kern/59679: Multiple "heart stopped beating" / "softints stuck for 16 seconds" panics

[abs%absd.org@localhost]

>Number:         59679
>Category:       kern
>Synopsis:       Multiple "heart stopped beating" / "softints stuck for 16 seconds" panics
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Sep 30 12:00:00 +0000 2025
>Originator:     David Brownlee
>Release:        11.0_BETA
>Organization:
>Environment:
NetBSD forsaken.absd.org 11.0_BETA NetBSD 11.0_BETA (GENERIC) #0: Wed Sep 24 12:39:13 UTC 2025  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64

>Description:
Since running netbsd-11 (beta) on a ThinkPad T14 have had 29 panics with "heart stopped beating" or "softints stuck for 16 seconds"

One of them has a "urtwn0: transmit failed, IOERROR" just before the panic, but the other 28 do not

A recent sample from mkrepro: NetBSD 11.0_BETA (GENERIC) #0: Wed Sep 24 12:39:13 UTC 2025

[   497.200735] /usr/pkg/bin/lxqt-panel: Unknown elf note type 1951465473 (unknown tag): [namesz=12, descsz=66 name=qt-project! ]
[   513.000735] cpu2: found cpu3 heart stopped beating after 16 seconds
[   513.000735] panic: cpu3[103 softclk/3]: heart stopped beating
[   513.000735] cpu3: Begin traceback...
[   513.000735] vpanic() at netbsd:vpanic+0x171
[   513.000735] panic() at netbsd:panic+0x3c
[   513.000735] defibrillator() at netbsd:defibrillator+0x6b
[   513.000735] ipi_msg_cpu_handler() at netbsd:ipi_msg_cpu_handler+0x68
[   513.000735] ipi_cpu_handler() at netbsd:ipi_cpu_handler+0xa2
[   513.000735] x86_ipi_handler() at netbsd:x86_ipi_handler+0x71
[   513.000735] Xresume_lapic_ipi() at netbsd:Xresume_lapic_ipi+0x18
[   513.000735] --- interrupt ---
[   513.000735] mutex_spin_enter() at netbsd:mutex_spin_enter+0x3b
[   513.000735] callout_softclock() at netbsd:callout_softclock+0xd9
[   513.000735] softint_dispatch() at netbsd:softint_dispatch+0x112
[   513.010735] DDB lost frame for netbsd:Xsoftintr+0x4c, trying 0xffffa98db843c0f0
[   513.010735] Xsoftintr() at netbsd:Xsoftintr+0x4c
[   513.010735] --- interrupt ---
[   513.010735] 788332d1a6748f3e:
[   513.010735] cpu3: End traceback...

These appear to be more likely when using an external monitor connected via a USB hub, and most likely on initial login to x11 but have occurred without any external monitor (USB or HDMI)

I've been tracking the releng builds and have crashdumps and kernels to match
>How-To-Repeat:
Boot NetBSD-11 beta on a ThinkPad T14 frequently. Profit most of the time, watch panic with sad face sometimes
>Fix: