Make use of the set_direct_map() calls for module allocations. In particular: - All changes to read-only permissions in kernel VA mappings are also applied to the direct mapping. Note that execute permissions are intentionally not applied to the direct mapping in order to make sure that all allocated pages within the direct mapping stay non-executable - module_alloc() passes the VM_FLUSH_RESET_PERMS to __vmalloc_node_range() to make sure that all implicit permission changes made to the direct mapping are reset when the allocated vm area is freed again Side effects: the direct mapping will be fragmented depending on how many vm areas with VM_FLUSH_RESET_PERMS and/or explicit page permission changes are allocated and freed again. For example, just after boot of a system the direct mapping statistics look like: $cat /proc/meminfo ... DirectMap4k: 111628 kB DirectMap1M: 16665600 kB DirectMap2G: 0 kB Acked-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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.
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