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You don't have to read all this, just jump to the end of this mail,
Section 8, for the interesting part.
[1.] One line summary of the problem:
Kernel NULL pointer in ISDN subsystem resulting in Oops and panic
[2.] Full description of the problem/report:
Kernel Oops and resulting panic in isdn_ppp_xmit.
Happened several times so far, during normal operation with heavy load
on ISDN link.
I've got a patch solving at least the NULL pointer exception, but the
real cause is commented as "should not happen", so maybe someone should
have a look. See Section 8 at the end of this report.
[3.] Keywords (i.e., modules, networking, kernel):
isdn ppp isdn_ppp_xmit NULL pointer
[4.] Kernel version (from /proc/version):
Linux version 2.4.20 (root@server.gagern.sytes.net) (gcc version 3.2.2)
#14 SMP Wed Jun 4 20:44:10 CEST 2003
[5.] Output of Oops.. message (if applicable) with symbolic information
resolved (see Documentation/oops-tracing.txt)
Unable to handle kernel NULL pointer dereference at virtual address 0000012c
*pde=00000000
Oops: 0002
CPU: 0
EIP: 0010:[<c02d4d9c>] Not tainted
EFLAGS: 00010286
eax: 00000029 esi: dfd91800 edi: 00000000 ebp: 0000000a
ds: 0018 es: 0018 ss: 0018
Stack: c03bcd40 de44ba10 ...
Code: c6 87 2c 01 00 00 01 b8 00 e0 ff ff 21 e0 8b 40 30 c1 e0 05
<0> Kernel panic: Aiee, killing interrupt handler!
In interrupt handler - not syncing
>>EIP; c02d4d9c <isdn_ppp_xmit+26c/6f0> <=====
>>esi; dfd91800 <_end+1f8ca2a8/208c5b08>
>>esp; ca7d7a6c <_end+a310514/208c5b08>
Code; c02d4d9c <isdn_ppp_xmit+26c/6f0>
00000000 <_EIP>:
Code; c02d4d9c <isdn_ppp_xmit+26c/6f0> <=====
0: c6 87 2c 01 00 00 01 movb $0x1,0x12c(%edi) <=====
Code; c02d4da3 <isdn_ppp_xmit+273/6f0>
7: b8 00 e0 ff ff mov $0xffffe000,%eax
Code; c02d4da8 <isdn_ppp_xmit+278/6f0>
c: 21 e0 and %esp,%eax
Code; c02d4daa <isdn_ppp_xmit+27a/6f0>
e: 8b 40 30 mov 0x30(%eax),%eax
Code; c02d4dad <isdn_ppp_xmit+27d/6f0>
11: c1 e0 05 shl $0x5,%eax
[6.] A small shell script or example program which triggers the
problem (if possible)
Impossible.
[7.] Environment
[7.1.] Software (add the output of the ver_linux script here)
Gentoo Linux
Linux server.gagern.sytes.net 2.4.20 #14 SMP Wed Jun 4 20:44:10 CEST
2003 i686 Pentium III (Coppermine) GenuineIntel GNU/Linux
Gnu C 3.2.2
Gnu make 3.80
util-linux 2.11y
mount 2.11y
modutils 2.4.25
e2fsprogs 1.33
reiserfsprogs 3.6.8
Linux C Library 2.3.1
Dynamic linker (ldd) 2.3.1
Procps 3.1.8
Net-tools 1.60
Kbd 1.06
Sh-utils 2.0.15
Modules Loaded snd-pcm-oss tvmixer snd-mixer-oss tuner tvaudio
msp3400 bttv i2c-algo-bit i2c-core videodev snd-emu10k1 snd-pcm
snd-timer snd-hwdep snd-util-mem snd-page-alloc snd-rawmidi
snd-seq-device snd-ac97-codec snd
[7.2.] Processor information (from /proc/cpuinfo):
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 8
