3.15-rc5 freeze after wakeup
From: Belisko Marek
Date: Sat May 17 2014 - 16:02:27 EST
Hi,
I've upgraded kernel on my PC to 3.15-rc5 and I got today freeze
(recovery possibly only by power off/on) when waking from suspend.
There is only warning in log but system was completely dead (no keys
reaction ....).
May 14 15:53:15 nb kernel: [30404.485085] PM: Syncing filesystems ... done.
May 14 15:53:15 nb kernel: [30404.711342] PM: Preparing system for mem sleep
May 14 15:53:15 nb kernel: [30404.711610] Freezing user space
processes ... (elapsed 0.001 seconds) done.
May 14 15:53:15 nb kernel: [30404.713305] Freezing remaining freezable
tasks ... (elapsed 0.001 seconds) done.
May 14 15:53:15 nb kernel: [30404.714431] PM: Entering mem sleep
May 14 15:53:15 nb kernel: [30404.714881] Suspending console(s) (use
no_console_suspend to debug)
May 14 15:53:15 nb kernel: [30405.338766] sd 4:0:0:0: [sda]
Synchronizing SCSI cache
May 14 15:53:15 nb kernel: [30405.338893] sd 4:0:0:0: [sda] Stopping disk
May 14 15:53:15 nb kernel: [30405.361653] nouveau [ DRM] evicting
buffers...
May 14 15:53:15 nb kernel: [30405.361654] nouveau [ DRM] waiting
for kernel channels to go idle...
May 14 15:53:15 nb kernel: [30405.361679] nouveau [ DRM]
suspending client object trees...
May 14 15:53:15 nb kernel: [30405.365746] ------------[ cut here ]------------
May 14 15:53:15 nb kernel: [30405.365765] WARNING: CPU: 1 PID: 21060
at drivers/gpu/drm/i915/intel_uncore.c:125
gen6_gt_check_fifodbg.isra.9+0x38/0x50 [i915]()
May 14 15:53:15 nb kernel: [30405.365765] MMIO read or write has been
dropped ffffffff
May 14 15:53:15 nb kernel: [30405.365782] Modules linked in:
cdc_acm(F) mmc_block(F) pl2303(F) usbserial(F) usblp(F) usb_storage(F)
ctr(F) ccm(F) rfcomm(F) bnep(F) snd_hda_codec_hdmi(F)
x86_pkg_temp_thermal(F) intel_powerclamp(F) coretemp(F) kvm(F)
uvcvideo(F) arc4(F) videobuf2_vmalloc(F) videobuf2_memops(F)
videobuf2_core(F) crct10dif_pclmul(F) crc32_pclmul(F)
ghash_clmulni_intel(F) nfsd(F) aesni_intel(F) iwlmvm(F) videodev(F)
i915(F) aes_x86_64(F) lrw(F) gf128mul(F) glue_helper(F) mac80211(F)
auth_rpcgss(F) nfs_acl(F) ablk_helper(F) cryptd(F) nouveau(F)
snd_hda_codec_realtek(F) snd_hda_intel(F) joydev(F) snd_hda_codec(F)
ttm(F) drm_kms_helper(F) snd_hwdep(F) snd_pcm(F) snd_page_alloc(F)
snd_seq_midi(F) asus_nb_wmi(F) iwlwifi(F) drm(F) snd_seq_midi_event(F)
nfs(F) snd_rawmidi(F) snd_seq(F) asus_wmi(F) sparse_keymap(F)
mxm_wmi(F) snd_seq_device(F) btusb(F) i2c_algo_bit(F) mei_me(F)
