Re: [crash] BUG: unable to handle kernel NULL pointer dereference at 0000000000000370

Larry Finger
2008-07-21T19:43:47Z

Ingo Molnar wrote:
> * Larry Finger <Larry.Finger@lwfinger.net> wrote:
>
>> Ingo Molnar wrote:
>>> * Ian Schram <ischram@telenet.be> wrote:
>>>
>>>> I was looking at this out of interest, but I'm in no way familiar
>>>> with the code.
>>> thanks Ian for the patch, i'll test it.
>>>
>>> Note that it was whitespace damaged, find below a tidied up version of
>>> the patch that i've applied to tip/out-of-tree.
>>>
>>> Ingo
>> This patch may be needed to fix error handling in the hw_sim code, but
>> I get the crash even with that code disabled. I'm currently bisecting
>> to find the culprit.
>
> ok. I just reactivated CONFIG_MAC80211_HWSIM, applied Ian's fix and the
> crash went away:
>
> calling iwl4965_init+0x0/0x6c
> iwl4965: Intel(R) Wireless WiFi Link 4965AGN driver for Linux, 1.3.27kd
> iwl4965: Copyright(c) 2003-2008 Intel Corporation
> initcall iwl4965_init+0x0/0x6c returned 0 after 10 msecs
> calling init_mac80211_hwsim+0x0/0x31c
> mac80211_hwsim: Initializing radio 0
> PM: Adding info for No Bus:hwsim0
> PM: Adding info for No Bus:phy0
> PM: Adding info for No Bus:wmaster0
> phy0: Failed to select rate control algorithm
> phy0: Failed to initialize rate control algorithm
> PM: Removing info for No Bus:wmaster0
> PM: Removing info for No Bus:phy0
> mac80211_hwsim: ieee80211_register_hw failed (-2)
> PM: Removing info for No Bus:hwsim0
> initcall init_mac80211_hwsim+0x0/0x31c returned -2 after 58 msecs
> initcall init_mac80211_hwsim+0x0/0x31c returned with error code -2
> calling dmfe_init_module+0x0/0xea
> dmfe: Davicom DM9xxx net driver, version 1.36.4 (2002-01-17)
> initcall dmfe_init_module+0x0/0xea returned 0 after 5 msecs
>
> So at least as far as the init_mac80211_hwsim() deinit crash goes:
>
> Tested-by: Ingo Molnar <mingo@elte.hu>

Yes, I'm chasing a distinct bug. The header for mine is

Jul 21 12:19:37 larrylap kernel: kernel BUG at net/core/dev.c:1328!
Jul 21 12:19:37 larrylap kernel: invalid opcode: 0000 [1] SMP
Jul 21 12:19:37 larrylap kernel: CPU 0
Jul 21 12:19:37 larrylap kernel: Modules linked in: af_packet rfkill_input nfs
lockd nfs_acl sunrpc cpufreq_conservative cpu
freq_userspace cpufreq_powersave powernow_k8 fuse loop dm_mod arc4 ecb
crypto_blkcipher b43 firmware_class rfkill mac80211 c
fg80211 snd_hda_intel snd_pcm snd_timer led_class snd k8temp input_polldev
sr_mod soundcore button battery hwmon cdrom force
deth ac serio_raw ssb snd_page_alloc sg ehci_hcd sd_mod ohci_hcd usbcore edd fan
thermal processor ext3 mbcache jbd pata_amd
ahci libata scsi_mod dock
Jul 21 12:19:37 larrylap kernel: Pid: 2057, comm: b43 Not tainted
2.6.26-Linus-git-05253-g14b395e #1
Jul 21 12:19:37 larrylap kernel: RIP: 0010:[<ffffffff8039ec4d>]
[<ffffffff8039ec4d>] __netif_schedule+0x12/0x75
Jul 21 12:19:37 larrylap kernel: RSP: 0000:ffff8800b9ae1de0 EFLAGS: 00010246

With an invalid opcode, mine is likely due to stack corruption.

Larry