Data race involving SharedGroup and encrypted file mappings

[finnschiermer]

@finnschiermer commented on Mon Mar 25 2019

Reported by the thread sanitizer.

../test/test_async_open.cpp:1957: Begin AsyncOpen_EncryptedServer
==================
WARNING: ThreadSanitizer: data race (pid=23492)
  Read of size 1 at 0x7fa471826017 by thread T16 (mutexes: write M913803392290289048, write M944488891067400320):
    #0 realm::SlabAlloc::get_committed_file_format_version() const ../src/realm/alloc_slab.cpp:748 (realm-sync-tests+0xa0cb7e)
    #1 realm::SharedGroup::do_open(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, bool, realm::SharedGroupOptions) ../src/realm/group_shared.cpp:1064 (realm-sync-tests+0xbd1512)
    #2 realm::SharedGroup::open(realm::Replication&, realm::SharedGroupOptions) /home/finn/sync/realm-core/src/realm/group_shared.hpp:871 (realm-sync-tests+0x244931)
    #3 realm::SharedGroup::SharedGroup(realm::Replication&, realm::SharedGroupOptions) /home/finn/sync/realm-core/src/realm/group_shared.hpp:844 (realm-sync-tests+0x244931)
    #4 realm::_impl::state_realm::StateRealms::get_latest_server_version(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) ../src/realm/noinst/state_realm.cpp:669 (realm-sync-tests+0x85a22f)
    #5 realm::_impl::state_realm::StateRealms::get_compactable_server_version(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) ../src/realm/noinst/state_realm.cpp:58 (realm-sync-tests+0x85a5ca)
    #6 get_state_realm_compactable_server_version ../src/realm/sync/server.cpp:1263 (realm-sync-tests+0x7f08cc)
    #7 get_max_compactable_server_version ../src/realm/sync/server.cpp:6988 (realm-sync-tests+0x7f08cc)
    #8 worker_integrate_changes_from_downstream ../src/realm/sync/server.cpp:5956 (realm-sync-tests+0x7f08cc)
    #9 worker_process_work_unit ../src/realm/sync/server.cpp:5368 (realm-sync-tests+0x7f268e)
    #10 run ../src/realm/sync/server.cpp:7108 (realm-sync-tests+0x7f4f9c)
    #11 operator() ../src/realm/util/thread_exec_guard.hpp:300 (realm-sync-tests+0x7f4f9c)
    #12 entry_point<realm::util::ThreadExecGuardWithParent<R, P>::State::start(const string*) [with R = (anonymous namespace)::Worker; P = (anonymous namespace)::ServerImpl]::<lambda()> > /home/finn/sync/realm-core/src/realm/util/thread.hpp:442 (realm-sync-tests+0x7f4f9c)
    #13 <null> <null> (libtsan.so.0+0x296bd)

  Previous write of size 8 at 0x7fa471826010 by thread T20 (mutexes: write M346):
    #0 mmap <null> (libtsan.so.0+0x533a0)
    #1 realm::util::EncryptedFileMapping::reclaim_page(unsigned long) ../src/realm/util/encrypted_file_mapping.cpp:593 (realm-sync-tests+0xda8836)
    #2 operator() ../src/realm/util/encrypted_file_mapping.cpp:630 (realm-sync-tests+0xda900e)
    #3 realm::util::EncryptedFileMapping::reclaim_untouched(unsigned long&, unsigned long&) ../src/realm/util/encrypted_file_mapping.cpp:669 (realm-sync-tests+0xda900e)
    #4 realm::util::reclaim_pages_for_file(realm::util::SharedFileInfo&, unsigned long&) ../src/realm/util/file_mapper.cpp:356 (realm-sync-tests+0xdb43cb)
    #5 realm::util::reclaim_pages() ../src/realm/util/file_mapper.cpp:408 (realm-sync-tests+0xdb4981)
    #6 realm::util::reclaimer_loop() ../src/realm/util/file_mapper.cpp:422 (realm-sync-tests+0xdb4e0c)
    #7 void std::__invoke_impl<void, void (*)()>(std::__invoke_other, void (*&&)()) /usr/include/c++/7/bits/invoke.h:60 (realm-sync-tests+0xdb9f89)
    #8 std::__invoke_result<void (*)()>::type std::__invoke<void (*)()>(void (*&&)()) /usr/include/c++/7/bits/invoke.h:95 (realm-sync-tests+0xdb9f89)
    #9 decltype (__invoke((_S_declval<0ul>)())) std::thread::_Invoker<std::tuple<void (*)()> >::_M_invoke<0ul>(std::_Index_tuple<0ul>) /usr/include/c++/7/thread:234 (realm-sync-tests+0xdb9f89)
    #10 std::thread::_Invoker<std::tuple<void (*)()> >::operator()() /usr/include/c++/7/thread:243 (realm-sync-tests+0xdb9f89)
    #11 std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (*)()> > >::_M_run() /usr/include/c++/7/thread:186 (realm-sync-tests+0xdb9f89)
    #12 <null> <null> (libstdc++.so.6+0xbd57e)

  Mutex M913803392290289048 is already destroyed.

