Subject: procfs locking troubles
To: None <>
From: None <>
List: current-users
Date: 02/10/2004 20:28:30
hi folks, I've seen the following on my console (I need to write it down
cause syslog didn't log it):

Simple_lock: locking against myself
lock: 0xcb625b74, currently at: /usr/src/sys/kern/kern_descrip.c:202 on cpu 0
last locked: /usr/src/sys/kern/kern_descrip.c:202
last unlocked: /usr/src/sys/kern/sys_generic.c:97

(repeated several times)

pool_cache_get(PR_WAITOK) with held simple_lock 0xcb625b74 CPU 0 /usr/src/sys/kern/kern_descrip.c:202

simple_lock: locking against myself
(same as above, repeated several times again)

$ gdb /netbsd
(gdb) x 0xcb625b74:     Cannot access memory at address 0xcb625b74

hhhmmmmm strange...

$ ident /netbsd
$NetBSD: kern_descrip.c,v 1.123 2004/01/07 09:26:29 jdolecek Exp $
$NetBSD: sys_generic.c,v 1.80 2003/10/10 15:24:28 chs Exp $
$NetBSD: procfs_vnops.c,v 1.110 2003/10/30 01:58:18 simonb Exp $

$ uname -a
NetBSD localhost 1.6ZJ NetBSD 1.6ZJ (KOERNEL.MP) #1: Tue Feb 10 16:43:18 CET 2004  skrueger@localhost:/usr/src/sys/arch/i386/compile/KOERNEL.MP i386

I've also seen:

simple_lock: locking against myself
lock: 0xcb625d04, currently at: /usr/src/sys/kern/kern_descript.c:202 on cpu 0
last locked: /usr/src/sys/kern/kern_descript.c:202
last unlocked: /usr/src/sys/miscfs/procfs/procfs_vnops.c:954

and some other msgs, but I wasn't able to catch them :-(

how to reproduce:

compile your kernel with LOCKDEBUG and DIAGNOSTIC, (and MPDEBUG in my case)
# mount -t procfs -o linux procfs /proc # don't know if linux is related, but again my case
$ tar cf - /proc > /dev/null

running this several times locked my machine up, screen freezed, no keyboard...

hope this helps,

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