Merge branch tmp-3991549f into msm-3.18

This merge brings KASAN (Kernel Address Sanitizer) patches from the upstream
to msm-3.18 kernel.

* (31 commits):
  arm64: expose number of page table levels on Kconfig level
  arm64: move PGD_SIZE definition to pgalloc.h
  arm64: pgalloc: consistently use PGALLOC_GFP
  mm, slub, kasan: enable user tracking by default with KASAN=y
  kasan: various fixes in documentation
  kasan: always taint kernel on report
  kasan: update reference to kasan prototype repo
  kasan: update log messages
  kasan: accurately determine the type of the bad access
  kasan: update reported bug types for kernel memory accesses
  kasan: update reported bug types for not user nor kernel memory accesses
  mm/kasan: prevent deadlock in kasan reporting
  mm/kasan: don't use kasan shadow pointer in generic functions
  mm/kasan: MODULE_VADDR is not available on all archs
  mm/kasan: rename kasan_enabled() to kasan_report_enabled()
  .mailmap: Andrey Ryabinin has moved
  lib/Kconfig.debug: disable -Wframe-larger-than warnings with KASAN=y
  compiler, atomics, kasan: Provide READ_ONCE_NOCHECK()
  locking: Remove atomicy checks from {READ,WRITE}_ONCE
  compiler-gcc: integrate the various compiler-gcc[345].h files
  compiler-gcc.h: neatening
  lib: make memzero_explicit more robust against dead store elimination
  Documentation/features/KASAN: arm64 supports KASAN now
  Documentation/features/debug: Add feature description and arch support status file for 'KASAN'
  arm64: add KASAN support
  x86/kasan, mm: Introduce generic kasan_populate_zero_shadow()
  arm64: introduce VA_START macro - the first kernel virtual address.
  x86/kasan: Define KASAN_SHADOW_OFFSET per architecture
  x86/kasan: Move KASAN_SHADOW_OFFSET to the arch Kconfig
  mm/mempool.c: kasan: poison mempool elements
  mm, mempool: poison elements backed by slab allocator

Change-Id: I1a829f2aee91f74de0ad7a4046fba533e4e65e20
Signed-off-by: Trilok Soni <tsoni@codeaurora.org>