fix(stdune): fix TSAN warning in wait4_stubs #10554

emillon · 2024-05-21T15:07:11Z

Quoting @jmid, using a local variable without the runtime lock in place, is against the rules. For integer values, sometimes the rules are bent, but this is not a good idea. See ocaml/ocaml#12737.

@jmid

Fixes ocaml#10553 Quoting @jmid, using a local variable without the runtime lock in place, is against the rules. For integer values, sometimes the rules are bent, but this is not a good idea. See ocaml/ocaml#12737. Signed-off-by: Etienne Millon <me@emillon.org>

OlivierNicole

I expect this to remove the TSan warning.

emillon · 2024-05-21T15:29:22Z

Yes, I'm double checking it does indeed.

emillon · 2024-05-21T15:56:56Z

It's displaying another warning:

WARNING: ThreadSanitizer: data race (pid=310426)
  Atomic write of size 8 at 0x7fff7f467ce0 by thread T4 (mutexes: write M0, write M1):
    #0 oldify_one runtime/minor_gc.c:250 (dune.exe+0xe7153d) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #1 caml_do_local_roots runtime/roots.c:64 (dune.exe+0xe767f6) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #2 caml_thread_scan_roots /tmp/tsan/_opam/.opam-switch/build/ocaml-variants.5.2.0+options/otherlibs/systhreads/st_stubs.c:179 (dune.exe+0xe21bad) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #3 caml_empty_minor_heap_promote runtime/minor_gc.c:615 (dune.exe+0xe72861) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #4 caml_stw_empty_minor_heap_no_major_slice runtime/minor_gc.c:746 (dune.exe+0xe72c9d) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #5 caml_stw_empty_minor_heap runtime/minor_gc.c:777 (dune.exe+0xe72f72) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #6 caml_try_run_on_all_domains_with_spin_work runtime/domain.c:1576 (dune.exe+0xe4dedd) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #7 caml_try_empty_minor_heap_on_all_domains runtime/minor_gc.c:808 (dune.exe+0xe730d1) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #8 caml_empty_minor_heaps_once runtime/minor_gc.c:829 (dune.exe+0xe730d1)
    #9 caml_poll_gc_work runtime/domain.c:1745 (dune.exe+0xe4d760) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #10 caml_handle_gc_interrupt runtime/domain.c:1778 (dune.exe+0xe4e595) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #11 caml_do_pending_actions_exn runtime/signals.c:341 (dune.exe+0xe7c423) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #12 caml_process_pending_actions_with_root_exn runtime/signals.c:386 (dune.exe+0xe7c423)
    #13 caml_process_pending_actions_with_root runtime/signals.c:395 (dune.exe+0xe7c537) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #14 caml_process_pending_actions runtime/signals.c:406 (dune.exe+0xe7c537)
    #15 caml_garbage_collection runtime/signals_nat.c:71 (dune.exe+0xe8996c) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #16 caml_call_gc <null> (dune.exe+0xe87551) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #17 camlDune_engine__Scheduler.run_2600 src/dune_engine/scheduler.ml:592 (dune.exe+0xbc5502) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #18 camlDune_engine__Scheduler.f_1696 src/dune_engine/scheduler.ml:97 (dune.exe+0xbc262d) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #19 camlThread.fun_768 /tmp/tsan/_opam/.opam-switch/build/ocaml-variants.5.2.0+options/otherlibs/systhreads/thread.ml:48 (dune.exe+0xd4d800) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #20 caml_start_program <null> (dune.exe+0xe878c3) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #21 caml_callback_exn runtime/callback.c:201 (dune.exe+0xe48b83) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #22 caml_thread_start /tmp/tsan/_opam/.opam-switch/build/ocaml-variants.5.2.0+options/otherlibs/systhreads/st_stubs.c:634 (dune.exe+0xe23547) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)

