diff --git a/doc/statuscodes.md b/doc/statuscodes.md
index 1cd72df30ad..f2df9e00dec 100644
--- a/doc/statuscodes.md
+++ b/doc/statuscodes.md
@@ -1,9 +1,20 @@
 # Status codes and their use in gRPC
 
-gRPC uses a set of well defined status codes as part of the RPC API. All RPCs started at a client return  a `status` object composed of an integer `code` and a string `message`. The server-side can choose the status it returns for a given RPC.
+gRPC uses a set of well defined status codes as part of the RPC API. All
+RPCs started at a client return  a `status` object composed of an integer
+`code` and a string `message`. The server-side can choose the status it
+returns for a given RPC.
 
-The gRPC client and server-side implementations may also generate and return `status` on their own when errors happen.  
-Only a subset of the pre-defined status codes are generated by the gRPC libraries. The following table lists these codes and summarizes the situations in which they are generated, either by the client or the server-side library implementation.
+The gRPC client and server-side implementations may also generate and
+return `status` on their own when errors happen.  Only a subset of
+the pre-defined status codes are generated by the gRPC libraries.  This
+allows applications to be sure that any other code it sees was actually
+returned by the application (although it is also possible for the
+server-side to return one of the codes generated by the gRPC libraries).
+
+The following table lists the codes that may be returned by the gRPC
+libraries (on either the client-side or server-side) and summarizes the
+situations in which they are generated.
 
 | Case        | Code           | Generated at Client or Server  |
 | ------------- |:-------------| :-----:|
@@ -26,7 +37,7 @@ Only a subset of the pre-defined status codes are generated by the gRPC librarie
 | Response cardinality violation (method requires exactly one response but server sent some other number of responses) | UNIMPLEMENTED | Client|
 | Error parsing response proto	| INTERNAL | Client|
 | Error parsing request proto	| INTERNAL | Server|
-
+| Sent or received message was larger than configured limit | RESOURCE_EXHAUSTED | Both |
 
 The following status codes are never generated by the library:
 - INVALID_ARGUMENT
diff --git a/include/grpc/support/alloc.h b/include/grpc/support/alloc.h
index 541433c6880..017d75a3d0e 100644
--- a/include/grpc/support/alloc.h
+++ b/include/grpc/support/alloc.h
@@ -68,7 +68,8 @@ GPRAPI void gpr_free_aligned(void *ptr);
 
 /** Request the family of allocation functions in \a functions be used. NOTE
  * that this request will be honored in a *best effort* basis and that no
- * guarantees are made about the default functions (eg, malloc) being called. */
+ * guarantees are made about the default functions (eg, malloc) being called.
+ * The functions.free_fn implementation must be a no-op for NULL input. */
 GPRAPI void gpr_set_allocation_functions(gpr_allocation_functions functions);
 
 /** Return the family of allocation functions currently in effect. */
diff --git a/src/core/lib/channel/message_size_filter.c b/src/core/lib/channel/message_size_filter.c
index c12fabb37c0..c80b48ee132 100644
--- a/src/core/lib/channel/message_size_filter.c
+++ b/src/core/lib/channel/message_size_filter.c
@@ -122,7 +122,7 @@ static void recv_message_ready(grpc_exec_ctx* exec_ctx, void* user_data,
                  (*calld->recv_message)->length, calld->max_recv_size);
     grpc_error* new_error = grpc_error_set_int(
         GRPC_ERROR_CREATE_FROM_COPIED_STRING(message_string),
-        GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_INVALID_ARGUMENT);
+        GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_RESOURCE_EXHAUSTED);
     if (error == GRPC_ERROR_NONE) {
       error = new_error;
     } else {
@@ -152,7 +152,7 @@ static void start_transport_stream_op_batch(
         exec_ctx, op,
         grpc_error_set_int(GRPC_ERROR_CREATE_FROM_COPIED_STRING(message_string),
                            GRPC_ERROR_INT_GRPC_STATUS,
-                           GRPC_STATUS_INVALID_ARGUMENT));
+                           GRPC_STATUS_RESOURCE_EXHAUSTED));
     gpr_free(message_string);
     return;
   }
diff --git a/src/core/lib/iomgr/closure.c b/src/core/lib/iomgr/closure.c
index 6633fb68ecf..8ef0b210ad2 100644
--- a/src/core/lib/iomgr/closure.c
+++ b/src/core/lib/iomgr/closure.c
@@ -45,6 +45,9 @@ grpc_closure *grpc_closure_init(grpc_closure *closure, grpc_iomgr_cb_func cb,
   closure->cb = cb;
   closure->cb_arg = cb_arg;
   closure->scheduler = scheduler;
+#ifndef NDEBUG
+  closure->scheduled = false;
+#endif
   return closure;
 }
 
