[PATCH v3 RESEND 0/2] selftests/mm: Validate selections and scope memfd_secret setup

[Tianyi Chen]

run_vmtests.sh can reach test setup after invalid options or category
selections. Its memfd_secret preparation can also change ptrace_scope
when that category was not selected.

Patch 1 rejects invalid selections before setup, using the category list
in usage(). Patch 2 gates memfd_secret preparation on category selection
and executable presence.

I am resending from my Gmail address after delivery problems with my
previous address. I could not confirm delivery of the earlier v3 posting.
This series is rebased onto current mm-unstable; both patches are unchanged
from v3 according to range-diff. Neither fix is present in current
mm-unstable, mm-stable or mainline.

Changes in v3:
- Initialize VM_SELFTEST_ITEMS to "default" before getopts, as David
  suggested. Only -t changes the selection.
- Use Assisted-by: LLM in both patches.
- Add David's Acked-by to patch 2, whose code is unchanged from v2.

Validation after rebasing:
- Bash syntax, whitespace and checkpatch checks passed.
- Ten invalid option/category invocations and help passed before setup.
- Rebuilt the four focused test binaries and ran the rebased script in an
  x86-64 KVM guest. mmap, memfd_secret, combined selections, tab/newline
  separators and repeated -t with the final selection taking effect all
  passed.
- The guest lacks Yama. The ptrace_scope write condition was checked with
  a disposable file at the expected path, not Yama policy enforcement.

This is focused validation, not a run of the complete MM selftest suite.

v2: https://lore.kernel.org/r/178886112560.138404.1278745290043112298.mm-cli-v2-0@xxxxxxxxx

Tianyi Chen (2):
  selftests/mm: Reject invalid test selections before running tests
  selftests/mm: Only prepare ptrace_scope when memfd_secret is selected