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[ Upstream commit 2c1f057e5be63e890f2dd89e4c25ab5eef084a91 ] We added PM_MMAP_EXCLUSIVE in 2015 via commit77bb499bb6("pagemap: add mmap-exclusive bit for marking pages mapped only here"), when THPs could not be partially mapped and page_mapcount() returned something that was true for all pages of the THP. In 2016, we added support for partially mapping THPs via commit53f9263bab("mm: rework mapcount accounting to enable 4k mapping of THPs") but missed to determine PM_MMAP_EXCLUSIVE as well per page. Checking page_mapcount() on the head page does not tell the whole story. We should check each individual page. In a future without per-page mapcounts it will be different, but we'll change that to be consistent with PTE-mapped THPs once we deal with that. Link: https://lkml.kernel.org/r/20240607122357.115423-4-david@redhat.com Fixes:53f9263bab("mm: rework mapcount accounting to enable 4k mapping of THPs") Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Lance Yang <ioworker0@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.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 Restructured Text 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.