Date: Sun, 15 Mar 1998 22:29:54 -0000 (GMT) From: Duncan Barclay <dmlb@ragnet.demon.co.uk> To: Peter Jeremy <Peter.Jeremy@alcatel.com.au> Cc: freebsd-hackers@FreeBSD.ORG Subject: RE: IDE+LPIP causing random lockups Message-ID: <XFMail.980315222954.dmlb@computer.my.domain> In-Reply-To: <199803152137.IAA04231@gsms01.alcatel.com.au>
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On 15-Mar-98 Peter Jeremy wrote: > I have been having occasional lockups on my main system for some time > now (it occurs with all 2.2.x releases, I can't recall if 2.1.x was > affected). I am wondering if anyone else has seen something similar. > > Configuration: > main machine: VLB-based 486DX2-50 with 2 IDE disks (32-bit, multiblock 16) > on 1 (VLB) controller, running 2.2.5-R. > 2nd machine: Toshiba T1850 (386SX25 with 1 IDE disk) running 2.2.1-R > > The machines are joined by a laplink cable and use LPIP. > > The symptoms are that my main machine (only) locks up and needs a > reset to recover. The laptop has never been affected. The problem > only occurs when there is LPIP activity between the machines and seems > to also correlate with disk activity on the main machine, and using > ssh to transfer data. Running XFree86 also seems to make it worse > (but this might just be the increased disk activity associated with > running X11 in less than infinite RAM). Note that between talking to > IDE disks and communicating with a slow host via LPIP, the machine > spends a lot of time inside interrupts - often over 30% according to > top. Only to add that I have seen this happen in a similar set up. However I feel it is also to do with having a "fast" and "slow" machine. The "fast" machine dies more frequently than the "slow" machine; and it depends on which machine sets the sockets up. E.g. an rcp from "fast" to "slow" dies; but and rcp on the same file from "slow" to "fast" works! The machines are a Contura 4/25 with 8MB ram and a VESA/ISA/PCI 5x86 with 20MB both running 2.2-stable from mid summer. I posted something on this a few months ago to c.u.b.f.m. Have a look on Deja News (I managed to configure my news reader not to save posting, sorry). > > Having (finally) gotten around to loading a kernel with DDB, I find > that the lockup appears to be caused by sbcompress() attempting to > add an mbuf to itself - sbappend() is called to append an mbuf to > sockbuf that already includes that mbuf in the mbuf list. When this > is passed to sbcompress(), it winds up in an infinite loop. > > My suspicion is that something is continuing to use an mbuf after it > frees it, probably associated with some sort of interrupt window. > I've added some checks in the mbuf code to try and pick this up, but > haven't found the problem yet. I did notice that the splXXX() > routines don't atomically update cpl, but the associated comments (in > i386/include/spl.h) say this is OK. > > I have (less frequently) seen kernel page faults with addresses like > 0xf400xxxx, 0x79xxxxxx. I haven't looked into these yet. I'm hoping > they are caused by the mbuf's being used for two things at once. > > Does anyone have any ideas? You've got a lot further than I did in tracking it down! > Peter > -- > Peter Jeremy (VK2PJ) peter.jeremy@alcatel.com.au > Alcatel Australia Limited > 41 Mandible St Phone: +61 2 9690 5019 > ALEXANDRIA NSW 2015 Fax: +61 2 9690 5247 > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message --- ________________________________________________________________________ Duncan Barclay | God smiles upon the little children, dmlb@ragnet.demon.co.uk | the alcoholics, and the permanently stoned. ________________________________________________________________________ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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