Date: Mon, 22 Feb 99 15:41:50 -0800 From: Rahul Dhesi <dhesi@rahul.net> To: stable@freebsd.org Subject: Re: 3.1-RELEASE crash dump with -g kernel, 'page fault in kernel mode' Message-ID: <199902222341.AA15858@waltz.rahul.net> In-Reply-To: Message from Rahul Dhesi <dhesi@rahul.net> of Fri, 19 Feb 99 19:33:01 -0800
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I have been looking through the open PRs, and found this one that's
interesting:
kern/2717
Fatal trap 12: page fault while in kernel mode
It contains this annotation made on Date: Wed, 12 Feb 1997 17:40:11 +1100:
The standard (syscons) console driver and perhaps the pcvt console
driver have some races when kernel printfs from interrupt handlers
are mixed with normal console output.
Workarounds: don't put (m)any printfs in interrupt handlers, or don't
use /dev/ttyv0 for normal applications (it's still used for console
output by syslogd etc so this only reduces the problem), or use a
serial console.
I wonder if this is still a problem in current versions of FreeBSD? If
so, this might explain a number of different reports of 'page fault
while in kernel mode' that I have seen, including mine (below). Would
somebody who is familar with the internals of the syscons console driver
please comment?
What's interesting is that I have a machine (no keyboard) running
3.0-RELEASE doing News processing that never panics like this. It
has a /boot.config file that contains '-h', which is supposed to force
use of the serial port as console.
But a number of machine running any of 3.0-RELEASE, 3.1-RELEASE, and
various 3.0 snapshots, all with keyboard and display connected, and not
having a /boot.config file, have panic'd with 'page fault while in
kernel mode'. *IF* the use of the display is the problem, then I will
be very happy, because it's easily fixable by switching to the serial
console. I am going to try this.
If anybody else has encountered these panics, please comment.
Rahul
> Date: Fri, 19 Feb 99 19:33:01 PST
> From: Rahul Dhesi <dhesi@rahul.net>
> To: stable@freebsd.org
> Message-Id: <199902200333.AA27605@waltz.rahul.net>
> Subject: 3.1-RELEASE crash dump with -g kernel, 'page fault in kernel
*** mode'
> I am now running 3.1-RELEASE with a kernel that was compiled with -g,
> and I have a crash dump available. If anybody is interested in getting
> more details, I will be happy to provide them to you -- please contact
> me. Below is a little of what I have. This particular problem (page
> fault in kernel mode) has been occurring with various STABLE snapshots.
>
> Rahul
>
>
> Fatal trap 12: page fault while in kernel mode
> fault virtual address = 0x48
> fault code = supervisor write, page not present
>
> ...
>
> (kgdb) where
> #0 0xf015d86b in boot ()
> #1 0xf015daf0 in at_shutdown ()
> #2 0xf024c305 in trap_fatal ()
> #3 0xf024bfe3 in trap_pfault ()
> #4 0xf024bc5a in trap ()
> #5 0xf02117c8 in acquire_lock ()
> #6 0xf021440e in softdep_disk_io_initiation ()
> #7 0xf018caba in spec_strategy ()
> #8 0xf018c24d in spec_vnoperate ()
> #9 0xf021fe75 in ufs_vnoperatespec ()
> #10 0xf021f87b in ufs_strategy ()
> #11 0xf021fe45 in ufs_vnoperate ()
> #12 0xf017a023 in bwrite ()
> #13 0xf017e55a in vop_stdbwrite ()
> #14 0xf017e3a5 in vop_defaultop ()
> #15 0xf021fe45 in ufs_vnoperate ()
> #16 0xf017a9b7 in vfs_bio_awrite ()
> #17 0xf021966b in ffs_fsync ()
> #18 0xf0217b7b in ffs_sync ()
> #19 0xf0182e6f in sync ()
> #20 0xf015d6b1 in boot ()
> #21 0xf015daf0 in at_shutdown ()
> #22 0xf024c305 in trap_fatal ()
> ---Type <return> to continue, or q <return> to quit---
> #23 0xf024bfe3 in trap_pfault ()
> #24 0xf024bc5a in trap ()
> #25 0xf01eb2ad in tulip_rx_intr ()
> #26 0xf01eb9f3 in tulip_intr_handler ()
> #27 0xf01ebb51 in tulip_intr_normal ()
>
> == END ==
>
>
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