[dm-devel] [QUESTION] multipathd crash when stopping

[Martin Wilck]

On Tue, 2021-01-26 at 14:50 +0800, lixiaokeng wrote:
> When stopping multipathd (systemctl restart multipathd.service),
> there
> is a multipathd crash occasionally(not reproduced).

If this happens only during shutdown, it might be related to thread
cancellation. Can you try disabling cancellation for the
udev_monitor_receive_device() call?


    int oldstate;

    pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);

    udev_monitor_receive_device(...)

    pthread_setcancelstate(oldstate, NULL);
    pthread_testcancel();

In general, running multipathd under valgrind might help finding the
issue. 

But valgrind will slow down multipathd drastically, so timings will
change, and it's not granted that the problem will still be
reproducable. Alternatively, you can work with -fsanitize=address, but
in this specific case you'd need to compile libudev with this option,
too.

Martin