On Mon Jun 15, 2026 at 4:05 AM PDT, Harry Yoo (Oracle) wrote: > slub_kunit uses hardware perf events to invoke _nolock() APIs from NMI > context. However, creating a HW perf event fails when there is no > hardware PMU, or when running in a virtualized environment without a > virtual PMU configured. > > Since tests are often performed in virtualized environments, fall back > to a SW perf event so that the test can still run, even if it cannot > cover IRQ-disabled sections.
Frankly, I wouldn't bother with this fallback, since it completely misses irq disabled section which is the one to test with *_nolock(). VMs need to configured properly. Even nested VMs support PERF_COUNT_HW_CPU_CYCLES. Also in overflow_handler_test_nolock() I would add even->hw.interrupts = 0; to the end to make sure it actually stress tests things. Without it NMIs are not firing quickly enough.
