Merge branch 'sverk/trapping-bin2term' into OTP_R16B03

* sverk/trapping-bin2term:
  erts: Adjust term_to_binary reduction factors
  erts: Yield after trapping term_to_binary if gc has been ordered
  erts: Let term_to_binary disable gc while trapping
  erts: Improve stress of binary_to_term in binary_SUITE
  erts: Fix bug in binary_to_term for compressed on halfword
  erts: Fix crash when binary_to_term throws badarg
  erts: Trapping memcpy in binary_to_term
  erts: Cleanup code for trapping binary_to_term
  erts: Add erlang wrappers to binary_to_term
  trapping uncompress
  trapping size calculation
  trapping binary_to_term/2
  trapping STRING_EXT
  trapping lists and tuples
  trapping binary_to_term passing binary_SUITE
  Parallel check_process_code when code_server purge a module
  Functionality for disabling garbage collection
  Use asynchronous check_process_code in code_parallel_SUITE
  Execution of system tasks in context of another process

Conflicts:
	erts/emulator/beam/external.c
	erts/emulator/beam/sys.h
	erts/emulator/test/binary_SUITE.erl
	erts/preloaded/ebin/erlang.beam
	erts/preloaded/ebin/erts_internal.beam

3 files changed, 335 insertions, 61 deletions

diff --git a/erts/emulator/test/binary_SUITE.erl b/erts/emulator/test/binary_SUITE.erl
index a340a805b5..6b5c542b8a 100644
--- a/erts/emulator/test/binary_SUITE.erl
+++ b/erts/emulator/test/binary_SUITE.erl
@@ -447,26 +447,26 @@ terms(Config) when is_list(Config) ->
               Sz1 when is_integer(Sz1), size(Bin1) =< Sz1 ->
                   ok
               end,
-		      Term = binary_to_term(Bin),
-		      Term = binary_to_term(Bin, [safe]),
+		      Term = binary_to_term_stress(Bin),
+		      Term = binary_to_term_stress(Bin, [safe]),
 		      Unaligned = make_unaligned_sub_binary(Bin),
-		      Term = binary_to_term(Unaligned),
-		      Term = binary_to_term(Unaligned, []),
-		      Term = binary_to_term(Bin, [safe]),
+		      Term = binary_to_term_stress(Unaligned),
+		      Term = binary_to_term_stress(Unaligned, []),
+		      Term = binary_to_term_stress(Bin, [safe]),
 		      BinC = erlang:term_to_binary(Term, [compressed]),
-		      Term = binary_to_term(BinC),
+		      Term = binary_to_term_stress(BinC),
 		      true = size(BinC) =< size(Bin),
 		      Bin = term_to_binary(Term, [{compressed,0}]),
 		      terms_compression_levels(Term, size(Bin), 1),
 		      UnalignedC = make_unaligned_sub_binary(BinC),
-		      Term = binary_to_term(UnalignedC)
+		      Term = binary_to_term_stress(UnalignedC)
 	      end,
     ?line test_terms(TestFun),
     ok.
 
 terms_compression_levels(Term, UncompressedSz, Level) when Level < 10 ->
     BinC = erlang:term_to_binary(Term, [{compressed,Level}]),
-    Term = binary_to_term(BinC),
+    Term = binary_to_term_stress(BinC),
     Sz = byte_size(BinC),
     true = Sz =< UncompressedSz,
     terms_compression_levels(Term, UncompressedSz, Level+1);
@@ -476,9 +476,9 @@ terms_float(Config) when is_list(Config) ->
     ?line test_floats(fun(Term) ->
 			      Bin0 = term_to_binary(Term),
 			      Bin0 = term_to_binary(Term, [{minor_version,0}]),
-			      Term = binary_to_term(Bin0),
+			      Term = binary_to_term_stress(Bin0),
 			      Bin1 = term_to_binary(Term, [{minor_version,1}]),
-			      Term = binary_to_term(Bin1),
+			      Term = binary_to_term_stress(Bin1),
 			      true = size(Bin1) < size(Bin0),
                   Size0 = erlang:external_size(Term),
                   Size00 = erlang:external_size(Term, [{minor_version, 0}]),
@@ -490,7 +490,7 @@ terms_float(Config) when is_list(Config) ->
 float_middle_endian(Config) when is_list(Config) ->
     %% Testing for roundtrip is not enough.
     ?line <<131,70,63,240,0,0,0,0,0,0>> = term_to_binary(1.0, [{minor_version,1}]),
-    ?line 1.0 = binary_to_term(<<131,70,63,240,0,0,0,0,0,0>>).
+    ?line 1.0 = binary_to_term_stress(<<131,70,63,240,0,0,0,0,0,0>>).
 
