My development system is Fedora 32. After update from kernel 5.8 to 5.9, programs being debugged segfault immediately after starting QThread.

The crash appears to be originating in the interaction between Qt creator and gdb.

The following code causes the crash (full project attached). The call to _thread.start() returns, but crashes prior to the onStart signal invocation (see attached screenshots).

#include "testservice.h"
#include <QDebug>

TestService::TestService()
{
    qDebug() << "Construct";

    connect(&_thread, &QThread::started, this, &TestService::onStarted);
    connect(&_timer, &QTimer::timeout, this, &TestService::onTimer);

    _timer.moveToThread(&_thread);
    moveToThread(&_thread);

    qDebug() << "Prior to _thread.start()";
    _thread.start();
    qDebug() << "After call to _thread.start()";
}

void TestService::onStarted()
{
    qDebug() << "Start";

    _timer.start(1000);
}

void TestService::onTimer()
{
    qDebug() << "Timer";
}

I first encountered the issue after last nights upgrade to 5.9.11-100.fc32.x86_64.

The previous working kernel is 5.8.18-200.fc32.x86_64

GCC Version

spunak@muadib:~/tmp$ gcc --version
gcc (GCC) 10.2.1 20201016 (Red Hat 10.2.1-6)

GDB Version

spunak@muadib:~/tmp$ gdb --version
GNU gdb (GDB) Fedora 9.1-6.fc32