UPSTREAM: lib: introduce test_meminit module

Upstream commit 5015a300a522 ("lib: introduce test_meminit module").

Add tests for heap and pagealloc initialization.  These can be used to
check init_on_alloc and init_on_free implementations as well as other
approaches to initialization.

Expected test output in the case the kernel provides heap initialization
(e.g.  when running with either init_on_alloc=1 or init_on_free=1):

  test_meminit: all 10 tests in test_pages passed
  test_meminit: all 40 tests in test_kvmalloc passed
  test_meminit: all 60 tests in test_kmemcache passed
  test_meminit: all 10 tests in test_rcu_persistent passed
  test_meminit: all 120 tests passed!

Link: http://lkml.kernel.org/r/20190529123812.43089-4-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Change-Id: I815efdc79304ae1ad6ef60277ac5b88a4c41d479
Bug: 138435492
Test: Boot cuttlefish with and without
Test:   CONFIG_INIT_ON_ALLOC_DEFAULT_ON/CONFIG_INIT_ON_FREE_DEFAULT_ON
Signed-off-by: Alexander Potapenko <glider@google.com>

lib/Kconfig.debug

@@ -1966,6 +1966,14 @@ config TEST_DEBUG_VIRTUAL
 
 	  If unsure, say N.
 
+config TEST_MEMINIT
+	tristate "Test heap/page initialization"
+	help
+	  Test if the kernel is zero-initializing heap and page allocations.
+	  This can be useful to test init_on_alloc and init_on_free features.
+
+	  If unsure, say N.
+
 endif # RUNTIME_TESTING_MENU
 
 config MEMTEST