Re: panic - Attempting to free lock with active block list

[Chris Wright <chrisw@osdl.org>]

* Jan-Frode Myklebust (Jan-Frode.Myklebust@bccs.uib.no) wrote:
> We have a couple of mail-servers running first 2.6.9-1.681_FC3smp
> and was later upgraded to the Fedora test kernel 2.6.10-1.727_FC3smp
> which I think is pretty plain 2.6.10 + ac2. But they both keep
> crashing with the message:
> 
>        Kernel panic - not syncing: Attempting to free lock with active block list
> 
> Any ideas how to attack this?
> 
> We're running Centos 3.3, ext3 for root-disks, ext2 on /boot,
> XFS for mail-spools, lots of nfs-mounted directories..

It seems likely it's nfs related in this case since it stresses the
fs/locks code differently than local filesystems.  I recall Steve French
reporting similar issue with cifs last month.

Message-Id: <1102097193.3540.4.camel@smfhome1.smfdom>

Are those three cases really panic-worthy?  Could we change to BUG_ON()
and try and get some useful debugging?  Trond, Willy, any ideas?

thanks,
-chris

===== fs/locks.c 1.76 vs edited =====
--- 1.76/fs/locks.c	2005-01-04 18:48:28 -08:00
+++ edited/fs/locks.c	2005-01-05 12:31:34 -08:00
@@ -159,14 +159,20 @@ static inline void locks_free_lock(struc
 		BUG();
 		return;
 	}
-	if (waitqueue_active(&fl->fl_wait))
-		panic("Attempting to free lock with active wait queue");
+	if (waitqueue_active(&fl->fl_wait)) {
+		printk("Attempting to free lock with active wait queue");
+		BUG();
+	}
 
-	if (!list_empty(&fl->fl_block))
-		panic("Attempting to free lock with active block list");
+	if (!list_empty(&fl->fl_block)) {
+		printk("Attempting to free lock with active block list");
+		BUG();
+	}
 
-	if (!list_empty(&fl->fl_link))
-		panic("Attempting to free lock on active lock list");
+	if (!list_empty(&fl->fl_link)) {
+		printk("Attempting to free lock on active lock list");
+		BUG();
+	}
 
 	if (fl->fl_ops) {
 		if (fl->fl_ops->fl_release_private)