From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: + mm-gup-documentation-fix-for-pin_user_pages-apis.patch added to -mm tree Date: Fri, 29 May 2020 13:08:43 -0700 Message-ID: <20200529200843.aGMW1M-PS%akpm@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:45124 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726866AbgE2UIq (ORCPT ); Fri, 29 May 2020 16:08:46 -0400 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: dan.carpenter@oracle.com, david@redhat.com, jack@suse.cz, jhubbard@nvidia.com, mm-commits@vger.kernel.org, vbabka@suse.cz The patch titled Subject: mm/gup: documentation fix for pin_user_pages*() APIs has been added to the -mm tree. Its filename is mm-gup-documentation-fix-for-pin_user_pages-apis.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-gup-documentation-fix-for-pin_user_pages-apis.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-gup-documentation-fix-for-pin_user_pages-apis.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: John Hubbard 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/20200529084515.46259-1-jhubbard@nvidia.com Signed-off-by: John Hubbard Reviewed-by: David Hildenbrand Cc: Dan Carpenter Cc: Jan Kara Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/gup.c | 9 --------- 1 file changed, 9 deletions(-) --- a/mm/gup.c~mm-gup-documentation-fix-for-pin_user_pages-apis +++ a/mm/gup.c @@ -2876,9 +2876,6 @@ 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) @@ -2952,9 +2949,6 @@ 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, @@ -2988,9 +2982,6 @@ 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, _ Patches currently in -mm which might be from jhubbard@nvidia.com are mm-gup-introduce-pin_user_pages_unlocked.patch ivtv-convert-get_user_pages-pin_user_pages.patch mm-gup-move-__get_user_pages_fast-down-a-few-lines-in-gupc.patch mm-gup-refactor-and-de-duplicate-gup_fast-code.patch mm-gup-refactor-and-de-duplicate-gup_fast-code-fix.patch mm-gup-introduce-pin_user_pages_fast_only.patch drm-i915-convert-get_user_pages-pin_user_pages.patch mm-gup-might_lock_readmmap_sem-in-get_user_pages_fast.patch khugepaged-add-self-test-fix-3.patch rapidio-convert-get_user_pages-pin_user_pages.patch mm-gup-update-pin_user_pagesrst-for-case-3-mmu-notifiers.patch mm-gup-introduce-pin_user_pages_locked.patch mm-gup-frame_vector-convert-get_user_pages-pin_user_pages.patch mm-gup-documentation-fix-for-pin_user_pages-apis.patch