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Pasha Tatashin a2fff99f92 kho: increase metadata bitmap size to PAGE_SIZE
KHO memory preservation metadata is preserved in 512 byte chunks which
requires their allocation from slab allocator.  Slabs are not safe to be
used with KHO because of kfence, and because partial slabs may lead leaks
to the next kernel.  Change the size to be PAGE_SIZE.

The kfence specifically may cause memory corruption, where it randomly
provides slab objects that can be within the scratch area.  The reason for
that is that kfence allocates its objects prior to KHO scratch is marked
as CMA region.

While this change could potentially increase metadata overhead on systems
with sparsely preserved memory, this is being mitigated by ongoing work to
reduce sparseness during preservation via 1G guest pages.  Furthermore,
this change aligns with future work on a stateless KHO, which will also
use page-sized bitmaps for its radix tree metadata.

Link: https://lkml.kernel.org/r/20251021000852.2924827-3-pasha.tatashin@soleen.com
Fixes: fc33e4b44b ("kexec: enable KHO support for memory preservation")
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-09 21:19:41 -08:00
arch Miscellaneous fixes: 2025-11-08 09:01:11 -08:00
block block-6.18-20251031 2025-10-31 12:57:19 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push contains the following changes: 2025-10-10 08:56:16 -07:00
Documentation gpio fixes for v6.18-rc5 2025-11-07 08:10:55 -08:00
drivers i2c-for-6.18-rc5 2025-11-09 09:29:44 -08:00
fs three smb client fixes 2025-11-08 10:17:30 -08:00
include mm/huge_memory: do not change split_huge_page*() target order silently 2025-11-09 21:19:41 -08:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring: fix regbuf vector size truncation 2025-11-07 17:17:13 -07:00
ipc namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
kernel kho: increase metadata bitmap size to PAGE_SIZE 2025-11-09 21:19:41 -08:00
lib Crypto library fixes for v6.18-rc5 2025-11-06 12:48:18 -08:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm/huge_memory: do not change split_huge_page*() target order silently 2025-11-09 21:19:41 -08:00
net Including fixes from bluetooth and wireless. 2025-11-06 08:52:30 -08:00
rust rust: kbuild: workaround rustdoc doctests modifier bug 2025-11-04 00:00:06 +01:00
samples Char/Misc/IIO/Binder changes for 6.18-rc1 2025-10-04 16:26:32 -07:00
scripts kbuild: Let kernel-doc.py use PYTHON3 override 2025-11-08 19:42:22 -07:00
security integrity-v6.18 2025-10-05 10:48:33 -07:00
sound ASoC: Fixes for v6.18 2025-10-30 13:08:08 +01:00
tools iommufd 6.18 first rc pull 2025-11-07 13:13:09 -08:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM x86 fixes for 6.18: 2025-10-18 10:25:43 +02:00
.clang-format memblock: drop for_each_free_mem_pfn_range_in_zone_from() 2025-09-14 08:49:03 +03:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap linux_kselftest-kunit-fixes-6.18-rc4 2025-10-30 19:11:27 -07:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS perf tools fixes for v6.18: 2025-11-06 16:05:33 -08:00
Makefile Linux 6.18-rc5 2025-11-09 15:10:19 -08:00
README README: Fix spelling 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.