mm: add a field to store names for private anonymous memory

Userspace processes often have multiple allocators that each do
anonymous mmaps to get memory.  When examining memory usage of
individual processes or systems as a whole, it is useful to be
able to break down the various heaps that were allocated by
each layer and examine their size, RSS, and physical memory
usage.

This patch adds a user pointer to the shared union in
vm_area_struct that points to a null terminated string inside
the user process containing a name for the vma.  vmas that
point to the same address will be merged, but vmas that
point to equivalent strings at different addresses will
not be merged.

Userspace can set the name for a region of memory by calling
prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned long)name);
Setting the name to NULL clears it.

The names of named anonymous vmas are shown in /proc/pid/maps
as [anon:<name>] and in /proc/pid/smaps in a new "Name" field
that is only present for named vmas.  If the userspace pointer
is no longer valid all or part of the name will be replaced
with "<fault>".

The idea to store a userspace pointer to reduce the complexity
within mm (at the expense of the complexity of reading
/proc/pid/mem) came from Dave Hansen.  This results in no
runtime overhead in the mm subsystem other than comparing
the anon_name pointers when considering vma merging.  The pointer
is stored in a union with fieds that are only used on file-backed
mappings, so it does not increase memory usage.

Change-Id: Ie2ffc0967d4ffe7ee4c70781313c7b00cf7e3092
Signed-off-by: Colin Cross <ccross@android.com>
mm: fix anon vma naming

Fix two bugs caused by merging anon vma_naming, a typo in
mempolicy.c and a bad merge in sys.c.

Change-Id: Ia4ced447d50573e68195e95ea2f2b4d9456b8a90
Signed-off-by: Colin Cross <ccross@android.com>
gpu: ion: system_heap: add support for 2MB allocations

Enable 2MB (order 9) allocations from the system heap. This improves the
performance of some heavyweight use cases. The benefit is especially
large for use cases where the buffer is mapped into an IOMMU since we
can leverage the 2MB IOMMU page table mappings.

Change-Id: I869733089b9ccba8090bbca80aac7b5f248b335e
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
ion: use iounmap instead of __arm_iounmap

The API iounmap() is more generic and portable
than __arm_iounmap().

Change-Id: If9601e9266bec56442686d3f2bdb1d475cd7bead
Signed-off-by: Larry Bassel <lbassel@codeaurora.org>
ion: use PAGE_KERNEL instead of pgprot_kernel

The ion code uses PAGE_KERNEL (which is more generic than
pgprot_kernel) everywhere except in one place (so fix it).

Change-Id: I38fa1c682a3e04e9c8cb3cd25678094862fe8c9c
Signed-off-by: Larry Bassel <lbassel@codeaurora.org>
Revert "msm: mdss: delay freeing buffers for additional vsync"

This reverts commit 6c3274f8170e1411583f6145f7bc615021ac8b25.

Conflicts:
	drivers/video/msm/mdss/mdss_mdp.h
	drivers/video/msm/mdss/mdss_mdp_overlay.c

Change-Id: I86dab797e95bd9f56b513b3bb6c45c385f65d08c