[Resent, with a bigger recipients list] Hi, The asus laptop driver conditionnaly registers leds in asus_led_register() depending on their availability, but unconditionnaly registers them all at exit time or when the module fails to load. Unregistering not registered leds result in the following Oops. So we should check before unregistering. DEV: Unregistering device. ID = 'asus-laptop' PM: Removing info for No Bus:asus-laptop kobject_uevent_env fill_kobj_path: path = '/class/backlight/asus-laptop' kobject asus-laptop: cleaning up DEV: Unregistering device. ID = '<NULL>' BUG: unable to handle kernel NULL pointer dereference at virtual address 00000064 printing eip: c026a9a3 *pde = 00000000 Oops: 0000 [#1] PREEMPT Modules linked in: radeon drm cpufreq_ondemand acpi_cpufreq freq_table lm90 hwmon ipv6 binfmt_misc dm_mirror dm_mod snd_intel8x0 snd_intel8x0m snd_ac97_codec snd_seq_dummy ac97_bus snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss hci_usb snd_mixer_oss bluetooth snd_pcm ohci1394 snd_timer ieee1394 sr_mod snd cdrom ipw2200 ieee80211 firewire_ohci asus_laptop rtc_cmos firewire_core button video i2c_i801 rtc_core serio_raw soundcore irda crc_ccitt crc_itu_t output ac ieee80211_crypt battery i2c_core led_class sdhci mmc_core snd_page_alloc iTCO_wdt sg rtc_lib skge ehci_hcd ohci_hcd uhci_hcd CPU: 0 EIP: 0060:[<c026a9a3>] Not tainted VLI EFLAGS: 00210296 (2.6.23-rc3-patched #2) EIP is at device_del+0xb/0x23a eax: 00000000 ebx: 00000000 ecx: 00000033 edx: f7d0c7c0 esi: f88ab580 edi: 00000880 ebp: f594ef1c esp: f594ef0c ds: 007b es: 007b fs: 0000 gs: 0033 ss: 0068 Process rmmod (pid: 2552, ti=f594e000 task=f628e5b0 task.ti=f594e000) Stack: c011fb2e 00000000 f88ab580 00000880 f594ef30 c026abf8 c03a85df 000000a4 f88ab780 f594ef40 f8864218 f88ab780 00000000 f594ef48 f88a90f8 f594ef50 f88a91c9 f594efb0 c013cee1 73757361 70616c5f 00706f74 c015c10a 00000004 Call Trace: [<c0107ee3>] show_trace_log_lvl+0x1a/0x2f [<c0107f95>] show_stack_log_lvl+0x9d/0xa5 [<c010816a>] show_registers+0x1cd/0x2e3 [<c010839d>] die+0x11d/0x218 [<c032d2f9>] do_page_fault+0x511/0x5e9 [<c032bae2>] error_code+0x6a/0x70 [<c026abf8>] device_unregister+0x26/0x32 [<f8864218>] led_classdev_unregister+0x58/0x94 [led_class] [<f88a90f8>] asus_led_exit+0x17/0x41 [asus_laptop] [<f88a91c9>] asus_laptop_exit+0xd/0x3f [asus_laptop] [<c013cee1>] sys_delete_module+0x17b/0x1a2 [<c0106eae>] sysenter_past_esp+0x6b/0xa1 ======================= Code: 8b 56 04 89 d8 e8 10 fb ff ff 85 ff 74 0d 8b 97 d0 00 00 00 89 d8 e8 9d ff ff ff 5b 5e 5f 5d c3 55 89 e5 57 56 53 89 c3 83 ec 04 <8b> 40 64 85 c0 89 45 f0 74 08 8d 43 10 e8 e0 ee 0b 00 8b 83 20 EIP: [<c026a9a3>] device_del+0xb/0x23a SS:ESP 0068:f594ef0c Signed-off-by: Guillaume Chazarain <guichaz@xxxxxxxx> --- diff -r 1559df81a153 drivers/misc/asus-laptop.c --- a/drivers/misc/asus-laptop.c Mon Aug 13 05:00:33 2007 +0000 +++ b/drivers/misc/asus-laptop.c Tue Aug 14 13:06:40 2007 +0200 @@ -1072,7 +1072,8 @@ static void asus_backlight_exit(void) } #define ASUS_LED_UNREGISTER(object) \ - led_classdev_unregister(&object##_led) + if (object##_led.dev) \ + led_classdev_unregister(&object##_led) static void asus_led_exit(void) { -- Guillaume - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html