selftests/mm/guard-regions: skip collapse test when thp not enabled

Patch series "selftests/mm: skip several tests when thp is not available",
v8.

There are several tests requires transprarent hugepages, when run on thp
disabled kernel such as realtime kernel, there will be false negative.
Mark those tests as skip when thp is not available.


This patch (of 6):

When thp is not available, just skip the collape tests to avoid the false
negative.

Without the change, run with a thp disabled kernel:
./run_vmtests.sh -t madv_guard -n 1
<snip/>
# RUN guard_regions.anon.collapse ...
# guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
# collapse: Test terminated by assertion
# FAIL guard_regions.anon.collapse
not ok 2 guard_regions.anon.collapse
<snip/>
# RUN guard_regions.shmem.collapse ...
# guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
# collapse: Test terminated by assertion
# FAIL guard_regions.shmem.collapse
not ok 32 guard_regions.shmem.collapse
<snip/>
# RUN guard_regions.file.collapse ...
# guard-regions.c:2217:collapse:Expected madvise(ptr, size, MADV_NOHUGEPAGE) (-1) == 0 (0)
# collapse: Test terminated by assertion
# FAIL guard_regions.file.collapse
not ok 62 guard_regions.file.collapse
<snip/>
# FAILED: 87 / 90 tests passed.
# 17 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
# Totals: pass:70 fail:3 xfail:0 xpass:0 skip:17 error:0

With this change, run with thp disabled kernel:
./run_vmtests.sh -t madv_guard -n 1
<snip/>
# RUN guard_regions.anon.collapse ...
# SKIP Transparent Hugepages not available
# OK guard_regions.anon.collapse
ok 2 guard_regions.anon.collapse # SKIP Transparent Hugepages not available
<snip/>
# RUN guard_regions.file.collapse ...
# SKIP Transparent Hugepages not available
# OK guard_regions.file.collapse
ok 62 guard_regions.file.collapse # SKIP Transparent Hugepages not available
<snip/>
# RUN guard_regions.shmem.collapse ...
# SKIP Transparent Hugepages not available
# OK guard_regions.shmem.collapse
ok 32 guard_regions.shmem.collapse # SKIP Transparent Hugepages not available
<snip/>
# PASSED: 90 / 90 tests passed.
# 20 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
# Totals: pass:70 fail:0 xfail:0 xpass:0 skip:20 error:0

Link: https://lore.kernel.org/20260402014543.1671131-1-chuhu@redhat.com
Link: https://lore.kernel.org/20260402014543.1671131-2-chuhu@redhat.com
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Li Wang <liwang@redhat.com>
Cc: Nico Pache <npache@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>