 external_size(Config) when is_list(Config) ->
     %% Build a term whose external size only fits in a big num (on 32-bit CPU).
@@ -608,10 +608,10 @@ bad_binary_to_term(Config) when is_list(Config) ->
     ok.
 
 bad_bin_to_term(BadBin) ->
-    {'EXIT',{badarg,_}} = (catch binary_to_term(BadBin)).
+    {'EXIT',{badarg,_}} = (catch binary_to_term_stress(BadBin)).
 
 bad_bin_to_term(BadBin,Opts) ->
-    {'EXIT',{badarg,_}} = (catch binary_to_term(BadBin,Opts)).
+    {'EXIT',{badarg,_}} = (catch binary_to_term_stress(BadBin,Opts)).
 
 safe_binary_to_term2(doc) -> "Test safety options for binary_to_term/2";
 safe_binary_to_term2(Config) when is_list(Config) ->
@@ -622,7 +622,7 @@ safe_binary_to_term2(Config) when is_list(Config) ->
     BadRef = <<131,114,0,3,BadHostAtom/binary,0,<<0,0,0,255>>/binary,
 	      Empty/binary,Empty/binary>>,
     ?line bad_bin_to_term(BadRef, [safe]), % good ref, with a bad atom
-    ?line fullsweep_after = binary_to_term(<<131,100,0,15,"fullsweep_after">>, [safe]), % should be a good atom
+    ?line fullsweep_after = binary_to_term_stress(<<131,100,0,15,"fullsweep_after">>, [safe]), % should be a good atom
     BadExtFun = <<131,113,100,0,4,98,108,117,101,100,0,4,109,111,111,110,97,3>>,
     ?line bad_bin_to_term(BadExtFun, [safe]),
     ok.
@@ -679,14 +679,14 @@ corrupter0(Term) ->
 
 corrupter(Bin, Pos) when Pos >= 0 ->
     ?line {ShorterBin, Rest} = split_binary(Bin, Pos),
-    ?line catch binary_to_term(ShorterBin), %% emulator shouldn't crash
+    ?line catch binary_to_term_stress(ShorterBin), %% emulator shouldn't crash
     ?line MovedBin = list_to_binary([ShorterBin]),
-    ?line catch binary_to_term(MovedBin), %% emulator shouldn't crash
+    ?line catch binary_to_term_stress(MovedBin), %% emulator shouldn't crash
 
     %% Bit faults, shouldn't crash
     <<Byte,Tail/binary>> = Rest,
     Fun = fun(M) -> FaultyByte = Byte bxor M,                    
-		    catch binary_to_term(<<ShorterBin/binary,
+		    catch binary_to_term_stress(<<ShorterBin/binary,
 					  FaultyByte, Tail/binary>>) end,
     ?line lists:foreach(Fun,[1,2,4,8,16,32,64,128,255]),    
     ?line corrupter(Bin, Pos-1);
@@ -700,7 +700,7 @@ more_bad_terms(Config) when is_list(Config) ->
     ?line ok = io:format("File: ~s\n", [BadFile]),
     ?line case file:read_file(BadFile) of
 	      {ok,Bin} ->
-		  ?line {'EXIT',{badarg,_}} = (catch binary_to_term(Bin)),
+		  ?line {'EXIT',{badarg,_}} = (catch binary_to_term_stress(Bin)),
 		  ok;
 	      Other ->
 		  ?line ?t:fail(Other)
@@ -709,7 +709,7 @@ more_bad_terms(Config) when is_list(Config) ->
 otp_5484(Config) when is_list(Config) ->
     ?line {'EXIT',_} =
 	(catch
-	     binary_to_term(
+	     binary_to_term_stress(
 	       <<131,
 		104,2,				%Tuple, 2 elements
 		103,				%Pid
@@ -722,7 +722,7 @@ otp_5484(Config) when is_list(Config) ->
 
