cat s3c2440-uart.1/clock_source causes oops in s3c24xx_serial_show_clksrc

[lindi]

Steps to reproduce:
1) cat /sys/devices/platform/s3c2440-uart.1/clock_source as normal user

Expected results:
1) the system does not oops

Actual results:
1)

[ 5130.450000] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[ 5130.450000] pgd = c7b7c000
[ 5130.450000] [00000000] *pgd=36da9031, *pte=00000000, *ppte=00000000
[ 5130.450000] Internal error: Oops: 17 [#1]
[ 5130.450000] Modules linked in: ipv6 fuse btusb bluetooth ohci_hcd tun snd_soc_neo1973_gta02_wm8753 snd_soc_s3c24xx_i2s snd_soc_s3c24xx g_ether snd_soc_wm8753 snd_soc_core snd_pcm_oss snd_mixer_oss ar6000 snd_pcm snd_timer snd_page_alloc s3cmci snd s3c2410_wdt
[ 5130.450000] CPU: 0    Tainted: G        W   (2.6.29-GTA02_lindi2-andy-tracking-mokodev #4)
[ 5130.450000] PC is at s3c24xx_serial_show_clksrc+0x1c/0x30
[ 5130.450000] LR is at dev_attr_show+0x2c/0x4c
[ 5130.450000] pc : [<c0189098>]    lr : [<c0189f14>]    psr: a0000013
[ 5130.450000] sp : c6c8bec8  ip : c6c8bed8  fp : c6c8bed4
[ 5130.450000] r10: 0001b000  r9 : c6c8a000  r8 : c7b6ac38
[ 5130.450000] r7 : c037f320  r6 : c78bb5e4  r5 : c7b6ac20  r4 : c037f174
[ 5130.450000] r3 : 00000000  r2 : c7988000  r1 : 00001000  r0 : c7988000
[ 5130.450000] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[ 5130.450000] Control: c000717f  Table: 37b7c000  DAC: 00000015
[ 5130.450000] Process cat (pid: 8356, stack limit = 0xc6c8a268)
[ 5130.450000] Stack: (0xc6c8bec8 to 0xc6c8c000)
[ 5130.450000] bec0:                   c6c8beec c6c8bed8 c0189f14 c018908c c036c0f4 c7b6ac20 
[ 5130.450000] bee0: c6c8bf14 c6c8bef0 c00e1a28 c0189ef8 00000000 c6c1e640 c7b6ac20 c6c8bf78 
[ 5130.450000] bf00: 00008000 c7b6ac38 c6c8bf4c c6c8bf18 c00e1ad4 c00e19b8 c6c8bf4c c6c8bf28 
[ 5130.450000] bf20: c0034b40 c008d4e0 c6c1e640 0001b000 c6c8bf78 00008000 c002df48 00000000 
[ 5130.450000] bf40: c6c8bf74 c6c8bf50 c00a10b4 c00e1a8c 00000001 00000000 00000000 00000000 
[ 5130.450000] bf60: c6c1e640 00000003 c6c8bfa4 c6c8bf78 c00a13d0 c00a100c 00000000 00000000 
[ 5130.450000] bf80: c0034ee8 00000000 00000000 00008000 0001b000 00000003 00000000 c6c8bfa8 
[ 5130.450000] bfa0: c002dda0 c00a1394 00008000 0001b000 00000003 0001b000 00008000 0001b000 
[ 5130.450000] bfc0: 00008000 0001b000 00000003 00000003 0001b000 00000000 40025000 00000000 
[ 5130.450000] bfe0: 7fffe000 beaef1c0 0000dea0 400eea7c 60000010 00000003 00000000 00000000 
[ 5130.450000] Backtrace: 
[ 5130.450000] [<c018907c>] (s3c24xx_serial_show_clksrc+0x0/0x30) from [<c0189f14>] (dev_attr_show+0x2c/0x4c)
[ 5130.450000] [<c0189ee8>] (dev_attr_show+0x0/0x4c) from [<c00e1a28>] (fill_read_buffer+0x80/0xd4)
[ 5130.450000]  r5:c7b6ac20 r4:c036c0f4
[ 5130.450000] [<c00e19a8>] (fill_read_buffer+0x0/0xd4) from [<c00e1ad4>] (sysfs_read_file+0x58/0x114)
[ 5130.450000]  r8:c7b6ac38 r7:00008000 r6:c6c8bf78 r5:c7b6ac20 r4:c6c1e640
[ 5130.450000] [<c00e1a7c>] (sysfs_read_file+0x0/0x114) from [<c00a10b4>] (vfs_read+0xb8/0x148)
[ 5130.450000] [<c00a0ffc>] (vfs_read+0x0/0x148) from [<c00a13d0>] (sys_read+0x4c/0x7c)
[ 5130.450000]  r7:00000003 r6:c6c1e640 r5:00000000 r4:00000000
[ 5130.450000] [<c00a1384>] (sys_read+0x0/0x7c) from [<c002dda0>] (ret_fast_syscall+0x0/0x2c)
[ 5130.450000]  r6:00000003 r5:0001b000 r4:00008000
[ 5130.450000] Code: e590309c e3a01a01 e513300c e1a00002 (e5933000) 
[ 5130.450000] ---[ end trace ef85096ca71097fb ]---

More info:
1) this is with andy-tracking 2.6.29 a3587e4ed77974ad

[lindi]

This occurs also on 2.6.34

​http://www.spinics.net/lists/linux-serial/msg02683.html

might be related

[gena2x]

