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aa39ca6940
We want to get rid of follow_page(), and have a more reasonable way to just lookup a folio mapped at a certain address, perform some checks while still under PTL, and then only conditionally grab a folio reference if really required. Further, we might want to get rid of some walk_page_range*() users that really only want to temporarily lookup a single folio at a single address. So let's add a new page table walker that does exactly that, similarly to GUP also being able to walk hugetlb VMAs. Add folio_walk_end() as a macro for now: the compiler is not easy to please with the pte_unmap()->kunmap_local(). Note that one difference between follow_page() and get_user_pages(1) is that follow_page() will not trigger faults to get something mapped. So folio_walk is at least currently not a replacement for get_user_pages(1), but could likely be extended/reused to achieve something similar in the future. Link: https://lkml.kernel.org/r/20240802155524.517137-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Janosch Frank <frankja@linux.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.