     ?line {'EXIT',_} =
 	(catch
-	     binary_to_term(
+	     binary_to_term_stress(
 	       <<131,
 		104,2,				%Tuple, 2 elements
 		103,				%Pid
@@ -734,13 +734,13 @@ otp_5484(Config) when is_list(Config) ->
 
     ?line {'EXIT',_} =
 	(catch
-	     binary_to_term(
+	     binary_to_term_stress(
 	       %% A old-type fun in a list containing a bad creator pid.
 	       <<131,108,0,0,0,1,117,0,0,0,0,103,100,0,13,110,111,110,111,100,101,64,110,111,104,111,115,116,255,255,0,25,255,0,0,0,0,100,0,1,116,97,0,98,6,142,121,72,106>>)),
 
     ?line {'EXIT',_} =
 	(catch
-	     binary_to_term(
+	     binary_to_term_stress(
 	       %% A new-type fun in a list containing a bad creator pid.
 	       %% 
 	       <<131,
@@ -752,7 +752,7 @@ otp_5484(Config) when is_list(Config) ->
 
     ?line {'EXIT',_} =
 	(catch
-	     binary_to_term(
+	     binary_to_term_stress(
 	       %% A new-type fun in a list containing a bad module.
 	       <<131,
 		108,0,0,0,1,			%List, 1 element
@@ -763,7 +763,7 @@ otp_5484(Config) when is_list(Config) ->
 
     ?line {'EXIT',_} =
 	(catch
-	     binary_to_term(
+	     binary_to_term_stress(
 	       %% A new-type fun in a list containing a bad index.
 	       <<131,
 		108,0,0,0,1,			%List, 1 element
@@ -775,7 +775,7 @@ otp_5484(Config) when is_list(Config) ->
 
     ?line {'EXIT',_} =
 	(catch
-	     binary_to_term(
+	     binary_to_term_stress(
 	       %% A new-type fun in a list containing a bad unique value.
 	       <<131,
 		108,0,0,0,1,			%List, 1 element
@@ -788,46 +788,46 @@ otp_5484(Config) when is_list(Config) ->
 
     %% An absurdly large atom.
     ?line {'EXIT',_} = 
-	(catch binary_to_term(iolist_to_binary([<<131,100,65000:16>>|
+	(catch binary_to_term_stress(iolist_to_binary([<<131,100,65000:16>>|
 						lists:duplicate(65000, 42)]))),
 
     %% Longer than 255 characters.
     ?line {'EXIT',_} = 
-	(catch binary_to_term(iolist_to_binary([<<131,100,256:16>>|
+	(catch binary_to_term_stress(iolist_to_binary([<<131,100,256:16>>|
 						lists:duplicate(256, 42)]))),
 
