checking stopevent 2!

Robert Watson rwatson at FreeBSD.ORG
Sat Nov 15 06:40:38 PST 2003


On Sat, 15 Nov 2003, Andy Farkas wrote:

> These messages spew onto my console and into syslogd once every second:

Heh.  Sounds like your box is having a really bad day, we'll see if we
can't get it fixed up over the next couple of weeks as things settle out
:-).

I think John has this one in his sights already, we talked about the
sigacts locking during the release engineering telecon yesterday (CC'd
gratuitously in this message).  Basically, every place where a debugger
can "stop" a process there's a call to STOPEVENT(), which may sleep
indefinitely waiting to be restarted by the process performing the
debugging.  The problem appears to be that recent changes pushed a
STOPEVENT() call inside code holding a mutex, so the locking of that piece
of code needs to be changed slightly to make sure that doesn't happen.  IT
would probably be useful if you could drop to DDB and generate a trace for
the event.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org      Network Associates Laboratories


> 
> ...
> Nov 15 16:05:44 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:44 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4656aa8) locked @ /hummer/src-current/src/sys/kern/kern_condvar.c:289
> Nov 15 16:05:44 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:44 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4656aa8) locked @ /hummer/src-current/src/sys/kern/subr_trap.c:260
> Nov 15 16:05:44 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:45 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4656aa8) locked @ /hummer/src-current/src/sys/kern/subr_trap.c:260
> Nov 15 16:05:45 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:45 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4663aa8) locked @ /hummer/src-current/src/sys/kern/kern_synch.c:293
> Nov 15 16:05:45 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:45 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4663aa8) locked @ /hummer/src-current/src/sys/kern/subr_trap.c:260
> Nov 15 16:05:45 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:45 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4663aa8) locked @ /hummer/src-current/src/sys/kern/subr_trap.c:260
> Nov 15 16:05:45 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:45 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4656aa8) locked @ /hummer/src-current/src/sys/kern/kern_condvar.c:289
> Nov 15 16:05:45 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:46 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4656aa8) locked @ /hummer/src-current/src/sys/kern/subr_trap.c:260
> Nov 15 16:05:46 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:46 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4656aa8) locked @ /hummer/src-current/src/sys/kern/kern_condvar.c:289
> Nov 15 16:05:46 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:46 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4656aa8) locked @ /hummer/src-current/src/sys/kern/subr_trap.c:260
> Nov 15 16:05:46 <kern.crit> hummer kernel: checking stopevent 2 with the following non-sleepable locks held:
> Nov 15 16:05:46 <kern.crit> hummer kernel: exclusive sleep mutex sigacts r = 0 (0xc4656aa8) locked @ /hummer/src-current/src/sys/kern/subr_trap.c:260
> ...
> 
> 
> 
> This is latest -current (cvsup'd a few hours ago)
> 
> 
> --
> 
>  :{ andyf at speednet.com.au
> 
>         Andy Farkas
>     System Administrator
>    Speednet Communications
>  http://www.speednet.com.au/
> 
> 
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