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mm/gup: remove obsolete FOLL_LONGTERM comment

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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@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Jason Gunthorpe 2023-01-24 16:34:23 -04:00 committed by Andrew Morton
parent b2a72dff85
commit 7427c30bea
1 changed files with 0 additions and 6 deletions
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6
include/linux/mm_types.h
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@ -1053,12 +1053,6 @@ typedef unsigned int __bitwise zap_flags_t;
* 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.