     %% OTP-7218. Thanks to Matthew Dempsky. Also make sure that we
     %% cover the other error cases for external funs (EXPORT_EXT).
     ?line {'EXIT',_} = 
-	(catch binary_to_term(
+	(catch binary_to_term_stress(
 		 <<131,
 		  113,				%EXPORT_EXP
 		  97,13,			%Integer: 13
 		  97,13,			%Integer: 13
 		  97,13>>)),			%Integer: 13
     ?line {'EXIT',_} = 
-	(catch binary_to_term(
+	(catch binary_to_term_stress(
 		 <<131,
 		  113,				%EXPORT_EXP
 		  100,0,1,64,			%Atom: '@'
 		  97,13,			%Integer: 13
 		  97,13>>)),			%Integer: 13
     ?line {'EXIT',_} = 
-	(catch binary_to_term(
+	(catch binary_to_term_stress(
 		 <<131,
 		  113,				%EXPORT_EXP
 		  100,0,1,64,			%Atom: '@'
 		  100,0,1,64,			%Atom: '@'
 		  106>>)),			%NIL
     ?line {'EXIT',_} = 
-	(catch binary_to_term(
+	(catch binary_to_term_stress(
 		 <<131,
 		  113,				%EXPORT_EXP
 		  100,0,1,64,			%Atom: '@'
 		  100,0,1,64,			%Atom: '@'
 		  98,255,255,255,255>>)),	%Integer: -1
     ?line {'EXIT',_} = 
-	(catch binary_to_term(
+	(catch binary_to_term_stress(
 		 <<131,
 		  113,				%EXPORT_EXP
 		  100,0,1,64,			%Atom: '@'
@@ -835,7 +835,7 @@ otp_5484(Config) when is_list(Config) ->
 		  113,97,13,97,13,97,13>>)),	%fun 13:13/13
 
     %% Bad funs.
-    ?line {'EXIT',_} = (catch binary_to_term(fake_fun(0, lists:seq(0, 256)))),
+    ?line {'EXIT',_} = (catch binary_to_term_stress(fake_fun(0, lists:seq(0, 256)))),
     ok.
 
 fake_fun(Arity, Env0) ->
@@ -869,7 +869,7 @@ try_bad_lengths(B) ->
 try_bad_lengths(B, L) when L > 16#FFFFFFF0 ->
     Bin = <<B/binary,L:32>>,
     io:format("~p\n", [Bin]),
-    {'EXIT',_} = (catch binary_to_term(Bin)),
+    {'EXIT',_} = (catch binary_to_term_stress(Bin)),
     try_bad_lengths(B, L-1);
 try_bad_lengths(_, _) -> ok.
 
@@ -923,7 +923,7 @@ otp_6817_try_bin(Bin) ->
     %% If the bug is present, the heap pointer will moved when the invalid term
     %% is found and we will have a linked list passing through the limbo area
     %% between the heap top and the stack pointer.
-    catch binary_to_term(Bin),
+    catch binary_to_term_stress(Bin),
 
     %% If the bug is present, we will overwrite the pointers in the limbo area.
     Filler = erlang:make_tuple(1024, 16#3FA),
@@ -1233,7 +1233,7 @@ bit_sized_binary_sizes(Config) when is_list(Config) ->
 bsbs_1(A) ->
     BinSize = 32+A,
     io:format("A: ~p BinSize: ~p", [A,BinSize]),
-    Bin = binary_to_term(<<131,$M,5:32,A,0,0,0,0,0>>),
+    Bin = binary_to_term_stress(<<131,$M,5:32,A,0,0,0,0,0>>),
     BinSize = bit_size(Bin).
 
 deep(Config) when is_list(Config) ->
@@ -1250,7 +1250,7 @@ deep(Config) when is_list(Config) ->
 
 deep_roundtrip(T) ->
     B = term_to_binary(T),
-    T = binary_to_term(B).
+    T = binary_to_term_stress(B).
 
 obsolete_funs(Config) when is_list(Config) ->
     erts_debug:set_internal_state(available_internal_state, true),
@@ -1285,29 +1285,29 @@ obsolete_fun(Fun) ->
     Tuple = no_fun_roundtrip(Fun).
 
 no_fun_roundtrip(Term) ->
-    binary_to_term(erts_debug:get_internal_state({term_to_binary_no_funs,Term})).
+    binary_to_term_stress(erts_debug:get_internal_state({term_to_binary_no_funs,Term})).
 
