Date: Wed, 07 Feb 2001 16:40:13 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: Andrea Campi <andrea@webcom.it> Cc: current@FreeBSD.org, "Crist J. Clark" <cjclark@reflexnet.net>, Jim Bloom <bloom@acm.org> Subject: Re: Kernel Panic from Yesterday's CVSup Message-ID: <XFMail.010207164013.jhb@FreeBSD.org> In-Reply-To: <20010207235459.B534@webcom.it>
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On 07-Feb-01 Andrea Campi wrote:
> On Wed, Feb 07, 2001 at 02:20:43PM -0800, John Baldwin wrote:
>>
>> On 07-Feb-01 Andrea Campi wrote:
>> > Running a kernel I got with this:
>> >
>> >>
>> >> cvs co -D"2001-01-30" src/sys
>> >>
>> >
>> > /ithread.c/1.10/Mon Dec 4 21:15:14 2000//D2001.01.29.23.00.00
>> >
>> > I get:
>> >
>> > panic: malloc(M_WAITOK) in interrupt context
>> > Debugger("panic")
>> > Stopped at Debugger+0x45: pushl %ebx
>> > db> trace
>> > Debugger(c02119a3) at Debugger+0x45
>> > panic(....)
>> > malloc(48,c0238100,0,c65feb80,0) at malloc+0x2a
>> > exit1(c65feb80,0,0,c6623f78,c01fc852) at exit1+0x1b1
>> > kthread_suspend(0,c0279a40,0,c022d1ec,a2) at kthread_suspend
>> > ithd_loop(0,c6623fa8) at ithd_loop+0x56
>> > fork_exit(c01fc7fc,0,c6623fa8) at fork_exit+0x8
>> > fork_trampoline() at fork_trampoline+0x8
>> > db> witness_list
>> > "Giant" (0xc0279a40) locked at ../../i386/isa/ithread.c:162
>>
>> Erm, ithd_loop() doesn't call kthread_suspend(). *sigh*. Something
>> else is rather messed up here I'm afraid.
>
> So I thought... also, kthread_suspend() doesn't call exit1(), does it?
>
>
> No matter what, ithd_loop() calls kthread_exit() which calls exit1()
> which happily MALLOC's with M_WAITOK...
> Something is messed up, indeed, but it seems to be a case of WISIWYG instead
> of what I mean... ;-)
>
>
> Also, I think this issue has been there longer but it might have been masked
> by me not having INVARIANTS defined at times (am I correct to read the code
> as
> not panicing #ifndef INVARIANTS?). So I am going back before this revision:
>
> revision 1.78
> date: 2001/01/21 19:25:07; author: jake; state: Exp; lines: +3 -2
> Make intr_nesting_level per-process, rather than per-cpu. Setup
> interrupt threads to run with it always >= 1, so that malloc can
> detect M_WAITOK from "interrupt" context. This is also necessary
> in order to context switch from sched_ithd() directly.
Yes, the intr_nesting_level needs to be dropped before calling kthread_exit().
I have this fixed in a different manner locally. You can try that to see if it
gets farther. However, your problems with lpr are a known problem and one that
is in the process of being fixed.
--
John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.Baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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