snd_timer(F) bluetooth(F) snd(F) cfg80211(F) lockd(F) sunrpc(F) mei(F)
soundcore(F) microcode(F) rtsx_pci_ms(F) memstick(F) binfmt_misc(F)
lpc_ich(F) fscache(F) psmouse(F) video(F) wmi(F) mac_hid(F)
serio_raw(F) nls_iso8859_1(F) parport_pc(F) ppdev(F) lp(F) parport(F)
rtsx_pci_sdmmc(F) ahci(F) r8169(F) libahci(F) rtsx_pci(F) mii(F)
May 14 15:53:15 nb kernel: [30405.365795] CPU: 1 PID: 21060 Comm:
kworker/u16:16 Tainted: GF W 3.13.2 #5
May 14 15:53:15 nb kernel: [30405.365796] Hardware name: ASUSTeK
COMPUTER INC. N56JR/N56JR, BIOS N56JR.204 10/31/2013
May 14 15:53:15 nb kernel: [30405.365804] Workqueue: i915
gen6_force_wake_work [i915]
May 14 15:53:15 nb kernel: [30405.365806] 0000000000000009
ffff88032964bd38 ffffffff81715b4e ffff88032964bd80
May 14 15:53:15 nb kernel: [30405.365807] ffff88032964bd70
ffffffff8106420d ffff8800363c8020 ffff8800363c8028
May 14 15:53:15 nb kernel: [30405.365809] 0000000000000246
0000000000000000 0000000000000200 ffff88032964bdd0
May 14 15:53:15 nb kernel: [30405.365809] Call Trace:
May 14 15:53:15 nb kernel: [30405.365813] [<ffffffff81715b4e>]
dump_stack+0x45/0x56
May 14 15:53:15 nb kernel: [30405.365815] [<ffffffff8106420d>]
warn_slowpath_common+0x7d/0xa0
May 14 15:53:15 nb kernel: [30405.365817] [<ffffffff8106427c>]
warn_slowpath_fmt+0x4c/0x50
May 14 15:53:15 nb kernel: [30405.365820] [<ffffffff810125b6>] ?
__switch_to+0x126/0x4c0
May 14 15:53:15 nb kernel: [30405.365827] [<ffffffffa06d93d8>]
gen6_gt_check_fifodbg.isra.9+0x38/0x50 [i915]
May 14 15:53:15 nb kernel: [30405.365834] [<ffffffffa06d947b>]
__gen6_gt_force_wake_mt_put+0x2b/0x30 [i915]
May 14 15:53:15 nb kernel: [30405.365840] [<ffffffffa06d91a7>]
gen6_force_wake_work+0x37/0x50 [i915]
May 14 15:53:15 nb kernel: [30405.365842] [<ffffffff8107fef2>]
process_one_work+0x182/0x450
May 14 15:53:15 nb kernel: [30405.365843] [<ffffffff81080cb1>]
worker_thread+0x121/0x410
May 14 15:53:15 nb kernel: [30405.365845] [<ffffffff81080b90>] ?
rescuer_thread+0x3e0/0x3e0
May 14 15:53:15 nb kernel: [30405.365846] [<ffffffff81087962>]
kthread+0xd2/0xf0
May 14 15:53:15 nb kernel: [30405.365847] [<ffffffff81087890>] ?
kthread_create_on_node+0x190/0x190
May 14 15:53:15 nb kernel: [30405.365849] [<ffffffff817267fc>]
ret_from_fork+0x7c/0xb0
May 14 15:53:15 nb kernel: [30405.365850] [<ffffffff81087890>] ?
kthread_create_on_node+0x190/0x190
May 14 15:53:15 nb kernel: [30405.365851] ---[ end trace 19ed8523f865bf12 ]---
May 14 15:53:15 nb kernel: [30405.370091] nouveau [ DRM]
suspending kernel object tree...
