3b06ac6707
Today there is a global limit of pages mapped via /dev/xen/gntdev set to 1 million pages per default. There is no reason why that limit is existing, as total number of grant mappings is limited by the hypervisor anyway and preferring kernel mappings over userspace ones doesn't make sense. It should be noted that the gntdev device is usable by root only. Additionally checking of that limit is fragile, as the number of pages to map via one call is specified in a 32-bit unsigned variable which isn't tested to stay within reasonable limits (the only test is the value to be <= zero, which basically excludes only calls without any mapping requested). So trying to map e.g. 0xffff0000 pages while already nearly 1000000 pages are mapped will effectively lower the global number of mapped pages such that a parallel call mapping a reasonable amount of pages can succeed in spite of the global limit being violated. So drop the global limit and introduce per call limit instead. This per call limit (default: 65536 grant mappings) protects against allocating insane large arrays in the kernel for doing a hypercall which will fail anyway in case a user is e.g. trying to map billions of pages. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com> |
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
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.