The following should print the traces when we hand over ENOMEM to the
caller. It should catch all charge paths (migration is not covered but
that one is not important here). If we don't see any traces from here
and there is still global OOM striking then there must be something else
to trigger this.
Could you test this with the patch which aims at fixing your deadlock,
please? I realise that this is a production environment but I do not see
anything relevant in the code.

Michal,

i think/hope this is what you wanted:
http://www.watchdog.sk/lkml/oom_mysqld2