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ae1b9fb2d5
Rearrange region-third and segment table entry SW bits, in order to
make room for future encoding of region/segment table swap entries.
Also adjust _SEGMENT_ENTRY_GMAP_UC and _SEGMENT_ENTRY_GMAP_IN bits in
gmap code. Those should only apply for gmap PMDs, and not really depend
on or conflict with host PMD bits, but for consistency also adjust them:
- _SEGMENT_ENTRY_GMAP_UC "dirty (migration)" was using the same bit as
_SEGMENT_ENTRY_SOFT_DIRTY in the host PMD -> make it use the new
SOFT_DIRTY bit 63 (0x0002)
- _SEGMENT_ENTRY_GMAP_IN "invalidation notify bit" was using 0x8000,
which was an unused bit in the host PMD, that is now used for
_SEGMENT_ENTRY_WRITE -> make it use bit 52 (0x0800) instead, which is
still unused in the host PMD
This is a prerequisite for hugetlbfs PTE_MARKER support on s390, which
is needed to fix a regression introduced with commit 8a13897fb0
("mm: userfaultfd: support UFFDIO_POISON for hugetlbfs"). That commit
depends on the availability of swap entries for hugetlbfs, which were
not available for s390 so far.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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.