[Xcb] [Bug 27552] Lots of processes crash in XCreatePixmap() with _XAllocID: Assertion `ret != inval_id' failed

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Thu Apr 15 05:48:01 PDT 2010


--- Comment #2 from Martin Pitt <martin.pitt at ubuntu.com> 2010-04-15 05:48:01 PDT ---
(In reply to comment #1)
> It would be really nice to know where the last call to XIDAlloc was before the
> one that fails, and for that I'd love to have a minimal test case.

Indeed; I'm afraid I can't say more about this myself, but I asked for a
reproduction recipe on the downstream bug a few days ago. Once we have a way to
reproduce this, we can strip that down to a test case.

> Any chance these applications are using libX11 from more than one thread?

Some certainly do, but amongst the many duplicates are a lot of progams which
are single-threaded; for example services-admin (from gnome-system-tools,
LP#432122) or gigolo (LP#468544)

> It looks like a fair number of the reported stack traces are
> single-threaded, making that an unlikely explanation for those reports. :-)
> It's possible there are two separate bugs here, I suppose...

Possibly. It seems that about half of the reports are in gnome-panel and
firefox, but since they are also much more popular than the apps mentioned
above that kind of bias is expected.

> In lieu of a minimal test, perhaps you can tell me which X extensions these
> applications have in common? Perhaps the client library for some extension
> allocates an XID but is missing a SyncHandle call; if the next X request also
> tries to allocate an XID you'd get this assertion failure.

The bugs unfortunately don't have Xorg logs, but I don't think that they will
differ that much between different installations. I searched Launchpad for a
few Xorg logs for various drivers, and in fact for a given graphics driver the
extension lists were exactly identical (I took samples of about 5 per driver):

common for intel, ati, fglrx, nvidia: MIT-SCREEN-SAVER XFree86-VidModeExtension
XFree86-DGA DPMS XVideo XVideo-MotionCompensation X-Resource DOUBLE-BUFFER GLX

suppose those are uninteresting)

I asked in the downstram bug for a few Xorg logs from those people who can
reproduce the crash. Perhaps it will turn out that they are all using the same
graphics driver.

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