[3.11] pythongh-114331: Skip decimal test_maxcontext_exact_arith on s…

…390x (python#117326) (python#117331)

pythongh-114331: Skip decimal test_maxcontext_exact_arith on s390x (python#117326)

Add test.support.skip_on_s390x decorator.

(cherry picked from commit 6702d2b)

Lib/test/support/__init__.py

@@ -56,6 +56,7 @@
     "run_with_tz", "PGO", "missing_compiler_executable",
     "ALWAYS_EQ", "NEVER_EQ", "LARGEST", "SMALLEST",
     "LOOPBACK_TIMEOUT", "INTERNET_TIMEOUT", "SHORT_TIMEOUT", "LONG_TIMEOUT",
+    "skip_on_s390x",
     ]
 
 
@@ -2238,3 +2239,7 @@ def copy_python_src_ignore(path, names):
             'build',
         }
     return ignored
+
+#Windows doesn't have os.uname() but it doesn't support s390x.
+skip_on_s390x = unittest.skipIf(hasattr(os, 'uname') and os.uname().machine == 's390x',
+                                'skipped on s390x')

Lib/test/test_decimal.py

@@ -37,7 +37,8 @@
                           requires_legacy_unicode_capi, check_sanitizer)
 from test.support import (TestFailed,
                           run_with_locale, cpython_only,
-                          darwin_malloc_err_warning, is_emscripten)
+                          darwin_malloc_err_warning, is_emscripten,
+                          skip_on_s390x)
 from test.support.import_helper import import_fresh_module
 from test.support import threading_helper
 from test.support import warnings_helper
@@ -5654,6 +5655,9 @@ def __abs__(self):
     @unittest.skipIf(check_sanitizer(address=True, memory=True),
                      "ASAN/MSAN sanitizer defaults to crashing "
                      "instead of returning NULL for malloc failure.")
+    # gh-114331: The test allocates 784 271 641 GiB and mimalloc does not fail
+    # to allocate it when using mimalloc on s390x.
+    @skip_on_s390x
     def test_maxcontext_exact_arith(self):
 
         # Make sure that exact operations do not raise MemoryError due