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

[Martin Wilck]

On Thu, 2021-01-28 at 21:17 +0800, lixiaokeng wrote:
> 
> > > 
> > >    Thanks very much. Your suggestions is very helpful.
> > >    The problem reproduced and the bug seems that shown in
> > > https://bugzilla.redhat.com/show_bug.cgi?id=1293594.
> > 
> > Really? I don't see a connection to your case there. It's about
> > glusterfs and libgcc...
> > 
> > Martin
> > 
> > 
> Hi Martin:
> 
>     Change code as your suggestion, multipathd crash happens easly.
> Stack:
> #0  0x0000ffffb6118f4c in aarch64_fallback_frame_state
> (context=0xffffb523f200, context=0xffffb523f200, fs=0xffffb523e700)
> at ./md-unwind-support.h:74
> #1  uw_frame_state_for (context=context at entry=0xffffb523f200, 
> fs=fs at entry=0xffffb523e700) at ../../../libgcc/unwind-dw2.c:1257
> #2  0x0000ffffb6119ef4 in _Unwind_ForcedUnwind_Phase2
> (exc=exc at entry=0xffffb52403b0, context=context at entry=0xffffb523f200)
> at ../../../libgcc/unwind.inc:155
> #3  0x0000ffffb611a284 in _Unwind_ForcedUnwind (exc=0xffffb52403b0, 
> stop=stop at entry=0xffffb64846c0 <unwind_stop>,
> stop_argument=0xffffb523f630) at ../../../libgcc/unwind.inc:207
> #4  0x0000ffffb6484860 in __GI___pthread_unwind (buf=<optimized out>)
> at unwind.c:121
> #5  0x0000ffffb6482d08 in __do_cancel () at pthreadP.h:304
> #6  __GI___pthread_testcancel () at pthread_testcancel.c:26
> #7  0x0000ffffb5c528e8 in ?? ()
> 
> This issue seems being different from that I described firstly.
> Do you think they are related?

Yes. The thread crashes when it's cancelled. I think we have a problem
in a cleanup handler that we installed with pthread_cleanup_push().


> Will udev_device_unref lead to double free about first issue?

Any double free could cause it if it happens in a pthread cleanup
handler (iow, if we free something in the cleanup handler that had
been freed already).

What code base exactly were you using?

Martin