Re: [PATCH 2/2] RFC: soft/hardlookup: taint kernel

Sergey Senozhatsky
2019-05-09T09:24:49Z

On (05/02/19 21:42), Daniel Vetter wrote:
[..]
> @@ -469,6 +469,8 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
> add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
> if (softlockup_panic)
> panic("softlockup: hung tasks");
> + else
> + add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
> __this_cpu_write(soft_watchdog_warn, true);

Soft lockup sets TAINT_SOFTLOCKUP bit. Would it be enough for your CI?

[..]
> @@ -154,6 +154,8 @@ static void watchdog_overflow_callback(struct perf_event *event,
>
> if (hardlockup_panic)
> nmi_panic(regs, "Hard LOCKUP");
> + else
> + add_taint(TAINT_WARN, LOCKDEP_STILL_OK);

Maybe you can mirror what soft lockup does. Add a HARDLOCKUP taint bit

+++ b/include/linux/kernel.h
@@ -571,7 +571,8 @@ extern enum system_states {
#define TAINT_LIVEPATCH 15
#define TAINT_AUX 16
#define TAINT_RANDSTRUCT 17
-#define TAINT_FLAGS_COUNT 18
+#define TAINT_HARDLOCKUP 18
+#define TAINT_FLAGS_COUNT 19

and then set TAINT_HARDLOCKUP in watchdog_overflow_callback().

Just a small idea, I'll leave this to more experienced people.

-ss