Akinobu Mita c42af83c59 memblock: fix memblock_estimated_nr_free_pages() for soft-reserved memory
memblock_estimated_nr_free_pages() returns the difference between the total
size of the "memory" memblock type and the "reserved" memblock type.

The "soft-reserved" memory regions are added to the "reserved" memblock
type, but not to the "memory" memblock type. Therefore,
memblock_estimated_nr_free_pages() may return a smaller value than
expected, or if it underflows, an extremely large value.

/proc/sys/kernel/threads-max is determined by the value of
memblock_estimated_nr_free_pages().  This issue was discovered on machines
with CXL memory because kernel.threads-max was either smaller than expected
or extremely large for the installed DRAM size.

This fixes the issue by replacing memblock_reserved_size() with
memblock_reserved_kern_size() that tells how much memory was
reserved from the actual RAM.

Suggested-by: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Link: https://patch.msgid.link/20251111010010.7800-1-akinobu.mita@gmail.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
2025-11-11 18:15:35 +02:00
…
2025-02-19 14:53:27 -07:00
2025-11-09 15:10:19 -08:00
2024-03-18 03:36:32 -06:00

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.
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