model name : Pentium III (Coppermine)
stepping : 10
cpu MHz : 999.690
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 mmx fxsr sse
bogomips : 1992.29
processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 8
model name : Pentium III (Coppermine)
stepping : 10
cpu MHz : 999.690
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 mmx fxsr sse
bogomips : 1998.84
[7.3.] Module information (from /proc/modules):
snd-pcm-oss 40132 0 (autoclean)
tvmixer 3760 1 (autoclean)
snd-mixer-oss 13880 1 (autoclean) [snd-pcm-oss]
tuner 10240 1 (autoclean)
tvaudio 12924 0 (autoclean) (unused)
msp3400 16972 1 (autoclean)
bttv 70304 1 (autoclean)
i2c-algo-bit 7624 1 (autoclean) [bttv]
i2c-core 13124 0 (autoclean) [tvmixer tuner tvaudio
msp3400 bttv i2c-algo-bit]
videodev 6304 3 (autoclean) [bttv]
snd-emu10k1 73396 1
snd-pcm 62688 0 [snd-pcm-oss snd-emu10k1]
snd-timer 15592 0 [snd-pcm]
snd-hwdep 5312 0 [snd-emu10k1]
snd-util-mem 1296 0 [snd-emu10k1]
snd-page-alloc 4960 0 [snd-emu10k1 snd-pcm]
snd-rawmidi 13888 0 [snd-emu10k1]
snd-seq-device 4388 0 [snd-emu10k1 snd-rawmidi]
snd-ac97-codec 37760 0 [snd-emu10k1]
snd 31012 0 [snd-pcm-oss snd-mixer-oss snd-emu10k1
snd-pcm snd-timer snd-hwdep snd-util-mem snd-rawmidi snd-seq-device
snd-ac97-codec]
[7.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem)
0000-001f : dma1
0020-003f : pic1
0040-005f : timer
0060-006f : keyboard
0070-007f : rtc
0080-008f : dma page reg
00a0-00bf : pic2
00c0-00df : dma2
00f0-00ff : fpu
0170-0177 : ide1
01f0-01f7 : ide0
02f8-02ff : serial(auto)
0376-0376 : ide1
03c0-03df : vesafb
03f6-03f6 : ide0
03f8-03ff : serial(auto)
0cf8-0cff : PCI conf1
5000-500f : VIA Technologies, Inc. VT82C686 [Apollo Super ACPI]
9000-90ff : ATI Technologies Inc Rage XL
9400-940f : VIA Technologies, Inc. VT82C586B PIPC Bus Master IDE
9400-9407 : ide0
9408-940f : ide1
9800-981f : VIA Technologies, Inc. USB
9c00-9c1f : VIA Technologies, Inc. USB (#2)
a000-a007 : Promise Technology, Inc. 20267
a000-a007 : ide2
a400-a403 : Promise Technology, Inc. 20267
a402-a402 : ide2
a800-a807 : Promise Technology, Inc. 20267
a800-a807 : ide3
ac00-ac03 : Promise Technology, Inc. 20267
ac02-ac02 : ide3
b000-b03f : Promise Technology, Inc. 20267
b000-b007 : ide2
b008-b00f : ide3
b010-b03f : PDC20267
b400-b43f : Intel Corp. 82557/8/9 [Ethernet Pro 100]
b400-b43f : eepro100
b800-b83f : Intel Corp. 82557/8/9 [Ethernet Pro 100] (#2)
b800-b83f : eepro100
bc00-bc1f : Creative Labs SB Live! EMU10k1
bc00-bc1f : EMU10K1
c000-c007 : Creative Labs SB Live! MIDI/Game Port
c400-c41f : AVM Audiovisuelles MKTG & Computer System GmbH A1 ISDN [Fritz]
c400-c41f : avm PCI
00000000-0009fbff : System RAM
0009fc00-0009ffff : reserved
000a0000-000bffff : Video RAM area
000c0000-000c7fff : Video ROM
000c8000-000cffff : Extension ROM
000f0000-000fffff : System ROM