 %% Test non-standard encodings never generated by term_to_binary/1
 %% but recognized by binary_to_term/1.
 
 robustness(Config) when is_list(Config) ->
-    ?line [] = binary_to_term(<<131,107,0,0>>),	%Empty string.
-    ?line [] = binary_to_term(<<131,108,0,0,0,0,106>>),	%Zero-length list.
+    ?line [] = binary_to_term_stress(<<131,107,0,0>>),	%Empty string.
+    ?line [] = binary_to_term_stress(<<131,108,0,0,0,0,106>>),	%Zero-length list.
 
     %% {[],a} where [] is a zero-length list.
-    ?line {[],a} = binary_to_term(<<131,104,2,108,0,0,0,0,106,100,0,1,97>>),
+    ?line {[],a} = binary_to_term_stress(<<131,104,2,108,0,0,0,0,106,100,0,1,97>>),
 
     %% {42,a} where 42 is a zero-length list with 42 in the tail.
-    ?line {42,a} = binary_to_term(<<131,104,2,108,0,0,0,0,97,42,100,0,1,97>>),
+    ?line {42,a} = binary_to_term_stress(<<131,104,2,108,0,0,0,0,97,42,100,0,1,97>>),
 
     %% {{x,y},a} where {x,y} is a zero-length list with {x,y} in the tail.
-    ?line {{x,y},a} = binary_to_term(<<131,104,2,108,0,0,0,0,
+    ?line {{x,y},a} = binary_to_term_stress(<<131,104,2,108,0,0,0,0,
 				      104,2,100,0,1,120,100,0,1,
 				      121,100,0,1,97>>),
 
     %% Bignums fitting in 32 bits.
-    ?line 16#7FFFFFFF = binary_to_term(<<131,98,127,255,255,255>>),
-    ?line -1 = binary_to_term(<<131,98,255,255,255,255>>),
+    ?line 16#7FFFFFFF = binary_to_term_stress(<<131,98,127,255,255,255>>),
+    ?line -1 = binary_to_term_stress(<<131,98,255,255,255,255>>),
     
     ok.
 
@@ -1325,7 +1325,7 @@ run_otp_8180(Name) ->
     ?line {ok,Bins} = file:consult(Name),
     [begin
 	 io:format("~p\n", [Bin]),
-	 ?line {'EXIT',{badarg,_}} = (catch binary_to_term(Bin))
+	 ?line {'EXIT',{badarg,_}} = (catch binary_to_term_stress(Bin))
      end || Bin <- Bins],
     ok.
 
@@ -1394,3 +1394,52 @@ unaligned_sub_bin(Bin0, Offs) ->
     Bin.
 
 id(I) -> I.
+
+
+%% Stress binary_to_term with different initial reductions
+binary_to_term_stress(Bin) ->
+    binary_to_term_stress(Bin, no_opts).
+
+binary_to_term_stress(Bin, Opts) ->
+    Reds = get_reds(),
+    T = b2t(erlang:system_info(context_reductions),
+	    Bin, Opts, catch_binary_to_term(Bin, Opts)),
+    set_reds(Reds),
+    T = case Opts of
+	    no_opts -> binary_to_term(Bin);
+	    _ ->       binary_to_term(Bin,Opts)
+	end.
+
+catch_binary_to_term(Bin, no_opts) ->
+    try binary_to_term(Bin)
+    catch
+	error:badarg -> binary_to_term_throws_badarg
+    end;
+catch_binary_to_term(Bin, Opts) ->
+    try binary_to_term(Bin, Opts)
+    catch
+	error:badarg -> binary_to_term_throws_badarg
+    end.
+
+b2t(0, _Bin, _Opts, Term) ->
+    Term;
+b2t(Reds, Bin, Opts, Term) ->
+    set_reds(Reds),
+    Term = catch_binary_to_term(Bin,Opts),
+    b2t(Reds div 3, Bin, Opts, Term).
+
+set_reds(Reds) ->
+    try	erts_debug:set_internal_state(reds_left, Reds)
+    catch
+	error:undef ->
+	    erts_debug:set_internal_state(available_internal_state, true),
+	    set_reds(Reds)
+    end.
+
+get_reds() ->
+    try	erts_debug:get_internal_state(reds_left)
+    catch
+	error:undef ->
+	    erts_debug:set_internal_state(available_internal_state, true),
+	    get_reds()
+    end.
diff --git a/erts/emulator/test/code_parallel_load_SUITE.erl b/erts/emulator/test/code_parallel_load_SUITE.erl
index 1cfe015ea6..428f1242ab 100644
--- a/erts/emulator/test/code_parallel_load_SUITE.erl
+++ b/erts/emulator/test/code_parallel_load_SUITE.erl
@@ -159,22 +159,34 @@ setup_checkers(_,0) -> [];
 setup_checkers(T,N) -> [spawn_link(fun() -> ?model:check(T) end) | setup_checkers(T, N-1)].
 
