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2017-11-16x86/selftests: Add test for mapping placement for 5-level pagingKirill A. Shutemov
5-level paging provides a 56-bit virtual address space for user space application. But the kernel defaults to mappings below the 47-bit address space boundary, which is the upper bound for 4-level paging, unless an application explicitely request it by using a mmap(2) address hint above the 47-bit boundary. The kernel prevents mappings which spawn across the 47-bit boundary unless mmap(2) was invoked with MAP_FIXED. Add a self-test that covers the corner cases of the interface and validates the correctness of the implementation. [ tglx: Massaged changelog once more ] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lkml.kernel.org/r/20171115143607.81541-2-kirill.shutemov@linux.intel.com