Date: Mon, 12 Mar 2001 14:40:58 +0000 From: Ian Dowse <iedowse@maths.tcd.ie> To: j mckitrick <jcm@FreeBSD-uk.eu.org> Cc: Alfred Perlstein <bright@wintelcom.net>, freebsd-stable@freebsd.org, iedowse@maths.tcd.ie Subject: Re: suspend/restore with ppp connections Message-ID: <200103121440.aa97105@salmon.maths.tcd.ie> In-Reply-To: Your message of "Mon, 12 Mar 2001 13:58:26 GMT." <20010312135826.F86948@dogma.freebsd-uk.eu.org>
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In message <20010312135826.F86948@dogma.freebsd-uk.eu.org>, j mckitrick writes:
>
>This *is* userland ppp. I've never used pppd.
I saw a crash like this recently - I didn't get a trace/core due
to forgetting to set dumpdev and being in X, but thanks to the way
Vaios don't clear memory on a reboot, I think I got enough to track
this down:
sio1: still open, forcing close
sio1: unloaded
sio1: detached
pccard: card disabled, slot 0
resumed from suspended mode (slept 00:00:09)
pccard: card inserted, slot 0
ata0: resetting devices .. done
sio1 at port 0x2f8-0x2ff irq 11 slot 0 on pccard0
sio1: type 16550A
Fatal trap 12: page fault while in kernel mode
fault virtual address = 0x8c
fault code = supervisor read, page not present
instruction pointer = 0x8:0xc02b6c99
stack pointer = 0x10:0xc71fdd48
frame pointer = 0x10:0xc71fdd90
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 = 12580 (ppp)
interrupt mask = none
trap number = 12
panic: page fault
syncing disks... 7
done
Uptime: 2d16h40m24s
The eip value corresponds to the first dereference of com->tp in
sioioctl():
tp = com->tp;
...
term = tp->t_termios;
The problem is that the card has been reattached, so com->gone is
0. However com->tp is NULL because the driver has not seen an open()
since attachment. It would probably be possible to add a few tests
for com->tp != NULL in a few places, but sio.c has bigger problems
in this area. It seems that a struct tty will be leaked for every
insert/removal too. There is also a missing call to the line
discipline's l_close function in the forced detach case.
A workaround for the panic, I think, is to remove the card before
resuming if you accidentally suspend while ppp is running.
Ian
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