On 6/16/26 5:01 AM, Alexei Starovoitov wrote: > 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().
Right, it only covers percpu sheaves locks. > VMs need to configured properly. Even nested VMs support > PERF_COUNT_HW_CPU_CYCLES. And now that even VMs that are not properly configured can test it using kprobe with _some_ coverage, we don't really need the fallback. Will drop the fallback. > 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. Will do. Thanks! -- Cheers, Harry / Hyeonggon
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