[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]
Re: kern/47817: procfs related panic
The following reply was made to PR kern/47817; it has been noted by GNATS.
From: David Holland <dholland-bugs%netbsd.org@localhost>
Subject: Re: kern/47817: procfs related panic
Date: Mon, 7 Oct 2013 03:07:09 +0000
On Wed, May 15, 2013 at 08:10:01AM +0000, firstname.lastname@example.org wrote:
> panic: kernel diagnostic assertion "vp->v_usecount != 0" failed: file
"/usr/src/sys/kern/vfs_vnode.c", line 924
This panic means that a vnode with no references has been vref'd,
which you aren't supposed to do (it requires vget instead). I think
either this is a manifestation of one of the vnode lifecycle
conditions that hannken@ fixed recently (the one where vget could in
some circumstances return a blank vnode) ... or it indicates a
vnode refcounting problem in mounts or cwd/chroot logic. The latter is
possible of course but doesn't seem too likely.
Since the call chain goes through procfs_readlink and procfs_dir, the
vnode it's tripping on must be the target process's current dir, root
dir, or executable image... or a mount point getcwd crosses while
getcwd'ing one of these. It can't be a procfs vnode, as procfs refuses
to do that. (See PR 40549.)
I suspect it's the blank vnode issue and that this problem will be no
longer reproducible -- was it ever reproducible?
Another option is that it's somehow a manifestation of the same
problem as 40549, but I don't immediately see how.
David A. Holland
Main Index |
Thread Index |