  Mutex M944488891067400320 is already destroyed.

  Mutex M346 (0x7b0c00001e90) created at:
    #0 pthread_mutex_init <null> (libtsan.so.0+0x2c5bd)
    #1 realm::util::Mutex::init_as_regular() ../src/realm/util/thread.hpp:476 (realm-sync-tests+0x1e8fea)
    #2 realm::util::Mutex::Mutex() ../src/realm/util/thread.hpp:453 (realm-sync-tests+0x1e8fea)
    #3 __static_initialization_and_destruction_0 ../src/realm/util/file_mapper.cpp:109 (realm-sync-tests+0x1e8fea)
    #4 _GLOBAL__sub_I_file_mapper.cpp ../src/realm/util/file_mapper.cpp:861 (realm-sync-tests+0x1e8fea)
    #5 __libc_csu_init <null> (realm-sync-tests+0xe0c49c)

  Thread T16 'worker' (tid=23707, running) created by thread T2 at:
    #0 pthread_create <null> (libtsan.so.0+0x2bcfe)
    #1 realm::util::Thread::start(void* (*)(void*), void*) /home/finn/sync/realm-core/src/realm/util/thread.hpp:431 (realm-sync-tests+0x7e3df4)
    #2 start<realm::util::ThreadExecGuardWithParent<R, P>::State::start(const string*) [with R = (anonymous namespace)::Worker; P = (anonymous namespace)::ServerImpl]::<lambda()> > /home/finn/sync/realm-core/src/realm/util/thread.hpp:409 (realm-sync-tests+0x7e3df4)
    #3 start ../src/realm/util/thread_exec_guard.hpp:307 (realm-sync-tests+0x7e3df4)
    #4 start_with_signals_blocked ../src/realm/util/thread_exec_guard.hpp:264 (realm-sync-tests+0x7e3df4)
    #5 run ../src/realm/sync/server.cpp:7565 (realm-sync-tests+0x7e3df4)
    #6 realm::sync::Server::run() ../src/realm/sync/server.cpp:8976 (realm-sync-tests+0x7e41fd)
    #7 realm::fixtures::MultiClientServerFixture::run_server(int) ../test/sync_fixtures.hpp:988 (realm-sync-tests+0x265b1b)
    #8 realm::fixtures::MultiClientServerFixture::start()::{lambda()#1}::operator()() const ../test/sync_fixtures.hpp:755 (realm-sync-tests+0x265b1b)
    #9 realm::test_util::ThreadWrapper::Runner<realm::fixtures::MultiClientServerFixture::start()::{lambda()#1}>::run({lambda()#1}, realm::test_util::ThreadWrapper*) ../test/util/thread_wrapper.hpp:83 (realm-sync-tests+0x265b1b)
    #10 realm::test_util::ThreadWrapper::start<realm::fixtures::MultiClientServerFixture::start()::{lambda()#1}>(realm::fixtures::MultiClientServerFixture::start()::{lambda()#1} const&)::{lambda()#1}::operator()() const ../test/util/thread_wrapper.hpp:40 (realm-sync-tests+0x265b1b)
    #11 void* realm::util::Thread::entry_point<realm::test_util::ThreadWrapper::start<realm::fixtures::MultiClientServerFixture::start()::{lambda()#1}>(realm::fixtures::MultiClientServerFixture::start()::{lambda()#1} const&)::{lambda()#1}>({lambda()#1}) /home/finn/sync/realm-core/src/realm/util/thread.hpp:442 (realm-sync-tests+0x265b1b)
    #12 <null> <null> (libtsan.so.0+0x296bd)

