Date: Tue, 31 May 2011 15:02:37 -0700 From: mdf@FreeBSD.org To: "Kenneth D. Merry" <ken@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r222537 - in head/sys: kern sys Message-ID: <BANLkTinThaAeP9cAVpoGxpSNq2zn%2Ba-P6Q@mail.gmail.com> In-Reply-To: <20110531214618.GA57498@nargothrond.kdm.org> References: <201105311729.p4VHTwrZ033296@svn.freebsd.org> <BANLkTim1AQQj1BfqHtYfPWrvaQBp41qDNw@mail.gmail.com> <20110531214618.GA57498@nargothrond.kdm.org>
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On Tue, May 31, 2011 at 2:46 PM, Kenneth D. Merry <ken@freebsd.org> wrote: > On Tue, May 31, 2011 at 14:00:18 -0700, mdf@FreeBSD.org wrote: >> On Tue, May 31, 2011 at 10:29 AM, Kenneth D. Merry <ken@freebsd.org> wro= te: >> > Author: ken >> > Date: Tue May 31 17:29:58 2011 >> > New Revision: 222537 >> > URL: http://svn.freebsd.org/changeset/base/222537 >> > >> > Log: >> > ?Fix apparent garbage in the message buffer. >> > >> > ?While we have had a fix in place (options PRINTF_BUFR_SIZE=3D128) to = fix >> > ?scrambled console output, the message buffer and syslog were still ge= tting >> > ?log messages one character at a time. ?While all of the characters st= ill >> > ?made it into the log (courtesy of atomic operations), they were often >> > ?interleaved when there were multiple threads writing to the buffer at= the >> > ?same time. >> >> This seems to panic my box with "lock "msgbuf" 0xfffffe0127ffffe0 >> already initialized". >> >> Unfortunately, though I booted with a fresh CURRENT this morning >> successfully, both /boot/kernel and /boot/kernel.old give this panic. >> To add insult to injury, when the kernel drops into the debugger, my >> keyboard input no longer works so I can't get a stack, etc. > > Uh-oh! > >> So: >> >> 1) Is there anything else I can do to help debug this? >> 2) how can I resurrect this box without a reinstall? >> >> I will try to repro on a virtual machine so I have a snapshot to come ba= ck to. > > My guess is that this is an issue with the message buffer reinitializatio= n > path. =A0lock_init() (called by mtx_init()) has an assert to make sure th= at > the lock is initialized, and that is just a flag check. > > Since the spin lock is part of the message buffer structure, if it is hel= d > over from a previous boot, the LO_INITIALIZED flag may still be set. > > Try power cycling the machine. =A0If it is an issue with re-initializatio= n, > that should clear the memory and allow you to boot. Hmm, apparently my previous presses of the power button weren't long enough. I let it sit off for 20 seconds and it boots okay now. Thanks, matthew > My testing has been with VMs (under Xen), so the reinit path has probably > not been tested as fully as it should have been. =A0Sorry about that! > > As for the debugger, that's another issue altogether. =A0It does work for= me, > but then again if the spin lock initialization is broken for the message > buffer that may affect things. > > Try a cold boot and see if that helps. =A0If so, I think we can probably = just > bzero the mutex in msgbuf_reinit() and that will fix things. > > Ken > -- > Kenneth Merry > ken@FreeBSD.ORG >
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