  Previous read of size 8 at 0x7fff7f467ce0 by main thread:
    #0 caml_unix_mkdir /tmp/tsan/_opam/.opam-switch/build/ocaml-variants.5.2.0+options/otherlibs/unix/mkdir.c:37 (dune.exe+0xe2461f) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #1 caml_c_call <null> (dune.exe+0xe877a7) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #2 camlStdune__Fpath.mkdir_inner_1135 otherlibs/stdune/src/fpath.ml:19 (dune.exe+0xce91e2) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #3 camlStdune__Fpath.mkdir_p_772 otherlibs/stdune/src/fpath.ml:31 (dune.exe+0xce9353) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #4 camlStdune__Path.mkdir_p_5475 otherlibs/stdune/src/path.ml:598 (dune.exe+0xcd015d) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #5 camlDune_engine__Build_system.maybe_async_rule_file_op_3529 src/dune_engine/build_system.ml:324 (dune.exe+0xb2162d) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #6 camlDune_engine__Build_system.f_6677 src/dune_engine/build_system.ml:500 (dune.exe+0xb23b18) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #7 caml_apply2 <null> (dune.exe+0x5d9317) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #8 camlFiber__Scheduler.advance_1194 vendor/fiber/src/scheduler.ml:194 (dune.exe+0xc5cdf8) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #9 camlFiber.loop_393 vendor/fiber/src/fiber.ml:15 (dune.exe+0xc5261b) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #10 camlDune_engine__Scheduler.run_3178 vendor/fiber/src/fiber.ml:17 (dune.exe+0xbc7fd6) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #11 caml_startup_common runtime/startup_nat.c:132 (dune.exe+0xe87070) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #12 caml_startup_common runtime/startup_nat.c:88 (dune.exe+0xe87070)
    #13 caml_startup_exn runtime/startup_nat.c:139 (dune.exe+0xe87117) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #14 caml_startup runtime/startup_nat.c:144 (dune.exe+0xe87117)
    #15 caml_main runtime/startup_nat.c:151 (dune.exe+0xe87117)
    #16 main runtime/main.c:37 (dune.exe+0x5cdbe5) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)

  Location is stack of main thread.

  Location is global '<null>' at 0x000000000000 ([stack]+0x1ece0)

  Mutex M0 (0x720c000003f0) created at:
    #0 pthread_mutex_init ../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:1315 (libtsan.so.2+0x550bf) (BuildId: 4696c58f898e5d5cf4fe08e45868ac4fc5702473)
    #1 sync_mutex_create runtime/sync_posix.h:46 (dune.exe+0xe7eeba) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #2 caml_ml_mutex_new runtime/sync.c:77 (dune.exe+0xe7eeba)
    #3 caml_c_call <null> (dune.exe+0xe877a7) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #4 camlDune_engine__Scheduler.init_2603 src/dune_engine/scheduler.ml:598 (dune.exe+0xbc55fb) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #5 camlDune_engine__Scheduler.prepare_3124 src/dune_engine/scheduler.ml:934 (dune.exe+0xbc7728) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #6 camlDune_engine__Scheduler.go_inner_5417 src/dune_engine/scheduler.ml:1249 (dune.exe+0xbca8c8) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #7 camlCmdliner_term.fun_639 vendor/cmdliner/src/cmdliner_term.ml:24 (dune.exe+0xd31242) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #8 camlCmdliner_eval.run_parser_576 vendor/cmdliner/src/cmdliner_eval.ml:34 (dune.exe+0xd28d05) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #9 camlCmdliner_eval.eval_value_inner_1700 vendor/cmdliner/src/cmdliner_eval.ml:202 (dune.exe+0xd2a584) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #10 camlMain.entry bin/main.ml:106 (dune.exe+0x5d9b29) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #11 caml_program <null> (dune.exe+0x5d15b9) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #12 caml_start_program <null> (dune.exe+0xe878c3) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #13 caml_startup_common runtime/startup_nat.c:132 (dune.exe+0xe87070) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #14 caml_startup_common runtime/startup_nat.c:88 (dune.exe+0xe87070)
    #15 caml_startup_exn runtime/startup_nat.c:139 (dune.exe+0xe87117) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #16 caml_startup runtime/startup_nat.c:144 (dune.exe+0xe87117)
    #17 caml_main runtime/startup_nat.c:151 (dune.exe+0xe87117)
    #18 main runtime/main.c:37 (dune.exe+0x5cdbe5) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)

