The patch titled
Subject: mm/gup: remove obsolete FOLL_LONGTERM comment
has been added to the -mm mm-unstable branch. Its filename is
mm-gup-remove-obsolete-foll_longterm-comment.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-gup-remove-obsolete-foll_longterm-comment.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Jason Gunthorpe <jgg@xxxxxxxxxx>
Subject: mm/gup: remove obsolete FOLL_LONGTERM comment
Date: Tue, 24 Jan 2023 16:34:23 -0400
These days FOLL_LONGTERM is not allowed at all on any get_user_pages*()
functions, it must be only be used with pin_user_pages*(), plus it now has
universal support for all the pin_user_pages*() functions.
Link: https://lkml.kernel.org/r/2-v2-987e91b59705+36b-gup_tidy_jgg@xxxxxxxxxx
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/include/linux/mm_types.h~mm-gup-remove-obsolete-foll_longterm-comment
+++ a/include/linux/mm_types.h
@@ -1058,12 +1058,6 @@ typedef unsigned int __bitwise zap_flags
* specifically failed. Filesystem pages are still subject to bugs and use of
* FOLL_LONGTERM should be avoided on those pages.
*
- * FIXME: Also NOTE that FOLL_LONGTERM is not supported in every GUP call.
- * Currently only get_user_pages() and get_user_pages_fast() support this flag
- * and calls to get_user_pages_[un]locked are specifically not allowed. This
- * is due to an incompatibility with the FS DAX check and
- * FAULT_FLAG_ALLOW_RETRY.
- *
* In the CMA case: long term pins in a CMA region would unnecessarily fragment
* that region. And so, CMA attempts to migrate the page before pinning, when
* FOLL_LONGTERM is specified.
_
Patches currently in -mm which might be from jgg@xxxxxxxxxx are
mm-gup-have-internal-functions-get-the-mmap_read_lock.patch
mm-gup-remove-obsolete-foll_longterm-comment.patch
mm-gup-dont-call-__gup_longterm_locked-if-foll_longterm-cannot-be-set.patch
mm-gup-move-try_grab_page-to-mm-internalh.patch
mm-gup-simplify-the-external-interface-functions-and-consolidate-invariants.patch
mm-gup-add-an-assertion-that-the-mmap-lock-is-locked.patch
mm-gup-remove-locked-being-null-from-faultin_vma_page_range.patch
mm-gup-add-foll_unlockable.patch
mm-gup-make-locked-never-null-in-the-internal-gup-functions.patch
mm-gup-remove-pin_user_pages_fast_only.patch
mm-gup-make-get_user_pages_fast_only-return-the-common-return-value.patch
mm-gup-move-gup_must_unshare-to-mm-internalh.patch
mm-gup-move-private-gup-foll_-flags-to-internalh.patch
