a5989d4ed4
Currently free meta can only be stored in object if the object is not
smaller than free meta.
After the improvement, when the object is smaller than free meta and SLUB
DEBUG is not enabled, it is possible to store part of the free meta in the
object, reducing the increased size of the red zone.
Example:
free meta size: 16 bytes
alloc meta size: 16 bytes
object size: 8 bytes
optimal redzone size (object_size <= 64): 16 bytes
Before improvement:
actual redzone size = alloc meta size + free meta size = 32 bytes
After improvement:
actual redzone size = alloc meta size + (free meta size - object size)
= 24 bytes
[juntong.deng@outlook.com: make kasan_metadata_size() adapt to the improved free meta storage]
Link: https://lkml.kernel.org/r/VI1P193MB0752675D6E0A2D16CE656F8299BAA@VI1P193MB0752.EURP193.PROD.OUTLOOK.COM
Link: https://lkml.kernel.org/r/VI1P193MB0752DE2CCD9046B5FED0AA8E99B5A@VI1P193MB0752.EURP193.PROD.OUTLOOK.COM
Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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.