0104096498
Currently, VA exhaustion is being checked by passing a hint to mmap() and expecting it to fail. While populating the lower VA space, mmap() fails because we have exhausted the space. Then, in validate_lower_address_hint(), because mmap() fails, we confirm that we have indeed exhausted the space. There is a circular logic involved here. Assume that there is a bug in mmap(), also assume that it exists independent of whether you pass a hint address or not; that for some reason it is not able to find a 1GB chunk. My idea is to assert the exhaustion against some other method. This patch makes a stricter test by successful write() calls from /proc/self/maps to a dump file, confirming that a free chunk is indeed not available. [dev.jain@arm.com: replace SZ_1GB with MAP_CHUNK_SIZE, tidy-up] Link: https://lkml.kernel.org/r/20240325042653.867055-1-dev.jain@arm.com Link: https://lkml.kernel.org/r/20240321103522.516097-1-dev.jain@arm.com Signed-off-by: Dev Jain <dev.jain@arm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Shuah Khan <shuah@kernel.org> 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 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.