Hi,
I've had the joy to debug a production system with a really crappy setup.
They have a user "fred" which belongs to ~5000 groups (say group1-group5000).
So far so bad. Even worse, they have a nfs backend with lots of files which are owned by users belonging to these groups.
Ok, now my problem is that "fred" can open a file which is
-rw-rw---- someone group300 foo
but a read on this file will fail with EIO
Since group300 is way beyond the 16 groups nfs supports shouldn't fred actually get a EACCES back from the open call?
Problem happens with 2.6.13 (vanilla, not tainted) on both server and client.