Created attachment 298572 [details]
Running the web app of wunderlist.com, after some time I got the tab frozen. Backtrace is attached
Created attachment 298573 [details]
The funny thing is that as I was reporting the bug the first time, while selecting components and priorities, that new tab got stuck too.
I forgot to say that Webkit was built against GNOME jhbuild of Jan 8th 2017, all master and the version was 2.15.2.
I think this is the same issue than bug 167688.
They are 2 bugs actually, one happening with DRI3 and another one with DRI2.
Something very similar to the DRI3 was reported here https://bugs.freedesktop.org/show_bug.cgi?id=84252
but it seems to be already fixed for versions of libxcb higher than 1.11-something (depending on the distro). Seems to be fixed in 1.11-8 in fedora and the debian versions 1-11-1 seems tho have the fix as well.
Regarding the DRI2, there's this one still open https://bugs.freedesktop.org/show_bug.cgi?id=94108 which is probably related.
I any case, it doesn't seem to be related to webkit, but some lower layer.
OK. Let's mark this as the duplicate, because there are better backtraces in bug #167688.
*** This bug has been marked as a duplicate of bug 167688 ***