Alexander Potapenko
db70df8dd9
CONFIG_KFENCE_NUM_OBJECTS controls the constant memory overhead that KFENCE introduces for its memory pool. By default it is 255 objects (2Mb extra memory), but since concerns have been raised that low-memory devices may not afford that, we are lowering the number of objects to 63 (512Kb extra memory). So far we haven't seen Android devices allocate more than 50 KFENCE objects. Should the kernel exhaust the pool, KFENCE will stop allocating new objects and fall back to SLAB/SLUB until one of the objects is freed. An immediate consequence of reducing the pool size is that a freed KFENCE object will be reused 4x times faster, effectively reducing the probability of detecting a use-after-free. Since KFENCE is a best-effort error detection tool, not a use-after-free mitigation mechanism, we believe this should not be problematic. Bug: 181822795 Test: run KFENCE on an Android device Signed-off-by: Alexander Potapenko <glider@google.com> Change-Id: I88fca80eea8b382115de03dbb104fd305b35476f
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.