@@ -137,6 +140,10 @@ void grpc_closure_sched(grpc_exec_ctx *exec_ctx, grpc_closure *c,
                         grpc_error *error) {
   GPR_TIMER_BEGIN("grpc_closure_sched", 0);
   if (c != NULL) {
+#ifndef NDEBUG
+    GPR_ASSERT(!c->scheduled);
+    c->scheduled = true;
+#endif
     assert(c->cb);
     c->scheduler->vtable->sched(exec_ctx, c, error);
   } else {
@@ -149,6 +156,10 @@ void grpc_closure_list_sched(grpc_exec_ctx *exec_ctx, grpc_closure_list *list) {
   grpc_closure *c = list->head;
   while (c != NULL) {
     grpc_closure *next = c->next_data.next;
+#ifndef NDEBUG
+    GPR_ASSERT(!c->scheduled);
+    c->scheduled = true;
+#endif
     assert(c->cb);
     c->scheduler->vtable->sched(exec_ctx, c, c->error_data.error);
     c = next;
diff --git a/src/core/lib/iomgr/closure.h b/src/core/lib/iomgr/closure.h
index 2510d50b428..2bedbf00d63 100644
--- a/src/core/lib/iomgr/closure.h
+++ b/src/core/lib/iomgr/closure.h
@@ -99,6 +99,10 @@ struct grpc_closure {
     grpc_error *error;
     uintptr_t scratch;
   } error_data;
+
+#ifndef NDEBUG
+  bool scheduled;
+#endif
 };
 
 /** Initializes \a closure with \a cb and \a cb_arg. Returns \a closure. */
diff --git a/src/core/lib/iomgr/combiner.c b/src/core/lib/iomgr/combiner.c
index 2bc476bbef6..05cdbdad2b7 100644
--- a/src/core/lib/iomgr/combiner.c
+++ b/src/core/lib/iomgr/combiner.c
@@ -319,6 +319,9 @@ bool grpc_combiner_continue_exec_ctx(grpc_exec_ctx *exec_ctx) {
     GPR_TIMER_BEGIN("combiner.exec1", 0);
     grpc_closure *cl = (grpc_closure *)n;
     error_data err = unpack_error_data(cl->error_data.scratch);
+#ifndef NDEBUG
+    cl->scheduled = false;
+#endif
     cl->cb(exec_ctx, cl->cb_arg, err.error);
     if (err.covered_by_poller) {
       gpr_atm_no_barrier_fetch_add(&lock->elements_covered_by_poller, -1);
@@ -337,6 +340,9 @@ bool grpc_combiner_continue_exec_ctx(grpc_exec_ctx *exec_ctx) {
           gpr_log(GPR_DEBUG, "C:%p execute_final[%d] c=%p", lock, loops, c));
       grpc_closure *next = c->next_data.next;
       grpc_error *error = c->error_data.error;
+#ifndef NDEBUG
+      c->scheduled = false;
+#endif
       c->cb(exec_ctx, c->cb_arg, error);
       GRPC_ERROR_UNREF(error);
       c = next;
diff --git a/src/core/lib/iomgr/ev_epoll_linux.c b/src/core/lib/iomgr/ev_epoll_linux.c
index 4a0f91391f2..e603a755937 100644
--- a/src/core/lib/iomgr/ev_epoll_linux.c
+++ b/src/core/lib/iomgr/ev_epoll_linux.c
@@ -1348,6 +1348,9 @@ static bool maybe_do_workqueue_work(grpc_exec_ctx *exec_ctx,
       }
       grpc_closure *c = (grpc_closure *)n;
       grpc_error *error = c->error_data.error;
+#ifndef NDEBUG
+      c->scheduled = false;
+#endif
       c->cb(exec_ctx, c->cb_arg, error);
       GRPC_ERROR_UNREF(error);
       return true;
diff --git a/src/core/lib/iomgr/exec_ctx.c b/src/core/lib/iomgr/exec_ctx.c
index 83bb436bd0a..2532a708e7b 100644
--- a/src/core/lib/iomgr/exec_ctx.c
+++ b/src/core/lib/iomgr/exec_ctx.c
@@ -73,6 +73,9 @@ bool grpc_exec_ctx_flush(grpc_exec_ctx *exec_ctx) {
         grpc_closure *next = c->next_data.next;
         grpc_error *error = c->error_data.error;
         did_something = true;
+#ifndef NDEBUG
+        c->scheduled = false;
+#endif
         c->cb(exec_ctx, c->cb_arg, error);
         GRPC_ERROR_UNREF(error);
         c = next;
@@ -93,6 +96,9 @@ void grpc_exec_ctx_finish(grpc_exec_ctx *exec_ctx) {
 
