Performance oriented customized Linux kernel based on the mainline kernel.
3e844d842d
There are a few kernel users like kfence that require 4k pages to work
correctly and do not support large mappings. They use set_memory_4k()
to break down those large mappings.
That, in turn relies on cpa_data->force_split option to indicate to
set_memory code that it should split page tables regardless of whether
the need to be.
But, a recent change added an optimization which would return early
if a set_memory request came in that did not change permissions. It
did not consult ->force_split and would mistakenly optimize away the
splitting that set_memory_4k() needs. This broke kfence.
Skip the same-permission optimization when ->force_split is set.
Fixes: 127960a05548 ("x86/mm: Inhibit _PAGE_NX changes from cpa_process_alias()")
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Marco Elver <elver@google.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/CA+G9fYuFxZTxkeS35VTZMXwQvohu73W3xbZ5NtjebsVvH6hCuA@mail.gmail.com/
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.