 check_and_purge_processes_code(Pids, M) ->
-    check_and_purge_processes_code(Pids, M, []).
-check_and_purge_processes_code([], M, []) ->
+    Tag = make_ref(),
+    N = request_cpc(Pids, M, Tag),
+    ok = handle_cpc_responses(N, Tag, M),
     erlang:purge_module(M),
+    ok.
+
+request_cpc(Pid, M, Tag) when is_pid(Pid) ->
+    erlang:check_process_code(Pid, M, [{async, {Tag, Pid}}]),
+    1;
+request_cpc(Pids, M, Tag) when is_list(Pids) ->
+    request_cpc(Pids, M, Tag, 0).
+
+request_cpc([], _M, _Tag, N) ->
+    N;
+request_cpc([Pid|Pids], M, Tag, N) ->
+    request_cpc(Pids, M, Tag, N + request_cpc(Pid, M, Tag)).
+
+handle_cpc_responses(0, _Tag, _Module) ->
     ok;
-check_and_purge_processes_code([], M, Pending) ->
-    io:format("Processes ~w are still executing old code - retrying.~n", [Pending]),
-    check_and_purge_processes_code(Pending, M, []);
-check_and_purge_processes_code([Pid|Pids], M, Pending) ->
-    case erlang:check_process_code(Pid, M) of
-	false ->
-	    check_and_purge_processes_code(Pids, M, Pending);
-	true ->
-	    check_and_purge_processes_code(Pids, M, [Pid|Pending])
+handle_cpc_responses(N, Tag, Module) ->
+    receive
+	{check_process_code, {Tag, _Pid}, false} ->
+	    handle_cpc_responses(N-1, Tag, Module);
+	{check_process_code, {Tag, Pid}, true} ->
+	    1 = request_cpc(Pid, Module, Tag),
+	    handle_cpc_responses(N, Tag, Module)
     end.
 
-
 generate(Module, Attributes, FunStrings) ->
     FunForms = function_forms(FunStrings),
     Forms    = [
diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index e3aae17df4..bf31655066 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -51,7 +51,13 @@
 	 processes_term_proc_list/1,
 	 otp_7738_waiting/1, otp_7738_suspended/1,
 	 otp_7738_resume/1,
-	 garb_other_running/1]).
+	 garb_other_running/1,
+	 no_priority_inversion/1,
+	 no_priority_inversion2/1,
+	 system_task_blast/1,
+	 system_task_on_suspended/1,
+	 gc_request_when_gc_disabled/1,
+	 gc_request_blast_when_gc_disabled/1]).
 -export([prio_server/2, prio_client/2]).
 
