https://bugs.freedesktop.org/show_bug.cgi?id=40423
--- Comment #25 from Benoit Jacob bjacob@mozilla.com 2011-10-06 04:54:06 PDT --- Thanks a lot.
https://bugzilla.mozilla.org/show_bug.cgi?id=691003 is fixed as of today, will be in tomorrow's Nightly.
It seems that this bug could have explained a lot of mysterious Firefox crashiness on linux. Having it fixed fills me with indescriptible glee.