  Mutex M1 (0x561dd37603c8) created at:
    #0 pthread_mutex_init ../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:1315 (libtsan.so.2+0x550bf) (BuildId: 4696c58f898e5d5cf4fe08e45868ac4fc5702473)
    #1 caml_plat_mutex_init runtime/platform.c:57 (dune.exe+0xe75aa2) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #2 caml_init_domains runtime/domain.c:943 (dune.exe+0xe4ca7e) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #3 caml_init_gc runtime/gc_ctrl.c:353 (dune.exe+0xe5aa5f) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #4 caml_startup_common runtime/startup_nat.c:111 (dune.exe+0xe86f5f) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #5 caml_startup_common runtime/startup_nat.c:88 (dune.exe+0xe86f5f)
    #6 caml_startup_exn runtime/startup_nat.c:139 (dune.exe+0xe87117) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #7 caml_startup runtime/startup_nat.c:144 (dune.exe+0xe87117)
    #8 caml_main runtime/startup_nat.c:151 (dune.exe+0xe87117)
    #9 main runtime/main.c:37 (dune.exe+0x5cdbe5) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)

  Thread T4 (tid=310432, running) created by main thread at:
    #0 pthread_create ../../../../src/libsanitizer/tsan/tsan_interceptors_posix.cpp:1022 (libtsan.so.2+0x564a6) (BuildId: 4696c58f898e5d5cf4fe08e45868ac4fc5702473)
    #1 st_thread_create /tmp/tsan/_opam/.opam-switch/build/ocaml-variants.5.2.0+options/otherlibs/systhreads/st_pthreads.h:57 (dune.exe+0xe236b5) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #2 caml_thread_new /tmp/tsan/_opam/.opam-switch/build/ocaml-variants.5.2.0+options/otherlibs/systhreads/st_stubs.c:685 (dune.exe+0xe236b5)
    #3 caml_c_call <null> (dune.exe+0xe877a7) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #4 camlThread.create_288 /tmp/tsan/_opam/.opam-switch/build/ocaml-variants.5.2.0+options/otherlibs/systhreads/thread.ml:45 (dune.exe+0xd4d779) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #5 camlDune_engine__Scheduler.spawn_1693 src/dune_engine/scheduler.ml:102 (dune.exe+0xbc2595) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #6 camlDune_engine__Scheduler.init_2603 src/dune_engine/scheduler.ml:605 (dune.exe+0xbc5680) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #7 camlDune_engine__Scheduler.prepare_3124 src/dune_engine/scheduler.ml:934 (dune.exe+0xbc7728) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #8 camlDune_engine__Scheduler.go_inner_5417 src/dune_engine/scheduler.ml:1249 (dune.exe+0xbca8c8) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #9 camlCmdliner_term.fun_639 vendor/cmdliner/src/cmdliner_term.ml:24 (dune.exe+0xd31242) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #10 camlCmdliner_eval.run_parser_576 vendor/cmdliner/src/cmdliner_eval.ml:34 (dune.exe+0xd28d05) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #11 camlCmdliner_eval.eval_value_inner_1700 vendor/cmdliner/src/cmdliner_eval.ml:202 (dune.exe+0xd2a584) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #12 camlMain.entry bin/main.ml:106 (dune.exe+0x5d9b29) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #13 caml_program <null> (dune.exe+0x5d15b9) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #14 caml_start_program <null> (dune.exe+0xe878c3) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #15 caml_startup_common runtime/startup_nat.c:132 (dune.exe+0xe87070) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #16 caml_startup_common runtime/startup_nat.c:88 (dune.exe+0xe87070)
    #17 caml_startup_exn runtime/startup_nat.c:139 (dune.exe+0xe87117) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)
    #18 caml_startup runtime/startup_nat.c:144 (dune.exe+0xe87117)
    #19 caml_main runtime/startup_nat.c:151 (dune.exe+0xe87117)
    #20 main runtime/main.c:37 (dune.exe+0x5cdbe5) (BuildId: 690605e4ac77a02bdcda3b1ee7b57cd7f73853b2)

