From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: Linux 2.6.26-rc4
Date: Tue, 3 Jun 2008 11:40:35 +0100
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To: Miklos Szeredi <miklos@szeredi.hu>
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On Tue, Jun 03, 2008 at 12:13:54PM +0200, Miklos Szeredi wrote:
> 
> http://www.kerneloops.org/raw.php?rawid=12419&msgid=
> 
> Looks like a negative inode in S_ISDIR(mnt->mnt_root->d_inode->i_mode),
> which would be due to NFS not properly filling in its root dentry?

Look more carefully.  It's path->dentry; aside of the fact that dentry
pointer is fetched at offset 8 from one of the arguments (fits path->dentry,
too low for mnt->mnt_root), do_add_mount() itself has just done S_ISLNK
on the very same thing, so it'd die before getting to graft_tree().

No, it's either path_lookup() somehow returning a negative dentry in
do_mount() (which shouldn't be possible, unless it's some crap around
return_reval in __link_path_walk()) or it's follow_down() giving us
a negative dentry.  Which almost certainly would've exploded prior to
that...