 static void exec_ctx_run(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
                          grpc_error *error) {
+#ifndef NDEBUG
+  closure->scheduled = false;
+#endif
   closure->cb(exec_ctx, closure->cb_arg, error);
   GRPC_ERROR_UNREF(error);
 }
diff --git a/src/core/lib/iomgr/executor.c b/src/core/lib/iomgr/executor.c
index ae3e2eabc39..75fd5b1c50c 100644
--- a/src/core/lib/iomgr/executor.c
+++ b/src/core/lib/iomgr/executor.c
@@ -83,6 +83,9 @@ static void closure_exec_thread_func(void *ignored) {
       while (c != NULL) {
         grpc_closure *next = c->next_data.next;
         grpc_error *error = c->error_data.error;
+#ifndef NDEBUG
+        c->scheduled = false;
+#endif
         c->cb(&exec_ctx, c->cb_arg, error);
         GRPC_ERROR_UNREF(error);
         c = next;
@@ -146,6 +149,9 @@ void grpc_executor_shutdown(grpc_exec_ctx *exec_ctx) {
   while (c != NULL) {
     grpc_closure *next = c->next_data.next;
     grpc_error *error = c->error_data.error;
+#ifndef NDEBUG
+    c->scheduled = false;
+#endif
     c->cb(exec_ctx, c->cb_arg, error);
     GRPC_ERROR_UNREF(error);
     c = next;
diff --git a/src/core/lib/iomgr/sockaddr_utils.c b/src/core/lib/iomgr/sockaddr_utils.c
index 9d2732666b2..a6a4cac3e29 100644
--- a/src/core/lib/iomgr/sockaddr_utils.c
+++ b/src/core/lib/iomgr/sockaddr_utils.c
@@ -55,7 +55,9 @@ int grpc_sockaddr_is_v4mapped(const grpc_resolved_address *resolved_addr,
   GPR_ASSERT(resolved_addr != resolved_addr4_out);
   const struct sockaddr *addr = (const struct sockaddr *)resolved_addr->addr;
   struct sockaddr_in *addr4_out =
-      (struct sockaddr_in *)resolved_addr4_out->addr;
+      resolved_addr4_out == NULL
+          ? NULL
+          : (struct sockaddr_in *)resolved_addr4_out->addr;
   if (addr->sa_family == AF_INET6) {
     const struct sockaddr_in6 *addr6 = (const struct sockaddr_in6 *)addr;
     if (memcmp(addr6->sin6_addr.s6_addr, kV4MappedPrefix,
diff --git a/src/core/lib/slice/slice.c b/src/core/lib/slice/slice.c
index 1cddf062cd4..a2fcbbdbdf5 100644
--- a/src/core/lib/slice/slice.c
+++ b/src/core/lib/slice/slice.c
@@ -197,6 +197,7 @@ grpc_slice grpc_slice_new_with_len(void *p, size_t len,
 }
 
 grpc_slice grpc_slice_from_copied_buffer(const char *source, size_t length) {
+  if (length == 0) return grpc_empty_slice();
   grpc_slice slice = grpc_slice_malloc(length);
   memcpy(GRPC_SLICE_START_PTR(slice), source, length);
   return slice;
@@ -382,8 +383,9 @@ grpc_slice grpc_slice_split_head(grpc_slice *source, size_t split) {
 }
 
