Date: Fri, 4 Jan 2008 12:56:42 -0500 From: John Baldwin <jhb@freebsd.org> To: Tai-hwa Liang <avatar@mmlab.cse.yzu.edu.tw> Cc: Remko Lodder <remko@freebsd.org>, freebsd-current@freebsd.org, kib@freebsd.org Subject: Re: [Fwd: Re: kern/118258 sysctl causing panics on 7.0-xxx] Message-ID: <200801041256.43153.jhb@freebsd.org> In-Reply-To: <0801041816427.55589@www.mmlab.cse.yzu.edu.tw> References: <474D81DB.7020004@FreeBSD.org> <200801031652.20807.jhb@freebsd.org> <0801041816427.55589@www.mmlab.cse.yzu.edu.tw>
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On Friday 04 January 2008 05:19:28 am Tai-hwa Liang wrote: > On Thu, 3 Jan 2008, John Baldwin wrote: > > On Thursday 29 November 2007 10:53:32 pm Tai-hwa Liang wrote: > >> On Wed, 28 Nov 2007, Remko Lodder wrote: > >>> Hello, > >>> > >>> So as per Jeff's information, can someone from the -current > >>> list either contact jeff or try to resolve the problems > >>> mentioned? :) > >> > >> This is a longstanding bug which also exists in RELENG_6. It turns out > >> that 'sysctl kern.ttys' after a terminal device is removed could trigger > >> this panic reliably. For example, do 'sysctl kern.ttys' multiple times > >> after detaching an USB serial-to-rs232 cable or a PCMCIA modem card. > >> > >> Alternatively, following script would demo the panic if you don't have > >> a physically removable terminal device: > >> > >> #!/bin/sh > >> # > >> # Warning! Running this script as root will panic your CURRENT box... > >> # > >> while true; do > >> kldload dcons > >> kldunload dcons > >> ls /dev > >> sysctl kern.ttys > >> sleep 1 > >> done > >> > >> This seems to be a race between devfs and destroy_dev(), Cc'ing kib@ > >> since he probably has more clues in this area. > > > > Try this patch. Also available at > > http://www.FreeBSD.org/~jhb/patches/ttys_sysctl.patch > > With this patch, -CURRENT no longer boots and panics as follows: Fixed, was missing an unlock at the bottom of the loop. Patch is updated at the same URL. -- John Baldwin
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