I'm running Debian unstable with libX11-6 from experimental libX11-6: 1.1-6 libxcb1: 0.9.92-1 libxcb-xlib0: 0.9.92-1 I have a small python-qt application (frontend for tracker) which crashes whenever I close the app. The app receives a SIG 11 (SIGSEGV) reproducibely. To test the app, you need to have python-kde installed.
Created attachment 7963 [details] python-qt based tracker frontend
Created attachment 7964 [details] backtrace
Thanks for the CC, Josh. Michael, please let your Xlib bug reports go to xorg-team so I see them. :-) I'm not entirely sure, but I think this is a duplicate of bug 8947. I suspect that, like that case, Qt is calling XFreeCursor on an invalid Display. If so, that's an error in Qt, and it's surprising that it ever worked. Somebody should file a bug with Trolltech that they should be more careful in the QCursorData destructor. When the connection is closing down there's no need to call XFreeCursor, and if it closed due to an I/O error there's no opportunity to free the cursor anyway. *** This bug has been marked as a duplicate of 8947 ***
Sorry, Bugzilla didn't make it obvious that you *did* let this get assigned to xorg-team. Chalk that up to "Bugzilla sucks".
If it got closed due to an I/O error, I'd expect to see _XIOError in the backtrace, though.
(unless Python or SIP has done some unspeakable things to the stack, of course.)
I wasn't trying to say that the proximate cause was the same, only the root cause. The QCursorData destructor can't safely call XFreeCursor, whether the destructor was triggered by _XIOError's exit() call or by a normal shutdown. But if XCloseDisplay hasn't actually been called before XFreeCursor segfaults, then I'd take that as a sign that this isn't even the same root cause.
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