Here, i can reproduce it, but it seem fails only before port were opened for the first time.

neo:~# uname -a 
Linux neo 2.6.34b5-v28 #11 Sun Oct 31 17:54:41 MSK 2010 armv4tl GNU/Linux

(kernel from radek's .29 tree + jitterless ts patch v4)

fresh booted kernel:

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
neo:~# cat /sys/devices/platform/s3c2440-uart.1/clock_source 
Segmentation fault
neo:~# cat /sys/devices/platform/s3c2440-uart.1/clock_source 
Segmentation fault
neo:~# cat /dev/ttySAC1 
$GPRMC,,V,,,,,,,,,,N*53

$GPVTG,,,,,,,,,N*30

$GPGGA,,,,,,0,00,99.99,,,,,,*48

$GPGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*30

$GPGSV,1,1,00*79

$GPGLL,,,,,,V,N*64

$GPZDA,,,,,00,00*48

^C
neo:~# cat /sys/devices/platform/s3c2440-uart.1/clock_source 
* pclk

ops:

[   53.710000] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[   53.710000] pgd = c483c000
[   53.710000] [00000000] *pgd=34834031, *pte=00000000, *ppte=00000000
[   53.710000] Internal error: Oops: 17 [#2]
[   53.710000] last sysfs file: /sys/devices/platform/s3c2440-uart.1/clock_source
[   53.710000] Modules linked in: rfcomm l2cap ipv6 ppp_generic slhc g_ether joydev s3c2410_udc
[   53.710000] CPU: 0    Tainted: G      D     (2.6.34b5-v28 #11)
[   53.710000] PC is at s3c24xx_serial_show_clksrc+0x20/0x34
[   53.710000] LR is at s3c24xx_serial_show_clksrc+0x14/0x34
[   53.710000] pc : [<c02407dc>]    lr : [<c02407d0>]    psr: a0000013
[   53.710000] sp : c482dec0  ip : c482dec0  fp : c482ded4
[   53.710000] r10: c482df78  r9 : c482c000  r8 : 00001000
[   53.710000] r7 : c048dc28  r6 : c03b9a74  r5 : c7d344dc  r4 : c4825000
[   53.710000] r3 : 00000000  r2 : c4825000  r1 : 00001000  r0 : c4825000
[   53.710000] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[   53.710000] Control: c000717f  Table: 3483c000  DAC: 00000015
[   53.710000] Process cat (pid: 1611, stack limit = 0xc482c270)
[   53.710000] Stack: (0xc482dec0 to 0xc482e000)
[   53.710000] dec0: c04a1cb4 c7d344dc c482deec c482ded8 c024119c c02407cc c7d46860 c7d344dc
[   53.710000] dee0: c482df14 c482def0 c00e3420 c0241180 c7d46860 c7d46878 c6ed44a0 00015000
[   53.710000] df00: 00001000 c482c000 c482df44 c482df18 c00e3514 c00e33d0 bebfec50 00000000
[   53.710000] df20: c6ed44a0 00001000 00015000 c482df78 c0029044 40025000 c482df74 c482df48
[   53.710000] df40: c0099c18 c00e349c 00000000 00008124 00000001 c6ed44a0 00000000 00000000
[   53.710000] df60: 00000003 c0029044 c482dfa4 c482df78 c0099da4 c0099b70 00000000 00000000
[   53.710000] df80: 00001000 00000000 00000000 00001000 00015000 00015000 00000000 c482dfa8
[   53.710000] dfa0: c0028ec0 c0099d68 00001000 00015000 00000003 00015000 00001000 00015000
[   53.710000] dfc0: 00001000 00015000 00015000 00000003 7fffe000 00000000 40025000 00000000
[   53.710000] dfe0: 00000003 bebfebb8 0000ad20 400d9d5c 60000010 00000003 00000000 00000000
[   53.710000] Backtrace: 
[   53.710000] [<c02407bc>] (s3c24xx_serial_show_clksrc+0x0/0x34) from [<c024119c>] (dev_attr_show+0x2c/0x4c)
[   53.710000]  r5:c7d344dc r4:c04a1cb4
[   53.710000] [<c0241170>] (dev_attr_show+0x0/0x4c) from [<c00e3420>] (fill_read_buffer+0x60/0xcc)
[   53.710000]  r5:c7d344dc r4:c7d46860
[   53.710000] [<c00e33c0>] (fill_read_buffer+0x0/0xcc) from [<c00e3514>] (sysfs_read_file+0x88/0x94)
[   53.710000]  r9:c482c000 r8:00001000 r7:00015000 r6:c6ed44a0 r5:c7d46878
[   53.710000] r4:c7d46860
[   53.710000] [<c00e348c>] (sysfs_read_file+0x0/0x94) from [<c0099c18>] (vfs_read+0xb8/0x16c)
[   53.710000] [<c0099b60>] (vfs_read+0x0/0x16c) from [<c0099da4>] (sys_read+0x4c/0x84)
[   53.710000]  r8:c0029044 r7:00000003 r6:00000000 r5:00000000 r4:c6ed44a0
[   53.710000] [<c0099d58>] (sys_read+0x0/0x84) from [<c0028ec0>] (ret_fast_syscall+0x0/0x2c)
[   53.710000]  r6:00015000 r5:00015000 r4:00001000
[   53.710000] Code: eb000e3f e510300c e3a01a01 e1a00004 (e5933000) 
[   53.710000] ---[ end trace 6eee0da881bf3030 ]---