00100000-1ffeffff : System RAM
00100000-0036d96b : Kernel code
0036d96c-003fdda7 : Kernel data
1fff0000-1fff2fff : ACPI Non-volatile Storage
1fff3000-1fffffff : ACPI Tables
d0000000-d3ffffff : VIA Technologies, Inc. VT82C693A/694x [Apollo PRO133x]
d4000000-d4ffffff : ATI Technologies Inc Rage XL
d4000000-d43fffff : vesafb
d6000000-d60fffff : Intel Corp. 82557/8/9 [Ethernet Pro 100]
d6100000-d61fffff : Intel Corp. 82557/8/9 [Ethernet Pro 100] (#2)
d6200000-d621ffff : Promise Technology, Inc. 20267
d6220000-d6220fff : ATI Technologies Inc Rage XL
d6221000-d6221fff : Intel Corp. 82557/8/9 [Ethernet Pro 100] (#2)
d6221000-d6221fff : eepro100
d6222000-d6222fff : Intel Corp. 82557/8/9 [Ethernet Pro 100]
d6222000-d6222fff : eepro100
d6223000-d6223fff : Brooktree Corporation Bt878 Video Capture
d6223000-d6223fff : bttv
d6224000-d6224fff : Brooktree Corporation Bt878 Audio Capture
d6225000-d622501f : AVM Audiovisuelles MKTG & Computer System GmbH A1
ISDN [Fritz]
fec00000-fec00fff : reserved
fee00000-fee00fff : reserved
ffff0000-ffffffff : reserved
[7.5.] PCI information ('lspci -vvv' as root)
PCI devices found:
Bus 0, device 0, function 0:
Host bridge: VIA Technologies, Inc. VT82C693A/694x [Apollo PRO133x]
(rev 196
).
Prefetchable 32 bit memory at 0xd0000000 [0xd3ffffff].
Bus 0, device 1, function 0:
PCI bridge: VIA Technologies, Inc. VT82C598/694x [Apollo
MVP3/Pro133x AGP] (
rev 0).
Master Capable. No bursts. Min Gnt=4.
Bus 0, device 6, function 0:
VGA compatible controller: ATI Technologies Inc Rage XL (rev 39).
IRQ 19.
Master Capable. Latency=32. Min Gnt=8.
Non-prefetchable 32 bit memory at 0xd4000000 [0xd4ffffff].
I/O at 0x9000 [0x90ff].
Non-prefetchable 32 bit memory at 0xd6220000 [0xd6220fff].
Bus 0, device 7, function 0:
ISA bridge: VIA Technologies, Inc. VT82C686 [Apollo Super South]
(rev 64).
Bus 0, device 7, function 1:
IDE interface: VIA Technologies, Inc. VT82C586B PIPC Bus Master IDE
(rev 6).
Master Capable. Latency=32.
I/O at 0x9400 [0x940f].
Bus 0, device 7, function 2:
USB Controller: VIA Technologies, Inc. USB (rev 22).
IRQ 19.
Master Capable. Latency=32.
I/O at 0x9800 [0x981f].
Bus 0, device 7, function 3:
USB Controller: VIA Technologies, Inc. USB (#2) (rev 22).
IRQ 19.
Master Capable. Latency=32.
I/O at 0x9c00 [0x9c1f].
Bus 0, device 7, function 4:
Non-VGA unclassified device: VIA Technologies, Inc. VT82C686 [Apollo
Super A
CPI] (rev 64).
IRQ 9.
Bus 0, device 12, function 0:
RAID bus controller: Promise Technology, Inc. 20267 (rev 2).
IRQ 16.
Master Capable. Latency=32.
I/O at 0xa000 [0xa007].
I/O at 0xa400 [0xa403].
I/O at 0xa800 [0xa807].
I/O at 0xac00 [0xac03].
I/O at 0xb000 [0xb03f].
Non-prefetchable 32 bit memory at 0xd6200000 [0xd621ffff].
Bus 0, device 13, function 0:
Ethernet controller: Intel Corp. 82557/8/9 [Ethernet Pro 100] (rev 8).
IRQ 17.