May 14 15:53:15 nb kernel: [30405.666015]
[drm:hsw_unclaimed_reg_clear] *ERROR* Unknown unclaimed register
before writing to c7204
May 14 15:53:15 nb kernel: [30405.666018]
[drm:hsw_unclaimed_reg_check] *ERROR* Unclaimed write to c7204
May 14 15:53:15 nb kernel: [30406.422806] PM: suspend of devices
complete after 1083.317 msecs
May 14 15:53:15 nb kernel: [30406.422960] PM: late suspend of devices
complete after 0.153 msecs
May 14 15:53:15 nb kernel: [30406.423102] pcieport 0000:00:1c.3:
System wakeup enabled by ACPI
May 14 15:53:15 nb kernel: [30406.454741] ehci-pci 0000:00:1d.0:
System wakeup enabled by ACPI
May 14 15:53:15 nb kernel: [30406.458786] ehci-pci 0000:00:1a.0:
System wakeup enabled by ACPI
May 14 15:53:15 nb kernel: [30406.466683] xhci_hcd 0000:00:14.0:
System wakeup enabled by ACPI
May 14 15:53:15 nb kernel: [30406.470879] PM: noirq suspend of devices
complete after 47.878 msecs
May 14 15:53:15 nb kernel: [30406.471095] ACPI: Preparing to enter
system sleep state S3
May 14 15:53:15 nb kernel: [30406.479514] PM: Saving platform NVS memory
May 14 15:53:15 nb kernel: [30406.487171] Disabling non-boot CPUs ...
May 14 15:53:15 nb kernel: [30406.590759] smpboot: CPU 1 is now offline
May 14 15:53:15 nb kernel: [30406.694832] smpboot: CPU 2 is now offline
May 14 15:53:15 nb kernel: [30406.798918] smpboot: CPU 3 is now offline
May 14 15:53:15 nb kernel: [30406.903000] smpboot: CPU 4 is now offline
May 14 15:53:15 nb kernel: [30406.903325] Broke affinity for irq 45
May 14 15:53:15 nb kernel: [30407.007082] smpboot: CPU 5 is now offline
May 14 15:53:15 nb kernel: [30407.007366] Broke affinity for irq 23
May 14 15:53:15 nb kernel: [30407.111168] smpboot: CPU 6 is now offline
May 14 15:53:15 nb kernel: [30407.215250] smpboot: CPU 7 is now offline
May 14 15:53:15 nb kernel: [30407.218003] ACPI: Low-level resume complete
May 14 15:53:15 nb kernel: [30407.218075] PM: Restoring platform NVS memory
May 14 15:53:15 nb kernel: [30407.222985] Enabling non-boot CPUs ...
May 14 15:53:15 nb kernel: [30407.223053] x86: Booting SMP configuration:
May 14 15:53:15 nb kernel: [30407.223056] smpboot: Booting Node 0
Processor 1 APIC 0x2
May 14 15:53:15 nb kernel: [30407.238540] Intel pstate controlling: cpu 1
May 14 15:53:15 nb kernel: [30407.238632] CPU1 is up
May 14 15:53:15 nb kernel: [30407.238683] smpboot: Booting Node 0
Processor 2 APIC 0x4
May 14 15:53:15 nb kernel: [30407.254230] Intel pstate controlling: cpu 2
May 14 15:53:15 nb kernel: [30407.254309] CPU2 is up
May 14 15:53:15 nb kernel: [30407.254340] smpboot: Booting Node 0
Processor 3 APIC 0x6
May 14 15:53:15 nb kernel: [30407.269887] Intel pstate controlling: cpu 3
May 14 15:53:15 nb kernel: [30407.269957] CPU3 is up
May 14 15:53:15 nb kernel: [30407.269989] smpboot: Booting Node 0
