Re: reboot -r no longer reboots FreeBSD-CURRENT

From: Konstantin Belousov <kostikbel_at_gmail.com>
Date: Fri, 10 Jul 2026 16:17:11 UTC 
On Fri, Jul 10, 2026 at 11:58:01AM -0400, Mark Johnston wrote:
> On Thu, Jul 09, 2026 at 09:51:40PM +0100, Graham Perrin wrote:
> > Screenshot etc. at
> > <https://mastodon.bsd.cafe/@grahamperrin/116814858405640533>
> 
> This seems to be a regression from commit 24d887436dcd5b6c18a7505e477c79cae3002c3a.

Well, 'the regression from' is probably not exact formulation.
I do not think that correct code should change to cause SIGSEGV
due to dynamic linkage.

> I'm not sure exactly why, but after running "reboot -r", init(8) does
> something to trigger SIGSEGV, and the kernel appears to hang delivering
> the signal in a loop.  In particular, init(8) registers a SIGSEGV
> handler.

If you set sysctl machdep.uprintf_signal to 1, does kernel emit anything
on this occurance?  If yes, perhaps take the 'procstat vm 1' before
triggering the reboot, so that we can at least infer the module and
source line that caused the SIGSEGV.


> 
> This breaks the EC2 builder images, which rely on reboot -r during boot,
> but I can easily reproduce it in a VM.