Subject: linux-next: build failure after merge of the mm-nonmm-unstable tree

From: Mark Brown <[email-masked]>
Date: Tue, 17 Mar 2026 14:32:51 +0000

Hi all,

After merging the mm-unstable tree, today's linux-next build (arm64
kunit) failed like this:

[13:30:42] # hpcc_test_compare_value_boundaries: EXPECTATION FAILED at lib/tests/percpu_counter_tree_kunit.c:157
[13:30:42] Expected 1 == percpu_counter_tree_precise_compare_value(&pct, (long)under), but
[13:30:42]     percpu_counter_tree_precise_compare_value(&pct, (long)under) == 0 (0x0)
[13:30:42] # hpcc_test_compare_value_boundaries: EXPECTATION FAILED at lib/tests/percpu_counter_tree_kunit.c:160
[13:30:42] Expected -1 == percpu_counter_tree_precise_compare_value(&pct, -(long)over), but
[13:30:42]     percpu_counter_tree_precise_compare_value(&pct, -(long)over) == 0 (0x0)
[13:30:42] [FAILED] hpcc_test_compare_value_boundaries
[13:30:42] # hpcc_test_compare_counter_boundaries: EXPECTATION FAILED at lib/tests/percpu_counter_tree_kunit.c:246
[13:30:42] Expected 1 == percpu_counter_tree_precise_compare(&pct[0], &pct[1]), but
[13:30:42]     percpu_counter_tree_precise_compare(&pct[0], &pct[1]) == 0 (0x0)
[13:30:42] # hpcc_test_compare_counter_boundaries: EXPECTATION FAILED at lib/tests/percpu_counter_tree_kunit.c:251
[13:30:42] Expected -1 == percpu_counter_tree_precise_compare(&pct[0], &pct[1]), but
[13:30:42]     percpu_counter_tree_precise_compare(&pct[0], &pct[1]) == 0 (0x0)
[13:30:42] [FAILED] hpcc_test_compare_counter_boundaries
[13:30:42] [PASSED] hpcc_test_init_one
[13:30:42] [PASSED] hpcc_test_set
[13:30:42]     # module: percpu_counter_tree_kunit
[13:30:42] # percpu_counter_tree: pass:8 fail:2 skip:0 total:10

...

[13:30:47] Testing complete. Ran 9088 tests: passed: 9015, failed: 2, skipped: 71
[13:30:47] Failures: percpu_counter_tree.hpcc_test_compare_value_boundaries, percpu_counter_tree.hpcc_test_compare_counter_boundaries

Triggered by commit

  ebc1ff504f557 (lib: add kunit boundary tests for percpu_counter_tree comparisons)

though as it's a newly added test it's obviously entirely plausible that
it's flagging an existing bug.  I used the tree from next-20260316
instead.