 -export([init_per_testcase/2, end_per_testcase/2]).
@@ -73,7 +79,8 @@ all() ->
      bad_register, garbage_collect, process_info_messages,
      process_flag_badarg, process_flag_heap_size,
      spawn_opt_heap_size, otp_6237, {group, processes_bif},
-     {group, otp_7738}, garb_other_running].
+     {group, otp_7738}, garb_other_running,
+     {group, system_task}].
 
 groups() -> 
     [{t_exit_2, [],
@@ -87,7 +94,11 @@ groups() ->
        processes_gc_trap, processes_term_proc_list]},
      {otp_7738, [],
       [otp_7738_waiting, otp_7738_suspended,
-       otp_7738_resume]}].
+       otp_7738_resume]},
+     {system_task, [],
+      [no_priority_inversion, no_priority_inversion2,
+       system_task_blast, system_task_on_suspended,
+       gc_request_when_gc_disabled, gc_request_blast_when_gc_disabled]}].
 
 init_per_suite(Config) ->
     A0 = case application:start(sasl) of
@@ -2214,6 +2225,208 @@ garb_other_running(Config) when is_list(Config) ->
     receive {'DOWN', Mon, process, Pid, normal} -> ok end,
     ok.
 
+no_priority_inversion(Config) when is_list(Config) ->
+    Prio = process_flag(priority, max),
+    HTLs = lists:map(fun (_) ->
+			     spawn_opt(fun () ->
+					       tok_loop()
+				       end,
+				       [{priority, high}, monitor, link])
+		     end,
+		     lists:seq(1, 2*erlang:system_info(schedulers))),
+    receive after 500 -> ok end,
+    LTL = spawn_opt(fun () ->
+			    tok_loop()
+		    end,
+		    [{priority, low}, monitor, link]),
+    false = erlang:check_process_code(element(1, LTL), nonexisting_module),
+    true = erlang:garbage_collect(element(1, LTL)),
+    lists:foreach(fun ({P, _}) ->
+			  unlink(P),
+			  exit(P, kill)
+		  end, [LTL | HTLs]),
+    lists:foreach(fun ({P, M}) ->
+			  receive
+			      {'DOWN', M, process, P, killed} ->
+				  ok
+			  end
+		  end, [LTL | HTLs]),
+    process_flag(priority, Prio),
+    ok.
+
+no_priority_inversion2(Config) when is_list(Config) ->
+    Prio = process_flag(priority, max),
+    MTLs = lists:map(fun (_) ->
+			     spawn_opt(fun () ->
+					       tok_loop()
+				       end,
+				       [{priority, max}, monitor, link])
+		     end,
+		     lists:seq(1, 2*erlang:system_info(schedulers))),
+    receive after 500 -> ok end,
+    {PL, ML} = spawn_opt(fun () ->
+			       tok_loop()
+		       end,
+		       [{priority, low}, monitor, link]),
+    RL = request_gc(PL, low),
+    RN = request_gc(PL, normal),
+    RH = request_gc(PL, high),
+    receive
+	{garbage_collect, _, _} ->
+	    ?t:fail(unexpected_gc)
+    after 1000 ->
+	    ok
+    end,
+    RM = request_gc(PL, max),
+    receive
+	{garbage_collect, RM, true} ->
+	    ok
+    end,
+    lists:foreach(fun ({P, _}) ->
+			  unlink(P),
+			  exit(P, kill)
+		  end, MTLs),
+    lists:foreach(fun ({P, M}) ->
+			  receive
+			      {'DOWN', M, process, P, killed} ->
+				  ok
+			  end
+		  end, MTLs),
+    receive
+	{garbage_collect, RH, true} ->
+	    ok
+    end,
+    receive
+	{garbage_collect, RN, true} ->
+	    ok
+    end,
+    receive
+	{garbage_collect, RL, true} ->
+	    ok
+    end,
+    unlink(PL),
+    exit(PL, kill),
+    receive
+	{'DOWN', ML, process, PL, killed} ->
+	    ok
+    end,
+    process_flag(priority, Prio),
+    ok.
+
+request_gc(Pid, Prio) ->
+    Ref = make_ref(),
+    erts_internal:request_system_task(Pid, Prio, {garbage_collect, Ref}),
+    Ref.
+
+system_task_blast(Config) when is_list(Config) ->
