say so, but it was instead saying that three of the API calls were only suitable for Direct IO. This was discovered when a reviewer wondered why an API call that specifically recommended against Case 2 (DMA/RDMA) was being used in a DMA situation [1].

Fix this by simply deleting those claims. The gup.c comments already refer to the more extensive Documentation/core-api/pin_user_pages.rst, which does have the correct guidance. So let's just write it once, there.

[1] https://lore.kernel.org/r/20200529074658.GM30374@kadam

Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by John Hubbard <[email protected]>
Reviewed-by David Hildenbrand <[email protected]>
Acked-by Pankaj Gupta <[email protected]>
Acked-by Souptick Joarder <[email protected]>
Cc Dan Carpenter <[email protected]>
Cc Jan Kara <[email protected]>
Cc Vlastimil Babka <[email protected]>
Signed-off-by Andrew Morton <[email protected]>

---

 mm/gup.c |    9 ---------
 1 file changed, 9 deletions(-)
mm/gup.c renamed from mm/gup.c~mm-gup-documentation-fix-for-pin_user_pages-apis +0 -9
@@ -2918,9 +2918,6 @@ EXPORT_SYMBOL_GPL(get_user_pages_fast);
  *
  * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
  * see Documentation/core-api/pin_user_pages.rst for further details.
- *
- * This is intended for Case 1 (DIO) in Documentation/core-api/pin_user_pages.rst. It
- * is NOT intended for Case 2 (RDMA: long-term pins).
  */
 int pin_user_pages_fast(unsigned long start, int nr_pages,
 			unsigned int gup_flags, struct page **pages)

@@ -2994,9 +2991,6 @@ EXPORT_SYMBOL_GPL(pin_user_pages_fast_on
  *
  * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
  * see Documentation/core-api/pin_user_pages.rst for details.
- *
- * This is intended for Case 1 (DIO) in Documentation/core-api/pin_user_pages.rst. It
- * is NOT intended for Case 2 (RDMA: long-term pins).
  */
 long pin_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 			   unsigned long start, unsigned long nr_pages,

@@ -3030,9 +3024,6 @@ EXPORT_SYMBOL(pin_user_pages_remote);
  *
  * FOLL_PIN means that the pages must be released via unpin_user_page(). Please
  * see Documentation/core-api/pin_user_pages.rst for details.
- *
- * This is intended for Case 1 (DIO) in Documentation/core-api/pin_user_pages.rst. It
- * is NOT intended for Case 2 (RDMA: long-term pins).
  */
 long pin_user_pages(unsigned long start, unsigned long nr_pages,
 		    unsigned int gup_flags, struct page **pages,

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