IMA memory hog

They should get rid of the whole lookup thing and add the info to the inode.
If that would bloat the inode too much, perhaps give the inode a variable
size (size determined at startup), or add a pointer to the IMA struct. But
both seem too much complexity for no gain, just disable IMA except when
you're actually using it. And then adding the info to the inode saves more
memory because you don't have to keep around a whole extra tree. The IMA
menuconfig text needs updating of course.

As someone mentioned in the thread, things become simpler when IMA is only
enabled or disabled at boot time, so no need to keep track of writers etc.
when IMA is not used.