Date: Sat, 6 Jan 2007 12:01:51 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: Ceri Davies <ceri@submonkey.net> Cc: stable@FreeBSD.org Subject: Re: (audit?) Panic in 6.2-PRERELEASE Message-ID: <20070106120040.N46119@fledge.watson.org> In-Reply-To: <20070105150857.GC7088@submonkey.net> References: <20070105111954.GA51511@submonkey.net> <20070105120539.H46119@fledge.watson.org> <20070105131528.GB7088@submonkey.net> <20070105133028.F98541@fledge.watson.org> <20070105150857.GC7088@submonkey.net>
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On Fri, 5 Jan 2007, Ceri Davies wrote: > On Fri, Jan 05, 2007 at 01:34:04PM +0000, Robert Watson wrote: >> >> On Fri, 5 Jan 2007, Ceri Davies wrote: >> >>>> Much as I would love to trust the contents of ub there, I suspect they >>>> can't be trusted. Could you print the contents of *fp in kern_fstat() in >>>> both of those stacks? I'd particularly like to know the value of >>>> fp->f_type, and then depending on the type, possibly the contents of >>>> *(struct vnode *)fp->f_vnode for DTYPE_VNODE/TYPE_FIFO or *(struct socket >>>> *)fp->f_data in the case of DTYPE_SOCKET. >>> >>> Can you tell me how to get at *fp given that the stack trace shows fstat() >>> and not kern_fstat()? Sorry if I'm being dumb but I don't know how to >>> step into the kern_fstat() call from fstat(). >> >> It could be that the stack is hosed losing the frame, or maybe it's inlined >> (more likely the former I think, as kern_fstat() is a symbol used elsewhere >> in the kernel). The best bet may be to use the file descriptor number >> (uap->fd) to pull the struct file reference out of the process. Something >> on the order of (td->td_proc->p_fd->fd_ofiles[fd]) should return the right >> struct file *. > > OK, got it. They're both sockets, data in the attachments. > >> How reproduceable is this? > > So far it's happened this morning and yesterday morning. I haven't seen it > before that. I don't know the cause so I can't reproduce it at will, but > the logs don't give any indication. Chances are that it will happen again > tomorrow, but we'll see. Hmm. It looks like you printf *(td->td_proc->p_fd->fd_ofiles) without the array index. Could you repeat that, but with the array index -- i.e., td->td_proc->p_fd->fd_ofiles[uap->fd]? Also, it would probably be useful to print uap->fd. Right now you're printing stdin (index 0), but if the index is non-0, we want a different file. thanks, Robert N M Watson Computer Laboratory University of Cambridge
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