Date: Wed, 03 Dec 2003 15:05:38 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Igor Sysoev <is@rambler-co.ru> Cc: freebsd-current@FreeBSD.org Subject: Re: A page fault in subr_turnstile.c:propogate_priority() Message-ID: <XFMail.20031203150538.jhb@FreeBSD.org> In-Reply-To: <Pine.BSF.4.21.0312032133500.24397-100000@is>
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On 03-Dec-2003 Igor Sysoev wrote:
> On Wed, 3 Dec 2003, John Baldwin wrote:
>
>> On 03-Dec-2003 Igor Sysoev wrote:
>> > On Wed, 3 Dec 2003, John Baldwin wrote:
>> >
>> >>
>> >> On 03-Dec-2003 Igor Sysoev wrote:
>> >> > On Wed, 3 Dec 2003, John Baldwin wrote:
>> >> >
>> >> >> On 03-Dec-2003 Brian F. Feldman wrote:
>> >> >> > Igor Sysoev <is@rambler-co.ru> wrote:
>> >> >> >> I'd cvsup'ed 5.1-CURRENT from 2003.11.04.02.02.00 up to
>> >> >> >> 2003.11.28.00.00.00 with the turnstile support and it can still
>> >> >> >> causes sometimes a page fault in propogate_priority().
>> >> >> >> I have core dump and can send debug output.
>
>> Both faults are a trap 12 page fault with a faulting va of 0xe5
>> because td1 is NULL in priority propagation. Try this change to
>> get a better cashdump that can be analyzed:
>>
>> Index: subr_turnstile.c
>> ===================================================================
>> RCS file: /usr/cvs/src/sys/kern/subr_turnstile.c,v
>> retrieving revision 1.134
>> diff -u -r1.134 subr_turnstile.c
>> --- subr_turnstile.c 12 Nov 2003 23:48:42 -0000 1.134
>> +++ subr_turnstile.c 3 Dec 2003 17:48:02 -0000
>> @@ -254,6 +254,7 @@
>> }
>>
>> td1 = TAILQ_PREV(td, threadqueue, td_lockq);
>> + MPASS(td1 != NULL);
>> if (td1->td_priority <= pri) {
>> mtx_unlock_spin(&tc->tc_lock);
>> continue;
>>
>> Then print 'td' and '*ts' in gdb from the priority_propagation()
>> frame and mail the output.
>
> With a patch from http://www.FreeBSD.org/~jhb/patches/turnstile.patch
> I can not even rebuild kernel. Can I add MPASS to sources from
> 2003.11.28.00.00.00 ?
Sure. I've reproduced a panic locally with turnstile.patch. I can't
get my box to get a crash dump though. The ata crash dump code seems
to have panicd. :( Just revert turnstile.patch for now.
--
John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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