Subject: Re: [PATCH v2] powerpc/watchdog: Use hrtimers for per-CPU heartbeat

From: Michael Ellerman <[email-masked]>
Date: Fri, 3 May 2019 16:59:19 +1000 (AEST)

On Tue, 2019-04-09 at 04:40:05 UTC, Nicholas Piggin wrote:
> Using a jiffies timer creates a dependency on the tick_do_timer_cpu
> incrementing jiffies. If that CPU has locked up and jiffies is not
> incrementing, the watchdog heartbeat timer for all CPUs stops and
> creates false positives and confusing warnings on local CPUs, and
> also causes the SMP detector to stop, so the root cause is never
> detected.
> 
> Fix this by using hrtimer based timers for the watchdog heartbeat,
> like the generic kernel hardlockup detector.
> 
> Cc: Gautham R. Shenoy <[email-masked]>
> Reported-by: Ravikumar Bangoria <[email-masked]>
> Signed-off-by: Nicholas Piggin <[email-masked]>
> Tested-by: Ravi Bangoria <[email-masked]>
> Reported-by: Ravi Bangoria <[email-masked]>
> Reviewed-by: Gautham R. Shenoy <[email-masked]>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/7ae3f6e130e8dc6188b59e3b4ebc2f16

cheers