Master Capable. Latency=32. Min Gnt=8.Max Lat=56.
Non-prefetchable 32 bit memory at 0xd6222000 [0xd6222fff].
I/O at 0xb400 [0xb43f].
Non-prefetchable 32 bit memory at 0xd6000000 [0xd60fffff].
Bus 0, device 14, function 0:
Ethernet controller: Intel Corp. 82557/8/9 [Ethernet Pro 100] (#2)
(rev 8).
IRQ 18.
Master Capable. Latency=32. Min Gnt=8.Max Lat=56.
Non-prefetchable 32 bit memory at 0xd6221000 [0xd6221fff].
I/O at 0xb800 [0xb83f].
Non-prefetchable 32 bit memory at 0xd6100000 [0xd61fffff].
Bus 0, device 15, function 0:
Multimedia audio controller: Creative Labs SB Live! EMU10k1 (rev 7).
IRQ 17.
Master Capable. Latency=32. Min Gnt=2.Max Lat=20.
I/O at 0xbc00 [0xbc1f].
Bus 0, device 15, function 1:
Input device controller: Creative Labs SB Live! MIDI/Game Port (rev 7).
Master Capable. Latency=32.
I/O at 0xc000 [0xc007].
Bus 0, device 16, function 0:
Multimedia video controller: Brooktree Corporation Bt878 Video
Capture (rev
17).
IRQ 18.
Master Capable. Latency=32. Min Gnt=16.Max Lat=40.
Prefetchable 32 bit memory at 0xd6223000 [0xd6223fff].
Bus 0, device 16, function 1:
Multimedia controller: Brooktree Corporation Bt878 Audio Capture
(rev 17).
IRQ 18.
Master Capable. Latency=32. Min Gnt=4.Max Lat=255.
Prefetchable 32 bit memory at 0xd6224000 [0xd6224fff].
Bus 0, device 17, function 0:
Network controller: AVM Audiovisuelles MKTG & Computer System GmbH
A1 ISDN [
Fritz] (rev 2).
IRQ 19.
Non-prefetchable 32 bit memory at 0xd6225000 [0xd622501f].
I/O at 0xc400 [0xc41f].
[7.6.] SCSI information (from /proc/scsi/scsi)
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: PLEXTOR Model: CD-R PX-W2410A Rev: 1.01
Type: CD-ROM ANSI SCSI revision: 02
[7.7.] Other information that might be relevant to the problem
(please look in /proc and include all information that you
think to be relevant):
grep -iE isdn\|fritz\|hisax .config
# ISDN subsystem
CONFIG_ISDN=y
CONFIG_ISDN_BOOL=y
CONFIG_ISDN_PPP=y
CONFIG_ISDN_PPP_VJ=y
CONFIG_ISDN_MPP=y
CONFIG_ISDN_PPP_BSDCOMP=y
CONFIG_ISDN_AUDIO=y
CONFIG_ISDN_TTY_FAX=y
# ISDN feature submodules
CONFIG_ISDN_DRV_LOOP=m
CONFIG_ISDN_DIVERSION=m
# Passive ISDN cards
CONFIG_ISDN_DRV_HISAX=y
CONFIG_ISDN_HISAX=y
CONFIG_HISAX_EURO=y
# CONFIG_HISAX_NO_SENDCOMPLETE is not set
# CONFIG_HISAX_NO_LLC is not set
# CONFIG_HISAX_NO_KEYPAD is not set
# CONFIG_HISAX_1TR6 is not set
# CONFIG_HISAX_NI1 is not set
CONFIG_HISAX_MAX_CARDS=2
# CONFIG_HISAX_TELESPCI is not set
# CONFIG_HISAX_S0BOX is not set
CONFIG_HISAX_FRITZPCI=y
# CONFIG_HISAX_AVM_A1_PCMCIA is not set
# CONFIG_HISAX_ELSA is not set
# CONFIG_HISAX_DIEHLDIVA is not set
# CONFIG_HISAX_SEDLBAUER is not set
# CONFIG_HISAX_NETJET is not set
# CONFIG_HISAX_NETJET_U is not set
# CONFIG_HISAX_NICCY is not set
# CONFIG_HISAX_BKM_A4T is not set
# CONFIG_HISAX_SCT_QUADRO is not set
# CONFIG_HISAX_GAZEL is not set
# CONFIG_HISAX_HFC_PCI is not set
# CONFIG_HISAX_W6692 is not set
# CONFIG_HISAX_HFC_SX is not set
# CONFIG_HISAX_ENTERNOW_PCI is not set
CONFIG_HISAX_DEBUG=y
