linux-kernel - Re: kernel 3.8.4 : kernel BUG at fs/locks.c:2093! part #2

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 26 Mar 2013 17:37:47 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	"J. Bruce Fields" <bfields@...ldses.org>
Cc:	Toralf F??rster <toralf.foerster@....de>,
	Linux NFS mailing list <linux-nfs@...r.kernel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: kernel 3.8.4 : kernel BUG at fs/locks.c:2093!   part #2

On Tue, Mar 26, 2013 at 10:46:40AM -0400, J. Bruce Fields wrote:
> > fs/locks.c:2093 says that we did the final fput of a file that still had
> > posix locks held on it.
> > 
> > I can't see how that would happen, but admittedly the nfsd4 code here is
> > much too complicated for its own good.
> > 
> > If it were possible it would be useful to know what lead up to this.  A
> > network trace (tcpdump -s0 -wtmp.pcap, then send me tmp.pcap) would be
> > useful for that, but I fear it's probably too huge by the time you hit
> > the bug.
> > 
> > (The following warning ("rcu_sched self-detected stall") looks like the
> > result of BUGing while holding file_lock_lock.  That BUG should probably
> > be downgraded to a WARN_ON_ONCE.)
> 
> Can you run with test patches?
> 
> This just makes nfsd's fput calls synchronous so that we see in the
> backtrace who called them.
> 
> (But assuming it does turn out to be one of these callers, we may then
> need some more printk's in the nfsd code...).

Might also be a good idea to dump the offending struct file_lock, while
we are at it...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/