On Tue, 14 Dec 2021 at 09:38, Zhouyi Zhou <zhouzhouyi@xxxxxxxxx> wrote: [...] > 2) The KCSAN kernel compile with clang-12: > CONFIG_HAVE_ARCH_KCSAN=y > CONFIG_HAVE_KCSAN_COMPILER=y > CONFIG_KCSAN=y > CONFIG_KCSAN_SELFTEST=y > # CONFIG_KCSAN_EARLY_ENABLE is not set > CONFIG_KCSAN_NUM_WATCHPOINTS=64 > CONFIG_KCSAN_UDELAY_TASK=80 > CONFIG_KCSAN_UDELAY_INTERRUPT=20 > CONFIG_KCSAN_DELAY_RANDOMIZE=y > CONFIG_KCSAN_SKIP_WATCH=4000 > CONFIG_KCSAN_SKIP_WATCH_RANDOMIZE=y > # CONFIG_KCSAN_INTERRUPT_WATCHER is not set > CONFIG_KCSAN_REPORT_ONCE_IN_MS=3000 > # CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN is not set > # CONFIG_KCSAN_STRICT is not set > CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=y > # CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC is not set > CONFIG_KCSAN_IGNORE_ATOMICS=y > CONFIG_KCSAN_PERMISSIVE=y Note, rcutorture selects CONFIG_KCSAN_STRICT=y, which may be one part of the issue. The other is that the -rcu tree has KCSAN enhancements not yet available in mainline, which are enabled together with CONFIG_KCSAN_STRICT, and make KCSAN slightly more aggressive (i.e. finds data races faster) as well. Although you can also locally make KCSAN a bit more aggressive by lowering CONFIG_KCSAN_SKIP_WATCH (boot param kcsan.skip_watch=), to e.g. 2000-3000, but too low and you'll hurt forward-progress. -- Marco
