Date: Tue, 20 Oct 1998 18:31:48 +0930 From: Greg Lehey <grog@lemis.com> To: Stephen Suryaputra <surya@ISI.EDU>, freebsd-hackers@FreeBSD.ORG Subject: Re: Page fault while in kernel mode, bug? Message-ID: <19981020183148.G21008@freebie.lemis.com> In-Reply-To: <Pine.SUN.3.96.981020012904.2505A-100000@zephyr.isi.edu>; from Stephen Suryaputra on Tue, Oct 20, 1998 at 01:38:21AM -0700 References: <Pine.SUN.3.96.981020012904.2505A-100000@zephyr.isi.edu>
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On Tuesday, 20 October 1998 at 1:38:21 -0700, Stephen Suryaputra wrote: > Hi, > > I was running a big simulation as root. I know it is wrong but I want to > gain full access to the resources (I tried to setup the limits in > /etc/login.conf with no success... however, this part is mine to figure > out). When I ran the simulation, I found a seems like interesting bug that > you might probably interested in taking a look. Here is a snapshot of the > kernel debugger screen: > >> --- >> Fatal trap 12: page fault while in kernel mode >> fault virtual address = 0x2b2 >> fault code = supervisor read, page not present >> instruction pointer = 0x8:0xf01434ba >> stack pointer = 0x10:0xefbfff2c >> frame pointer = 0x10:0xf2830400 >> code segment = base 0x0, limit 0xfffff, type 0x1b >> = DPL 0, pres 1, def32 1, gran 1 >> processor eflags = interrupt enabled, resume, IOPL = 0 >> current process = 2 (page daemon) >> interrupt mask = >> kernel: type 12 trap, code=0 >> Stopped at _vput+0x1a: movl 0x1c(%ebx),%edx > > This error hit me several times, and for curiosity, I ran exactly the same > simulation on two machines and both get the same error, at the same > instruction pointer. The interesting part, is that the error shows that > there is a page fault in kernel mode. > > I ran it on FreeBSD-2.2.6-RELEASE and while I ran it, several messages > showed up saying that there is not enough swap space. Try adding swap and see if you can still reproduce the bug. > I will be very happy to reproduce the error, and work together with you to > find out what's wrong. Look at the section on kernel debugging in the online handbook (in case of doubt, http://www.freebsd.org/handbook/handbook293.html#634). The most important thing to get is a stack backtrace. That might even be enough to say what is causing the problem. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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