Mike Rapoport (Microsoft) 6bbf0e7285 execmem: enforce allocation size aligment to PAGE_SIZE
Before introduction of ROX cache execmem allocation size was always
implicitly aligned to PAGE_SIZE inside vmalloc.

However, when allocation happens from the ROX cache, this is not
enforced.

Make sure that the allocation size is always consistently aligned to
PAGE_SIZE.

Mike said:

: Right now it'll make the maple trees in execmem_cache more compact. 
: And it's a precaution for the case when execmem callers would want to
: change permissions on unaligned range because that would WARN_ON()
: loudly.

Peter said

: It should not have a runtime effect -- currently all this code is used
: with PAGE_SIZE multiples and everything just works.  But whilst I was
: perusing this code, I noticed that nothing actually enforced this.  If
: someone were to break this assumption things will go sideways.

Link: https://lkml.kernel.org/r/20250423144808.1619863-1-rppt@kernel.org
Fixes: 2e45474ab1 ("execmem: add support for cache of large ROX pages")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-12 23:50:33 -07:00
2024-09-01 20:43:24 -07:00
2025-02-19 14:53:27 -07:00
2025-05-11 14:54:11 -07:00
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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