selftests/mm: use pattern matching in .gitignore

The current .gitignore hardcodes each generated test binary by name,
requiring updates every time a new test is added.

Switch to the pattern-matching approach similar to KVM:selftests.  Ignore
everything by default and then allow source extensions (.c, .h, .sh) and
tracked non-source files.

Note that local_config.h was renamed to local_config.h_gen in a previous
patch so that un-ignoring *.h files does not cause generated build
artifacts to become untracked.

[akpm@linux-foundation.org: fix botched merge resolution]
Link: https://lore.kernel.org/20260803221732.3651981-3-pratmal@google.com
Signed-off-by: Pratyush Mallick <pratmal@google.com>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Suggested-by: Yosry Ahmed <yosry@kernel.org>
Reviewed-by: SJ Park <sj@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Liam R. Howlett" <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/.gitignore

@@ -1,68 +1,10 @@
 # SPDX-License-Identifier: GPL-2.0-only
-cow
-hugepage-mmap
-hugepage-mremap
-hugepage-shm
-hugepage-vmemmap
-hugetlb-mmap
-hugetlb-mremap
-hugetlb-shm
-hugetlb-vmemmap
-hugetlb-madvise
-hugetlb-read-hwpoison
-hugetlb-soft-offline
-khugepaged
-map_hugetlb
-map_populate
-thuge-gen
-compaction_test
-memory-failure
-migration
-mlock2-tests
-mrelease_test
-mremap_dontunmap
-mremap_test
-on-fault-limit
-transhuge-stress
-pagemap_ioctl
-pfnmap
-process_madv
-*.tmp*
-protection_keys
-protection_keys_32
-protection_keys_64
-madv_populate
-uffd-stress
-uffd-unit-tests
-uffd-wp-mremap
-mlock-intersect-test
-mlock-random-test
-virtual_address_range
-gup_test
-va_128TBswitch
-map_fixed_noreplace
-write_to_hugetlbfs
-hmm-tests
-memfd_secret
-soft-dirty
-split_huge_page_test
-ksm_tests
-local_config.h
-local_config.mk
-ksm_functional_tests
-mdwe_test
-gup_longterm
-mkdirty
-va_high_addr_switch
-hugetlb_fault_after_madv
-hugetlb_madv_vs_map
-mseal_test
-droppable
-hugetlb_dio
-pkey_sighandler_tests_32
-pkey_sighandler_tests_64
-guard-regions
-merge
-prctl_thp_disable
-rmap
-folio_split_race_test
+*
+!/**/
+!*.c
+!*.h
+!*.sh
+!.gitignore
+!Makefile
+!config
+!settings