 int grpc_slice_default_eq_impl(grpc_slice a, grpc_slice b) {
-  return GRPC_SLICE_LENGTH(a) == GRPC_SLICE_LENGTH(b) &&
-         0 == memcmp(GRPC_SLICE_START_PTR(a), GRPC_SLICE_START_PTR(b),
+  if (GRPC_SLICE_LENGTH(a) != GRPC_SLICE_LENGTH(b)) return false;
+  if (GRPC_SLICE_LENGTH(a) == 0) return true;
+  return 0 == memcmp(GRPC_SLICE_START_PTR(a), GRPC_SLICE_START_PTR(b),
                      GRPC_SLICE_LENGTH(a));
 }
 
diff --git a/src/core/lib/transport/pid_controller.c b/src/core/lib/transport/pid_controller.c
index 19cb1c0b367..c851564201f 100644
--- a/src/core/lib/transport/pid_controller.c
+++ b/src/core/lib/transport/pid_controller.c
@@ -49,6 +49,7 @@ void grpc_pid_controller_reset(grpc_pid_controller *pid_controller) {
 
 double grpc_pid_controller_update(grpc_pid_controller *pid_controller,
                                   double error, double dt) {
+  if (dt == 0) return pid_controller->last_control_value;
   /* integrate error using the trapezoid rule */
   pid_controller->error_integral +=
       dt * (pid_controller->last_error + error) * 0.5;
diff --git a/test/core/end2end/tests/max_message_length.c b/test/core/end2end/tests/max_message_length.c
index cc371f4e2f4..224c1cd8338 100644
--- a/test/core/end2end/tests/max_message_length.c
+++ b/test/core/end2end/tests/max_message_length.c
@@ -274,7 +274,7 @@ static void test_max_message_length_on_request(grpc_end2end_test_config config,
   GPR_ASSERT(was_cancelled == 1);
 
 done:
-  GPR_ASSERT(status == GRPC_STATUS_INVALID_ARGUMENT);
+  GPR_ASSERT(status == GRPC_STATUS_RESOURCE_EXHAUSTED);
   GPR_ASSERT(
       grpc_slice_str_cmp(
           details, send_limit
@@ -468,7 +468,7 @@ static void test_max_message_length_on_response(grpc_end2end_test_config config,
   GPR_ASSERT(0 ==
              grpc_slice_str_cmp(call_details.host, "foo.test.google.fr:1234"));
 
-  GPR_ASSERT(status == GRPC_STATUS_INVALID_ARGUMENT);
+  GPR_ASSERT(status == GRPC_STATUS_RESOURCE_EXHAUSTED);
   GPR_ASSERT(
       grpc_slice_str_cmp(
           details, send_limit
diff --git a/tools/internal_ci/linux/sanitizer/grpc_cpp_asan.sh b/tools/internal_ci/linux/sanitizer/grpc_cpp_asan.sh
index c3bf79b1fb5..47ccb26f878 100755
--- a/tools/internal_ci/linux/sanitizer/grpc_cpp_asan.sh
+++ b/tools/internal_ci/linux/sanitizer/grpc_cpp_asan.sh
@@ -37,4 +37,4 @@ git submodule update --init
 
 # download docker images from dockerhub
 export DOCKERHUB_ORGANIZATION=grpctesting
-tools/run_tests/run_tests_matrix.py -f cpp asan
+tools/run_tests/run_tests_matrix.py -f c++ asan
diff --git a/tools/internal_ci/linux/sanitizer/grpc_cpp_tsan.sh b/tools/internal_ci/linux/sanitizer/grpc_cpp_tsan.sh
index c72a106c91a..ee3ec5ebb08 100755
--- a/tools/internal_ci/linux/sanitizer/grpc_cpp_tsan.sh
+++ b/tools/internal_ci/linux/sanitizer/grpc_cpp_tsan.sh
@@ -37,4 +37,4 @@ git submodule update --init
 
 # download docker images from dockerhub
 export DOCKERHUB_ORGANIZATION=grpctesting
-tools/run_tests/run_tests_matrix.py -f cpp tsan
+tools/run_tests/run_tests_matrix.py -f c++ tsan