Valgrind detects a leak of 136 bytes (direct) with js::ArgumentsObject* js::ArgumentsObject::create on the stack, see attached snippet which comes from: https://tbpl.mozilla.org/php/getParsedLog.php?id=17064538&tree=Firefox&full=1 m-c changeset rev is a761bfc192b5. It didn't happen in the previous Valgrind run here: https://tbpl.mozilla.org/?noignore=1&jobname=valgrind&rev=dd68409d7810 So I'm guessing the regression range is: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=dd68409d7810&tochange=a761bfc192b5

Bug 809021 maybe? I can't tell if the arguments it talking about are the same as the arguments object...

A variant appeared in m-c d8be4bc4fba8 through https://tbpl.mozilla.org/php/getParsedLog.php?id=18854034&tree=Firefox&full=1 Checked in a suppression: http://hg.mozilla.org/mozilla-central/rev/ce9cdd801a73

gkw: Might this be related to Bug 829421 ? Apparently they had the same error reported on the gnome-shell. Strangely, this might be a valgrind error, because this would only happen in case of OOM.

Thanks, Nicolas! I've removed the suppression for this in https://hg.mozilla.org/mozilla-central/rev/425835f6a9e2 Assuming fixed by bug 829421.

Reopening. I still see this on 64-bit builds after removing the suppression, see bug 829421 comment 15 and 16. Suppression re-added by backing out suppression removal changeset: https://hg.mozilla.org/mozilla-central/rev/19f630648c80

This is no longer occurring in Valgrind-on-TBPL runs.