+    Me = self(),
+    GCReq = fun () ->
+		    RL = gc_req(Me, 100),
+		    lists:foreach(fun (R) ->
+					  receive
+					      {garbage_collect, R, true} ->
+						  ok
+					  end
+				  end, RL),
+		    exit(it_worked)
+	    end,
+    HTLs = lists:map(fun (_) -> spawn_monitor(GCReq) end, lists:seq(1, 1000)),
+    lists:foreach(fun ({P, M}) ->
+			  receive
+			      {'DOWN', M, process, P, it_worked} ->
+				  ok
+			  end
+		  end, HTLs),
+    ok.
+
+gc_req(_Pid, 0) ->
+    [];
+gc_req(Pid, N) ->
+    R0 = request_gc(Pid, low),
+    R1 = request_gc(Pid, normal),
+    R2 = request_gc(Pid, high),
+    R3 = request_gc(Pid, max),
+    [R0, R1, R2, R3 | gc_req(Pid, N-1)].
+
+system_task_on_suspended(Config) when is_list(Config) ->
+    {P, M} = spawn_monitor(fun () ->
+				   tok_loop()
+			   end),
+    true = erlang:suspend_process(P),
+    {status, suspended} = process_info(P, status),
+    true = erlang:garbage_collect(P),
+    {status, suspended} = process_info(P, status),
+    true = erlang:resume_process(P),
+    false = ({status, suspended} == process_info(P, status)),
+    exit(P, kill),
+    receive
+	{'DOWN', M, process, P, killed} ->
+	    ok
+    end.
+
+gc_request_when_gc_disabled(Config) when is_list(Config) ->
+    Master = self(),
+    AIS = erts_debug:set_internal_state(available_internal_state, true),
+    {P, M} = spawn_opt(fun () ->
+			       true = erts_debug:set_internal_state(gc_state,
+								    false),
+			       Master ! {self(), gc_state, false},
+			       receive after 1000 -> ok end,
+			       Master ! {self(), gc_state, true},
+			       false = erts_debug:set_internal_state(gc_state,
+								     true),
+			       receive after 100 -> ok end
+		       end, [monitor, link]),
+    receive {P, gc_state, false} -> ok end,
+    ReqId = make_ref(),
+    async = garbage_collect(P, [{async, ReqId}]),
+    receive
+	{garbage_collect, ReqId, Result} ->
+	    ?t:fail({unexpected_gc, Result});
+	{P, gc_state, true} ->
+	    ok
+    end,
+    receive {garbage_collect, ReqId, true} -> ok end,
+    erts_debug:set_internal_state(available_internal_state, AIS),
+    receive {'DOWN', M, process, P, _Reason} -> ok end,
+    ok.
+
+gc_request_blast_when_gc_disabled(Config) when is_list(Config) ->
+    Master = self(),
+    AIS = erts_debug:set_internal_state(available_internal_state, true),
+    {P, M} = spawn_opt(fun () ->
+			       true = erts_debug:set_internal_state(gc_state,
+								    false),
+			       Master ! {self(), gc_state, false},
+			       receive after 1000 -> ok end,
+			       false = erts_debug:set_internal_state(gc_state,
+								     true),
+			       receive after 100 -> ok end
+		       end, [monitor, link]),
+    receive {P, gc_state, false} -> ok end,
+    PMs = lists:map(fun (N) ->
+			    Prio = case N rem 4 of
+				       0 -> max;
+				       1 -> high;
+				       2 -> normal;
+				       3 -> low
+				   end,
+			    spawn_opt(fun () ->
+					      erlang:garbage_collect(P)
+				      end, [monitor, link, {priority, Prio}])
+		    end, lists:seq(1, 10000)),
+    lists:foreach(fun ({Proc, Mon}) ->
+			  receive
+			      {'DOWN', Mon, process, Proc, normal} ->
+				  ok
+			  end
+		  end,
+		  PMs),
+    erts_debug:set_internal_state(available_internal_state, AIS),
+    receive {'DOWN', M, process, P, _Reason} -> ok end,
+    ok.
+
+
 %% Internal functions
 
 wait_until(Fun) ->