# CONFIG_HISAX_SEDLBAUER_CS is not set
# CONFIG_HISAX_ELSA_CS is not set
# CONFIG_HISAX_AVM_A1_CS is not set
# CONFIG_HISAX_ST5481 is not set
CONFIG_HISAX_FRITZ_PCIPNP=m
# Active ISDN cards
# CONFIG_ISDN_DRV_ICN is not set
# CONFIG_ISDN_DRV_PCBIT is not set
# CONFIG_ISDN_DRV_SC is not set
# CONFIG_ISDN_DRV_ACT2000 is not set
# CONFIG_ISDN_DRV_EICON is not set
# CONFIG_ISDN_DRV_TPAM is not set
# CONFIG_ISDN_CAPI is not set
[8.] Other notes, patches, fixes, workarounds:
Now this is the interesting part!
[8.1.] Patch to avoid NULL pointer exception
The label "unlock" would result in "spin_unlock_bh(&lp->xmit_lock)",
which is a bad idea if lp is NULL.
--- linux/drivers/isdn/isdn_ppp.c 2003-05-06 16:51:15.000000000 +0200
+++ linux/drivers/isdn/isdn_ppp.c 2003-06-24 10:42:53.000000000 +0200
@@ -1176,7 +1176,7 @@
if (!lp) {
printk(KERN_WARNING "%s: all channels busy - requeuing!\n",
netdev->name);
retval = 1;
- goto unlock;
+ goto out;
}
/* we have our lp locked from now on */
[8.2.] Corresponding part in isdn_net.h, lines 70-96
I believe the NULL pointer came from the line marked "should never
happen". Otherwise we'd have a NULL pointer exception right here, in the
spin_lock_bh.
As you can see, there should be no locks left over, so at least jumping
to out instead of unlock in the above patch should be correct in any case.
/*
* For the given net device, this will get a non-busy channel out of the
* corresponding bundle. The returned channel is locked.
*/
static __inline__ isdn_net_local * isdn_net_get_locked_lp
(isdn_net_dev *nd)
{
unsigned long flags;
isdn_net_local *lp;
spin_lock_irqsave(&nd->queue_lock, flags);
lp = nd->queue; /* get lp on top of queue */
spin_lock_bh(&nd->queue->xmit_lock);
while (isdn_net_lp_busy(nd->queue)) {
spin_unlock_bh(&nd->queue->xmit_lock);
nd->queue = nd->queue->next;
if (nd->queue == lp) { /* not found -- should never happen */
lp = NULL;
goto errout;
}
spin_lock_bh(&nd->queue->xmit_lock);
}
lp = nd->queue;
nd->queue = nd->queue->next;
errout:
spin_unlock_irqrestore(&nd->queue_lock, flags);
return lp;
}
--------------030402020103050909010103
Content-Type: text/plain;
name="isdn_ppp_xmit.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
filename="isdn_ppp_xmit.patch"
--- linux/drivers/isdn/isdn_ppp.c 2003-05-06 16:51:15.000000000 +0200
+++ linux/drivers/isdn/isdn_ppp.c 2003-06-24 10:42:53.000000000 +0200
@@ -1176,7 +1176,7 @@
if (!lp) {
printk(KERN_WARNING "%s: all channels busy - requeuing!\n", netdev->name);
retval = 1;
- goto unlock;
+ goto out;
}
/* we have our lp locked from now on */
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