ARM: 7641/1: memory: fix broken mmap by ensuring TASK_UNMAPPED_BASE is aligned
We have received multiple reports of mmap failures when running with a 2:2 vm split. These manifest as either -EINVAL with a non page-aligned address (ending 0xaaa) or a SEGV, depending on the application. The issue is commonly observed in children of make, which appears to use bottom-up mmap (assumedly because it changes the stack rlimit). Further investigation reveals that this regression was triggered by 394ef640 ("mm: use vm_unmapped_area() on arm architecture"), whereby TASK_UNMAPPED_BASE is no longer page-aligned for bottom-up mmap, causing get_unmapped_area to choke on misaligned addressed. This patch fixes the problem by defining TASK_UNMAPPED_BASE in terms of TASK_SIZE and explicitly aligns the result to 16M, matching the other end of the heap. Acked-by:Nicolas Pitre <nico@linaro.org> Reported-by:
Steve Capper <steve.capper@arm.com> Reported-by:
Jean-Francois Moine <moinejf@free.fr> Reported-by:
Christoffer Dall <cdall@cs.columbia.edu> Signed-off-by:
Will Deacon <will.deacon@arm.com> Signed-off-by:
Russell King <rmk+kernel@arm.linux.org.uk>
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