ARM: 7641/1: memory: fix broken mmap by ensuring TASK_UNMAPPED_BASE is aligned
authorWill Deacon <will.deacon@arm.com>
Fri, 8 Feb 2013 11:52:29 +0000 (12:52 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Fri, 8 Feb 2013 12:21:07 +0000 (12:21 +0000)
commit79d1f5c9acf9fc8d06e5537083b19114ce87159f
treef19d70755c5b4ce98e097d43830c969e267f91aa
parent633dc92a28fc3fea6f08ef34de0b353ff5f9bf08
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
394ef6403abc ("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>
arch/arm/include/asm/memory.h