So I've had a chance to do some testing. I can reliably generate then following trace with daniels patch on 3.2-rt10
[ 188.561901] ------------[ cut here ]------------ [ 188.561908] WARNING: at fs/proc/generic.c:586 proc_register+0x181/0x1c7() [ 188.561909] Hardware name: HP Compaq 6910p [ 188.561911] proc_dir_entry 'card1/pcm0p' already registered [ 188.561912] Modules linked in: snd_usb_audio snd_usbmidi_lib snd_seq_dummy acpi_cpufreq mperf cpufreq_userspace cpufreq_stats cpufreq_conservative cpufreq_powersave ppdev lp parport microcode binfmt_misc uinput fuse nfsd exportfs nfs lockd fscache auth_rpcgss nfs_acl sunrpc ext2 firewire_sbp2 loop btusb bluetooth snd_hda_codec_analog arc4 iwl4965 iwl_legacy i915 mac80211 uhci_hcd snd_hda_intel snd_hda_codec ehci_hcd drm_kms_helper snd_hwdep drm snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_midi cfg80211 snd_rawmidi snd_seq_midi_event snd_seq usbcore sr_mod mmc_block snd_timer tpm_infineon pata_pcmcia snd_seq_device firewire_ohci snd sdhci_pci i2c_algo_bit irda cdrom sdhci joydev pcmcia tpm_tis ata_generic ata_piix hp_wmi firewire_core i2c_core yenta_socket pcmcia_rsrc iTCO_wdt mmc_core battery pcmcia_core sparse_keymap ac power_supply rfkill pcspkr soundcore tpm tpm_bios wmi iTCO_vendor_support evdev crc_itu_t crc_ccitt psmouse processor container video usb_common snd_page_alloc serio_raw button ext3 jbd mbcache sha256_generic aes_x86_64 aes_generic cbc dm_crypt dm_mod sd_mod crc_t10dif ahci libahci libata scsi_mod fan thermal thermal_sys [ 188.561979] Pid: 621, comm: khubd Not tainted 3.2.0-rt10-00255-g530565d #5 [ 188.561980] Call Trace: [ 188.561986] [<ffffffff81036273>] ? warn_slowpath_common+0x78/0x8c [ 188.561989] [<ffffffff8103631f>] ? warn_slowpath_fmt+0x45/0x4a [ 188.561993] [<ffffffff8102df06>] ? get_parent_ip+0x9/0x1b [ 188.561995] [<ffffffff81123ac5>] ? proc_register+0x181/0x1c7 [ 188.561997] [<ffffffff81123e2c>] ? create_proc_entry+0x6e/0x85 [ 188.562020] [<ffffffffa0237c18>] ? snd_info_register+0x35/0xbd [snd] [ 188.562026] [<ffffffffa02cdf89>] ? snd_pcm_new_stream+0xd6/0x417 [snd_pcm] [ 188.562031] [<ffffffffa05b69e3>] ? snd_usb_add_audio_stream+0xd5/0x21c [snd_usb_audio] [ 188.562035] [<ffffffffa05b6fd3>] ? snd_usb_parse_audio_interface+0x4a9/0x556 [snd_usb_audio] [ 188.562039] [<ffffffffa05ae276>] ? snd_usb_create_stream+0xed/0x126 [snd_usb_audio] [ 188.562043] [<ffffffffa05aea74>] ? usb_audio_probe+0x61d/0x72d [snd_usb_audio] [ 188.562057] [<ffffffffa028c6e3>] ? usb_probe_interface+0xf8/0x163 [usbcore] [ 188.562062] [<ffffffff812170f1>] ? driver_probe_device+0xa8/0x138 [ 188.562064] [<ffffffff812171f0>] ? __driver_attach+0x6f/0x6f [ 188.562066] [<ffffffff81216120>] ? bus_for_each_drv+0x4a/0x7e [ 188.562069] [<ffffffff81217012>] ? device_attach+0x6f/0x8f [ 188.562071] [<ffffffff8121692c>] ? bus_probe_device+0x1f/0x37 [ 188.562073] [<ffffffff8121520a>] ? device_add+0x3d4/0x577 [ 188.562076] [<ffffffff8102df06>] ? get_parent_ip+0x9/0x1b [ 188.562078] [<ffffffff81030bf0>] ? migrate_enable+0x150/0x16a [ 188.562085] [<ffffffffa028b2b0>] ? usb_set_configuration+0x53f/0x594 [usbcore] [ 188.562088] [<ffffffff811304e6>] ? sysfs_do_create_link+0x149/0x194 [ 188.562094] [<ffffffffa029231a>] ? generic_probe+0x45/0x73 [usbcore] [ 188.562097] [<ffffffff812170f1>] ? driver_probe_device+0xa8/0x138 [ 188.562099] [<ffffffff812171f0>] ? __driver_attach+0x6f/0x6f [ 188.562101] [<ffffffff81216120>] ? bus_for_each_drv+0x4a/0x7e [ 188.562104] [<ffffffff81217012>] ? device_attach+0x6f/0x8f [ 188.562106] [<ffffffff8121692c>] ? bus_probe_device+0x1f/0x37 [ 188.562108] [<ffffffff8121520a>] ? device_add+0x3d4/0x577 [ 188.562110] [<ffffffff81214793>] ? dev_printk+0x48/0x4d [ 188.562116] [<ffffffffa0285188>] ? usb_new_device+0x124/0x198 [usbcore] [ 188.562122] [<ffffffffa02861eb>] ? hub_thread+0x964/0xe54 [usbcore] [ 188.562124] [<ffffffff8102abf4>] ? hrtick_start_fair+0x1a/0x15b [ 188.562127] [<ffffffff8102000a>] ? kern_addr_valid+0x5/0x93 [ 188.562131] [<ffffffff8131adb9>] ? __schedule+0x531/0x548 [ 188.562135] [<ffffffff8104ff82>] ? __init_waitqueue_head+0x39/0x39 [ 188.562140] [<ffffffffa0285887>] ? usb_remote_wakeup+0x2f/0x2f [usbcore] [ 188.562142] [<ffffffff8104f8b8>] ? kthread+0x78/0x80 [ 188.562145] [<ffffffff8102df06>] ? get_parent_ip+0x9/0x1b [ 188.562148] [<ffffffff81310000>] ? init_amd+0x112/0x3e4 [ 188.562151] [<ffffffff81322d74>] ? kernel_thread_helper+0x4/0x10 [ 188.562154] [<ffffffff8104f840>] ? __init_kthread_worker+0x41/0x41 [ 188.562156] [<ffffffff81322d70>] ? gs_change+0x13/0x13 [ 188.562161] ---[ end trace 0000000000000002 ]---
Grant