I ran into some bugs testing epoll in ia32-emulation mode on ia64.
The attached patch fixes the problems and is well tested.
Here is a summary of the changes:

Changes to sys32_epoll_ctl() and sys32_epoll_wait():
- changed epoll_event32.data to an array (this is subjective, but seems
to make the code more readable)

Changes to sys32_epoll_wait():
- added call to __get_free_pages if kmalloc(epoll_event array) fails.  This
  provides needed scalability and fixes the -ENOMEM failure during
epoll-pipetest.
- deleted copy-in of epoll_event array since this is not a user-inputsyscall
- changed to check numevents > 0 as indicator of success on call to
  sys_epoll_wait.
- changed to loop on numevents not maxevents when copying out to userspace.