  Thread T20 (tid=23690, running) created by thread T6 at:
    #0 pthread_create <null> (libtsan.so.0+0x2bcfe)
    #1 std::thread::_M_start_thread(std::unique_ptr<std::thread::_State, std::default_delete<std::thread::_State> >, void (*)()) <null> (libstdc++.so.6+0xbd834)
    #2 realm::SlabAlloc::note_reader_start(void*) ../src/realm/alloc_slab.cpp:1069 (realm-sync-tests+0xa0cd2c)
    #3 realm::SharedGroup::do_begin_read(realm::VersionID, bool) ../src/realm/group_shared.cpp:2041 (realm-sync-tests+0xbcb720)
    #4 realm::SharedGroup::begin_write() ../src/realm/group_shared.cpp:1902 (realm-sync-tests+0xbcba2e)
    #5 realm::WriteTransaction::WriteTransaction(realm::SharedGroup&) /home/finn/sync/realm-core/src/realm/group_shared.hpp:763 (realm-sync-tests+0x77d228)
    #6 realm::_impl::ClientStateDownload::initialize_from_new() ../src/realm/noinst/client_state_download.cpp:222 (realm-sync-tests+0x77d228)
    #7 realm::_impl::ClientStateDownload::initialize() ../src/realm/noinst/client_state_download.cpp:191 (realm-sync-tests+0x77fa1a)
    #8 realm::_impl::ClientStateDownload::ClientStateDownload(realm::util::Logger&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, realm::util::Optional<std::array<char, 64ul> >) ../src/realm/noinst/client_state_download.cpp:78 (realm-sync-tests+0x77ffbe)
    #9 realm::_impl::ClientImplBase::Session::activate() ../src/realm/noinst/client_impl_base.cpp:1821 (realm-sync-tests+0x76bd9b)
    #10 realm::_impl::ClientImplBase::Connection::activate_session(std::unique_ptr<realm::_impl::ClientImplBase::Session, std::default_delete<realm::_impl::ClientImplBase::Session> >) ../src/realm/noinst/client_impl_base.cpp:144 (realm-sync-tests+0x76ee7d)
    #11 actualize ../src/realm/sync/client.cpp:1427 (realm-sync-tests+0x6d09cc)
    #12 actualize_and_finalize_session_wrappers ../src/realm/sync/client.cpp:819 (realm-sync-tests+0x6d09cc)
    #13 operator() ../src/realm/sync/client.cpp:595 (realm-sync-tests+0x6d1f8e)
    #14 recycle_and_execute ../src/realm/util/network.hpp:3631 (realm-sync-tests+0x6d1f8e)
    #15 realm::util::network::Service::Impl::execute(std::unique_ptr<realm::util::network::Service::AsyncOper, realm::util::network::Service::LendersOperDeleter>&) ../src/realm/util/network.cpp:1647 (realm-sync-tests+0x690834)
    #16 realm::util::network::Service::Impl::run() ../src/realm/util/network.cpp:1407 (realm-sync-tests+0x690834)
    #17 realm::util::network::Service::run() ../src/realm/util/network.cpp:1776 (realm-sync-tests+0x690834)
    #18 realm::_impl::ClientImplBase::run() ../src/realm/noinst/client_impl_base.hpp:1143 (realm-sync-tests+0x6c23d1)
    #19 realm::sync::Client::run() ../src/realm/sync/client.cpp:1896 (realm-sync-tests+0x6c23d1)
    #20 realm::fixtures::MultiClientServerFixture::run_client(int) ../test/sync_fixtures.hpp:1020 (realm-sync-tests+0x265f59)
    #21 realm::fixtures::MultiClientServerFixture::start()::{lambda()#2}::operator()() const ../test/sync_fixtures.hpp:757 (realm-sync-tests+0x265f59)
    #22 realm::test_util::ThreadWrapper::Runner<realm::fixtures::MultiClientServerFixture::start()::{lambda()#2}>::run({lambda()#2}, realm::test_util::ThreadWrapper*) ../test/util/thread_wrapper.hpp:83 (realm-sync-tests+0x265f59)
    #23 realm::test_util::ThreadWrapper::start<realm::fixtures::MultiClientServerFixture::start()::{lambda()#2}>(realm::fixtures::MultiClientServerFixture::start()::{lambda()#2} const&)::{lambda()#1}::operator()() const ../test/util/thread_wrapper.hpp:40 (realm-sync-tests+0x265f59)
    #24 void* realm::util::Thread::entry_point<realm::test_util::ThreadWrapper::start<realm::fixtures::MultiClientServerFixture::start()::{lambda()#2}>(realm::fixtures::MultiClientServerFixture::start()::{lambda()#2} const&)::{lambda()#1}>({lambda()#1}) /home/finn/sync/realm-core/src/realm/util/thread.hpp:442 (realm-sync-tests+0x265f59)
    #25 <null> <null> (libtsan.so.0+0x296bd)

SUMMARY: ThreadSanitizer: data race ../src/realm/alloc_slab.cpp:748 in realm::SlabAlloc::get_committed_file_format_version() const
==================

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@realm-probot[bot] commented on Tue Mar 26 2019

Hey - looks like you forgot to add a T:* label - could you please add one?

[finnschiermer]

Fixed by #3270