generic/211: completely remove obsolete test and related code

generic/211: completely remove obsolete test and related code

This was a regression test for a bug in fs/aio.c kernel code that could
cause kernel crashing and was fixed in commit 3e45a10919b3 ("aio: remove
incorrect initialization of "nr_pages"") more than 20 years ago (in
v2.6.10).

The test code was basically trying to trigger the bug by doing repeated
mmaps until it would exhaust the vm.max_map_count limit, after which the
aio_setup_ring() would fail its own internal mmap and branch into
aio_free_ring() where it would attempt to free pages that were not
allocated and crash the kernel.

The bug is was not really relevant to filesystems in the first place,
and further to its fix it was made not possible to trigger due to commit
3dc9acb67600 ("aio: clean up and fix aio_setup_ring page mapping").

The test currently triggers the oom killer on systems where the
vm.max_map_count limit has been increased significantly from the default
as it eventually exhausts the available memory. This could be trivially
fixed by lowering and then restoring the limit just for the duration of
the test, but since it no longer serves any purpose let's drop it
completely.

Signed-off-by: Anthony Iliopoulos <ailiop@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zorro Lang <zlang@kernel.org>