SUMMARY: ThreadSanitizer: data race runtime/minor_gc.c:250 in oldify_one
==================
ThreadSanitizer: reported 1 warnings                
make: *** [Makefile:55: dev] Error 66

This seems to come from ocaml itself:

https://github.com/ocaml/ocaml/blob/5.2.0/otherlibs/unix/mkdir.c#L36-L38

jmid · 2024-05-21T18:36:50Z

Good catch! I initially found one in Sys.mkdir: https://github.com/ocaml/ocaml/blob/trunk/runtime/sys.c#L376

As discussed in ocaml#12737, using `Int_val` inside blocking sections can cause data races and is now seen as a bad idea. (this causes a TSAN warning when using Dune, see ocaml/dune#10554)

emillon · 2024-05-22T07:56:12Z

See ocaml/ocaml#13188

As discussed in ocaml#12737, using `Int_val` inside blocking sections can cause data races and is now seen as a bad idea. (this causes a TSAN warning when using Dune, see ocaml/dune#10554)

@jmid

Fixes ocaml#10553 Quoting @jmid, using a local variable without the runtime lock in place, is against the rules. For integer values, sometimes the rules are bent, but this is not a good idea. See ocaml/ocaml#12737. Signed-off-by: Etienne Millon <me@emillon.org>

@jmid

Fixes ocaml#10553 Quoting @jmid, using a local variable without the runtime lock in place, is against the rules. For integer values, sometimes the rules are bent, but this is not a good idea. See ocaml/ocaml#12737. Signed-off-by: Etienne Millon <me@emillon.org>

@jmid

Fixes #10553 Quoting @jmid, using a local variable without the runtime lock in place, is against the rules. For integer values, sometimes the rules are bent, but this is not a good idea. See ocaml/ocaml#12737. Signed-off-by: Etienne Millon <me@emillon.org>

@dbuenzli

CHANGES: ### Fixed - Fix interpretation of `exists_if` predicate in `META` files of installed libraries containing more than one element. (ocaml/dune#10564, fixes ocaml/dune#10563, @dbuenzli, @nojb) - Fix TSAN warning in wait4 stubs (ocaml/dune#10554, fixes ocaml/dune#10553, @emillon)

As discussed in ocaml#12737, using `Int_val` inside blocking sections can cause data races and is now seen as a bad idea. (this causes a TSAN warning when using Dune, see ocaml/dune#10554)

@jmid

Fixes ocaml#10553 Quoting @jmid, using a local variable without the runtime lock in place, is against the rules. For integer values, sometimes the rules are bent, but this is not a good idea. See ocaml/ocaml#12737. Signed-off-by: Etienne Millon <me@emillon.org>

@dbuenzli

CHANGES: ### Fixed - Fix interpretation of `exists_if` predicate in `META` files of installed libraries containing more than one element. (ocaml/dune#10564, fixes ocaml/dune#10563, @dbuenzli, @nojb) - Fix TSAN warning in wait4 stubs (ocaml/dune#10554, fixes ocaml/dune#10553, @emillon)

emillon force-pushed the tsan-wait4-pid branch from 196adda to eb84bc6 Compare May 21, 2024 15:08

OlivierNicole approved these changes May 21, 2024

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emillon mentioned this pull request May 22, 2024

unix: move Int_val outside blocking section ocaml/ocaml#13188

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Merge branch 'main' into tsan-wait4-pid

9f37dad

emillon merged commit f998110 into ocaml:main May 23, 2024
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emillon deleted the tsan-wait4-pid branch May 23, 2024 09:19

emillon mentioned this pull request May 24, 2024

3.15.3 release tracking #10566

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emillon mentioned this pull request May 24, 2024

[new release] dune (15 packages) (3.15.3) ocaml/opam-repository#25931

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fix(stdune): fix TSAN warning in wait4_stubs #10554

fix(stdune): fix TSAN warning in wait4_stubs #10554

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emillon commented May 22, 2024

fix(stdune): fix TSAN warning in wait4_stubs #10554

fix(stdune): fix TSAN warning in wait4_stubs #10554

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