Date: Wed, 21 May 2003 10:41:30 -0300 From: "Daniel C. Sobral" <dcs@tcoip.com.br> To: Julian Elischer <julian@elischer.org> Cc: CURRENT <freebsd-current@FreeBSD.ORG> Subject: Re: /dev/null and KSE panic 100% reproducible Message-ID: <3ECB820A.1030507@tcoip.com.br> In-Reply-To: <Pine.BSF.4.21.0305201125490.22764-100000@InterJet.elischer.org> References: <Pine.BSF.4.21.0305201125490.22764-100000@InterJet.elischer.org>
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Julian Elischer wrote:
>
> the stack trace you showed is in the context of a clock interrupt,
> (or at least, SOME interrupt). The possibility is that the clock
> interrupt is recalculating priorities but somehow it's happenning when
> the system is already messing up it's scheduling data..
>
> Someone put the following code into kern/kern_switch.c
> /*
> * Only allow non system threads to run in panic
> * if they are the one we are tracing. (I think.. [JRE])
> */
> if (panicstr && ((td->td_proc->p_flag & P_SYSTEM) == 0 &&
> (td->td_flags & TDF_INPANIC) == 0))
> goto retry;
>
>
> It has the effect of throwing away threads that it has taken off teh run
> queue if we are in a panic.
>
> at a later time anything that goes through these threads will assume
> they are still on teh run queue and panic becasue they are not..
>
> try the following:
>
> change it to:
>
> if (panicstr && ((td->td_proc->p_flag & P_SYSTEM) == 0 &&
> (td->td_flags & TDF_INPANIC) == 0)) {
> /* note that it is no longer on the run queue */
> TD_SET_CAN_RUN(td);
> goto retry;
> }
This stopped the panics (the double panics, I should say).
> if it fails you may try TD_SET_SUSPENDED(td) instead, but I think this
> is better.
This I haven't tried.
--
Daniel C. Sobral (8-DCS)
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