Re: panic: getnewvnode: free vnode isn't

On Sat, Dec 13, 2003 at 05:00:47PM +0000, Ian Dowse wrote:
> In message <20031210234538.GA746_at_buffy.brucec.backnet>, Bruce Cran writes:
> >#10 0xc04bb923 in panic (fmt=0xc05f16d7 "getnewvnode: free vnode isn't")
> >    at /usr/src/sys/kern/kern_shutdown.c:534
> >#11 0xc0500fb5 in getnewvnode (tag=0xc05f432f "ufs", mp=0xc43f2000, vops=0x0, 
> >    vpp=0x0) at /usr/src/sys/kern/vfs_subr.c:1004
> 
> Could people seeing this panic try the following patch? I haven't
> thought through this in much detail, but it seems that vnodes should
> be removed from the free list before being cleaned. The addition
> of the VI_DOINGINACT test about a year ago probably made this panic
> more likely, but I don't know why it has suddenly cropped up recently.
> 
> Jeff, does this look reasonable to you? It seems that while most
> callers of vclean() ensure that the vnode is not on the free list,
> some direct users of vgone/vgonel do not (e.g. vflush, vrecycle).
> This could result in a vnode being on the free list while it is
> being recycled. BTW, I think we may no longer need to increment the
> reference count in vclean(), and the comment about VOP_INACTIVE
> before the VOP_LOCK() call is no longer accurate.
> 
> I guess it's possible that this could also affect the sysinstall
> crash, but that is probably unlikely.
> 

The patch hasn't stopped the panics, but I've tracked down a series of
actions which can trigger it fairly reliably.   Firstly, the new code is run
after mounting the root filesystem (once), on shutdown lots of times,
once when I plug the USB Speedtouch 330 modem (ugen0) in (only if 'ppp
-ddial' is already running), and twice
when modem_run from the speedtouch port is run.   I ran a stress test of my 
system, compiling world, uncompressing archives, cvsupping etc
while the modem was plugged in.  I unplugged the modem,
plugged it back in, got the 'ugenread: no pipe' messages, ran modem_run
again and ppp picked up the connection again.   I then ran 'du -h /usr/src' 
and after a second the system paniced. 

--
Bruce Cran