Subject: Re: kernel panic in skb_copy_bits

From: Ben Greear <[email-masked]>
Date: Sat, 29 Jun 2013 09:11:15 -0700

On 06/29/2013 12:20 AM, Eric Dumazet wrote:
> On Sat, 2013-06-29 at 07:36 +0800, Joe Jin wrote:
>> Hi Eric,
>>
>> The patch not fix the issue and panic as same as early I posted:
>>> BUG: unable to handle kernel paging request at ffff88006d9e8d48
>>> IP: [<ffffffff812605bb>] memcpy+0xb/0x120
>>> PGD 1798067 PUD 1fd2067 PMD 213f067 PTE 0
>>> Oops: 0000 [#1] SMP
>>> CPU 7
>>> Modules linked in: dm_nfs tun nfs fscache auth_rpcgss nfs_acl xen_blkback xen_netback xen_gntdev xen_evtchn lockd sunrpc bridge stp llc bonding be2iscsi iscsi_boot_sysfs ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core ib_addr iscsi_tcp bnx2i cnic uio ipv6 cxgb3i libcxgbi cxgb3 mdio dm_round_robin dm_multipath libiscsi_tcp libiscsi scsi_transport_iscsi xenfs xen_privcmd video sbs sbshc acpi_memhotplug acpi_ipmi ipmi_msghandler parport_pc lp parport ixgbe dca sr_mod cdrom bnx2 radeon ttm drm_kms_helper drm snd_seq_dummy i2c_algo_bit i2c_core snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss serio_raw snd_pcm snd_timer snd soundcore snd_page_alloc iTCO_wdt pcspkr iTCO_vendor_support pata_acpi dcdbas i5k_amb ata_generic hwmon floppy ghes i5000_edac edac_core 
 hed dm_snapshot dm_zero dm_mirror dm_region_hash dm_log dm_mod usb_storage lpfc scsi_transport_fc scsi_tgt ata_piix sg shpchp mptsas mptscsih mptbase scsi_transport_sas sd_mod crc_t10dif ex!
 t3!
>>    jbd mbcac
>> he
>>>
>>>
>>> Pid: 0, comm: swapper Tainted: G        W   2.6.39-300.32.1.el5uek #1 Dell Inc. PowerEdge 2950/0DP246
>
>
> By the way my patch was for current kernels, not for 2.6.39

Do you know if your patch should go in 3.9?

Your test case sounds a bit like what gives us the rare crash in tcp_collapse
(we have lots of bouncing wifi interfaces running slow-speed TCP trafic).  But,
it takes days for us to hit the problem most of the time.

Thanks,
Ben

-- 
Ben Greear <[email-masked]>
Candela Technologies Inc  http://www.candelatech.com