Per the checklist in RELEASE_CHANGES for the creation of a new stable
branch, this commit does the following things:
- Arm gen_node_support.pl's nodetag ABI stability, based on the contents
of nodetags.h.
- Update URLs of top-level README and Makefile to point to the new
stable version.

Commit 1546e17 accidentally misspelled additionally as
additionaly.  Backpatch to v17 to match where the original
commit was backpatched.

Author: Daniel Gustafsson <daniel@yesql.se>
Backpatch-through: 17

Reported-by: Antonin Houska <ah@cybertec.at>
Author: Antonin Houska <ah@cybertec.at>
Discussion: https://postgr.es/m/5250.1751266701@localhost
Backpatch-through: 18, where da72269 introduced this

Commit 19d8e23 added enum values with the prefix TU_, but a few
comments still referred to TUUI_, which was used in development
versions of the patches committed as 19d8e23.

Author: Yugo Nagata <nagata@sraoss.co.jp>
Discussion: https://postgr.es/m/20250701110216.8ac8a9e4c6f607f1d954f44a@sraoss.co.jp
Backpatch-through: 16

There's a kernel bug in do_pages_stat(), affecting systems combining
64-bit kernel and 32-bit user space. The function splits the request
into chunks of 16 pointers, but forgets the pointers are 32-bit when
advancing to the next chunk. Some of the pointers get skipped, and
memory after the array is interpreted as pointers. The result is that
the produced status of memory pages is mostly bogus.

Systems combining 64-bit and 32-bit environments like this might seem
rare, but that's not the case - all 32-bit Debian packages are built in
a 32-bit chroot on a system with a 64-bit kernel.

This is a long-standing kernel bug (since 2010), affecting pretty much
all kernels, so it'll take time until all systems get a fixed kernel.
Luckily, we can work around the issue by chunking the requests the same
way do_pages_stat() does, at least on affected systems. We don't know
what kernel a 32-bit build will run on, so all 32-bit builds use chunks
of 16 elements (the largest chunk before hitting the issue).

64-bit builds are not affected by this issue, and so could work without
the chunking. But chunking has other advantages, so we apply chunking
even for 64-bit builds, with chunks of 1024 elements.

Reported-by: Christoph Berg <myon@debian.org>
Author: Christoph Berg <myon@debian.org>
Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/aEtDozLmtZddARdB@msg.df7cb.de
Context: https://marc.info/?l=linux-mm&m=175077821909222&w=2
Backpatch-through: 18

When querying NUMA status of pages in shared memory, we need to touch
the memory first to get valid results. This may trigger valgrind
reports, because some of the memory (e.g. unpinned buffers) may be
marked as noaccess.

Solved by adding a valgrind suppresion. An alternative would be to
adjust the access/noaccess status before touching the memory, but that
seems far too invasive. It would require all those places to have
detailed knowledge of what the shared memory stores.

The pg_numa_touch_mem_if_required() macro is replaced with a function.
Macros are invisible to suppressions, so it'd have to suppress reports
for the caller - e.g. pg_get_shmem_allocations_numa(). So we'd suppress
reports for the whole function, and that seems to heavy-handed. It might
easily hide other valid issues.

Reviewed-by: Christoph Berg <myon@debian.org>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/aEtDozLmtZddARdB@msg.df7cb.de
Backpatch-through: 18

Querying the NUMA status can be quite time consuming, especially with
large shared buffers. 8cc139b called numa_move_pages() once, for
all buffers, and we had to wait for the syscall to complete.

But with the chunking, introduced by 7fe2f67 to work around a kernel
bug, we can do CHECK_FOR_INTERRUPTS() after each chunk, allowing users
to abort the execution.

Reviewed-by: Christoph Berg <myon@debian.org>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/aEtDozLmtZddARdB@msg.df7cb.de
Backpatch-through: 18

Broken by commits 7fe2f67, 81f287d and bf1119d. Backpatch
to 18, same as the offending commits.

Backpatch-through: 18

The existing code assumed that O_RDONLY is defined as 0, but this is
not required by POSIX and is not true on GNU Hurd.  We can avoid
the assumption by relying on O_ACCMODE to mask the fcntl() result.
(Hopefully, all supported platforms define that.)

Author: Michael Banck <mbanck@gmx.net>
Co-authored-by: Samuel Thibault
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/6862e8d1.050a0220.194b8d.76fa@mx.google.com
Discussion: https://postgr.es/m/68480868.5d0a0220.1e214d.68a6@mx.google.com
Backpatch-through: 13

We stopped defining IOV_MAX on non-Windows systems in 75357ab, on
the assumption that every non-Windows system defines it in <limits.h>
as required by X/Open.  GNU Hurd, however, doesn't follow that
standard either.  Put back the old logic to assume 16 if it's
not defined.

Author: Michael Banck <mbanck@gmx.net>
Co-authored-by: Christoph Berg <myon@debian.org>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/6862e8d1.050a0220.194b8d.76fa@mx.google.com
Discussion: https://postgr.es/m/6846e0c3.df0a0220.39ef9b.c60e@mx.google.com
Backpatch-through: 16

Commit 7841623 removed the ii_OpclassOptions field, but the
comment was not updated.

Author: Japin Li <japinli@hotmail.com>
Reviewed-by: Richard Guo <guofenglinux@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/ME0P300MB04453E6C7EA635F0ECF41BFCB6832%40ME0P300MB0445.AUSP300.PROD.OUTLOOK.COM

Commit fc0438b added the ii_WithoutOverlaps field, but the comment
was not updated.

Author: Japin Li <japinli@hotmail.com>
Reviewed-by: Richard Guo <guofenglinux@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/ME0P300MB04453E6C7EA635F0ECF41BFCB6832%40ME0P300MB0445.AUSP300.PROD.OUTLOOK.COM

Oversight in commit 0ac5ad5.

Author: Sami Imseih <samimseih@gmail.com>
Co-authored-by: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Discussion: https://postgr.es/m/20150619215231.GT133018%40postgresql.org
Discussion: https://postgr.es/m/CAA5RZ0sjQDDwJfMRb%3DZ13nDLuRpF13ME2L_BdGxi0op8RKjmDg%40mail.gmail.com
Backpatch-through: 13

Commit 7a7b3e1 added the ii_NullsNotDistinct field, but the
comment was not updated.

Author: Japin Li <japinli@hotmail.com>
Reviewed-by: Richard Guo <guofenglinux@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/ME0P300MB04453E6C7EA635F0ECF41BFCB6832%40ME0P300MB0445.AUSP300.PROD.OUTLOOK.COM