Processor 4 APIC 0x1
May 14 15:53:15 nb kernel: [30407.285600] Intel pstate controlling: cpu 4
May 14 15:53:15 nb kernel: [30407.285682] CPU4 is up
May 14 15:53:15 nb kernel: [30407.285716] smpboot: Booting Node 0
Processor 5 APIC 0x3
May 14 15:53:15 nb kernel: [30407.301231] Intel pstate controlling: cpu 5
May 14 15:53:15 nb kernel: [30407.301307] CPU5 is up
May 14 15:53:15 nb kernel: [30407.301339] smpboot: Booting Node 0
Processor 6 APIC 0x5
May 14 15:53:15 nb kernel: [30407.317032] Intel pstate controlling: cpu 6
May 14 15:53:15 nb kernel: [30407.317109] CPU6 is up
May 14 15:53:15 nb kernel: [30407.317141] smpboot: Booting Node 0
Processor 7 APIC 0x7
May 14 15:53:15 nb kernel: [30407.332847] Intel pstate controlling: cpu 7
May 14 15:53:15 nb kernel: [30407.332927] CPU7 is up
May 14 15:53:15 nb kernel: [30407.366387] ACPI: Waking up from system
sleep state S3
May 14 15:53:15 nb kernel: [30407.398885] xhci_hcd 0000:00:14.0:
System wakeup disabled by ACPI
May 14 15:53:15 nb kernel: [30407.406891] ehci-pci 0000:00:1a.0:
System wakeup disabled by ACPI
May 14 15:53:15 nb kernel: [30407.414890] ehci-pci 0000:00:1d.0:
System wakeup disabled by ACPI
May 14 15:53:15 nb kernel: [30407.494986] PM: noirq resume of devices
complete after 118.924 msecs
May 14 15:53:15 nb kernel: [30407.495106] PM: early resume of devices
complete after 0.100 msecs
May 14 15:53:15 nb kernel: [30407.495178] usb usb3: root hub lost
power or was reset
May 14 15:53:15 nb kernel: [30407.495178] usb usb4: root hub lost
power or was reset
May 14 15:53:15 nb kernel: [30407.495180] nouveau [ DRM]
re-enabling device...
May 14 15:53:15 nb kernel: [30407.495193] nouveau [ DRM] resuming
kernel object tree...
May 14 15:53:15 nb kernel: [30407.495198] nouveau [
VBIOS][0000:01:00.0] running init tables
May 14 15:53:15 nb kernel: [30407.495221] pcieport 0000:00:1c.3:
System wakeup disabled by ACPI
May 14 15:53:15 nb kernel: [30407.495229] snd_hda_intel 0000:00:03.0:
irq 43 for MSI/MSI-X
May 14 15:53:15 nb kernel: [30407.495237] iwlwifi 0000:03:00.0:
RF_KILL bit toggled to enable radio.
May 14 15:53:15 nb kernel: [30407.495796] xhci_hcd 0000:00:14.0: irq
47 for MSI/MSI-X
May 14 15:53:15 nb kernel: [30407.498912] mei_me 0000:00:16.0: irq 49
for MSI/MSI-X
May 14 15:53:15 nb kernel: [30407.498991] snd_hda_intel 0000:00:1b.0:
irq 52 for MSI/MSI-X
May 14 15:53:15 nb kernel: [30407.640399] nouveau [
VOLT][0000:01:00.0] GPU voltage: 600000uv
May 14 15:53:15 nb kernel: [30407.640401] nouveau [
PTHERM][0000:01:00.0] fan management: automatic
May 14 15:53:15 nb kernel: [30407.640479] nouveau [
CLK][0000:01:00.0] --: core 405 MHz memory 405 MHz
May 14 15:53:15 nb kernel: [30407.645897] nouveau [ DRM] resuming
client object trees...
