Re: kern/59339: heartbeat watchdog fires since 10.99.14

["Thomas Klausner via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR kern/59339; it has been noted by GNATS.

From: Thomas Klausner <wiz%NetBSD.org@localhost>
To: Taylor R Campbell <riastradh%NetBSD.org@localhost>
Cc: Patrick Welche <prlw1%welche.eu@localhost>, gnats-bugs%NetBSD.org@localhost
Subject: Re: kern/59339: heartbeat watchdog fires since 10.99.14
Date: Fri, 9 May 2025 10:55:03 +0200

 On Fri, May 09, 2025 at 12:03:52AM +0000, Taylor R Campbell wrote:
 > If you catch a core dump with a stack trace in itimer_transition, can
 > you print all the locals and parameters in gdb?
 > 
 > I believe this all started happening shortly after
 > https://mail-index.NetBSD.org/source-changes/2025/04/01/msg156191.html
 > and all the stack traces have been in callout processing, including
 > one in the itimer_transition subroutine which I rewrote in that
 > commit, so it's likely to be related.
 > 
 > My guess is that there's some itimer parameter, or bad timing, which
 > causes itimer_transition to do something foolish -- that or the
 > conversion from the next timeout as a timespec to a duration in ticks,
 > in tshztoup/tshzto, is going wrong.
 > 
 > Can you please try the attached patch to check for some possible types
 > of foolishness earlier?  If this confirms my hypothesis, it will turn
 > a silent lockup into a panic.
 
 A kernel with this patch paniced twice in 10 minutes.  I didn't even
 have time to start mutt and send an email after the first panic.
 
 crash says
 
 System panicked: kernel diagnostic assertion "ticks > 0" failed: file "/usr/src/sys/kern/kern_time.c", line 837 [0] it->it_time.it_value=1746779983.758601200 ticks=0
 
 and
 
 System panicked: kernel diagnostic assertion "ticks > 0" failed: file "/usr/src/sys/kern/kern_time.c", line 837 [0] it->it_time.it_value=1746780327.140798025 ticks=0
 
 Let me know what further information you need, or if you want me to
 upload the crash dumps & debug kernels somewhere.
  Thomas