May 14 15:53:15 nb kernel: [30407.723085] usb 2-1: reset high-speed
USB device number 2 using ehci-pci
May 14 15:53:15 nb kernel: [30407.819158] ata3: SATA link up 1.5 Gbps
(SStatus 113 SControl 300)
May 14 15:53:15 nb kernel: [30407.967271] usb 1-1: reset high-speed
USB device number 2 using ehci-pci
May 14 15:53:15 nb kernel: [30408.211470] usb 3-5: reset full-speed
USB device number 5 using xhci_hcd
May 14 15:53:15 nb kernel: [30408.228022] xhci_hcd 0000:00:14.0: xHCI
xhci_drop_endpoint called with disabled ep ffff880416844840
May 14 15:53:15 nb kernel: [30408.228023] xhci_hcd 0000:00:14.0: xHCI
xhci_drop_endpoint called with disabled ep ffff880416844880
May 14 15:53:15 nb kernel: [30408.228024] xhci_hcd 0000:00:14.0: xHCI
xhci_drop_endpoint called with disabled ep ffff8804168448c0
May 14 15:53:15 nb kernel: [30408.228026] xhci_hcd 0000:00:14.0: xHCI
xhci_drop_endpoint called with disabled ep ffff8800360c9c80
May 14 15:53:15 nb kernel: [30408.228027] xhci_hcd 0000:00:14.0: xHCI
xhci_drop_endpoint called with disabled ep ffff8800360c9cc0
May 14 15:53:15 nb kernel: [30408.236873] ata3.00: configured for UDMA/100
May 14 15:53:15 nb kernel: [30408.339607] usb 3-7: reset high-speed
USB device number 3 using xhci_hcd
May 14 15:53:15 nb kernel: [30408.444647] xhci_hcd 0000:00:14.0: xHCI
xhci_drop_endpoint called with disabled ep ffff88041382e040
May 14 15:53:15 nb kernel: [30408.791920] [drm] Enabling RC6 states:
RC6 on, RC6p off, RC6pp off
May 14 15:53:15 nb kernel: [30409.508485] ata5: SATA link up 6.0 Gbps
(SStatus 133 SControl 300)
May 14 15:53:15 nb kernel: [30409.718603] ata5.00: ACPI cmd
ef/10:06:00:00:00:00 (SET FEATURES) succeeded
May 14 15:53:15 nb kernel: [30409.718604] ata5.00: ACPI cmd
f5/00:00:00:00:00:00 (SECURITY FREEZE LOCK) filtered out
May 14 15:53:15 nb kernel: [30409.718606] ata5.00: ACPI cmd
b1/c1:00:00:00:00:00 (DEVICE CONFIGURATION OVERLAY) filtered out
May 14 15:53:15 nb kernel: [30409.755067] ata5.00: ACPI cmd
ef/10:06:00:00:00:00 (SET FEATURES) succeeded
May 14 15:53:15 nb kernel: [30409.755068] ata5.00: ACPI cmd
f5/00:00:00:00:00:00 (SECURITY FREEZE LOCK) filtered out
May 14 15:53:15 nb kernel: [30409.755069] ata5.00: ACPI cmd
b1/c1:00:00:00:00:00 (DEVICE CONFIGURATION OVERLAY) filtered out
May 14 15:53:15 nb kernel: [30409.759979] ata5.00: configured for UDMA/133
May 14 15:53:15 nb kernel: [30409.772791] sd 4:0:0:0: [sda] Starting disk
May 14 15:53:15 nb kernel: [30409.786025] PM: resume of devices
complete after 2289.069 msecs
May 14 15:53:15 nb kernel: [30409.786617] PM: Finishing wakeup.
May 14 15:53:15 nb kernel: [30409.786618] Restarting tasks ... done.
May 14 15:53:15 nb kernel: [30409.796847] video LNXVIDEO:00: Restoring
backlight state
May 14 15:53:15 nb kernel: [30409.796850] video LNXVIDEO:01: Restoring
backlight state
May 14 15:53:15 nb kernel: [30409.803648] Bluetooth: hci0: read Intel
version: 370710018002030d00
May 14 15:53:15 nb kernel: [30409.803653] Bluetooth: hci0: Intel
Bluetooth firmware file: intel/ibt-hw-37.7.10-fw-1.80.2.3.d.bseq
May 14 15:53:15 nb kernel: [30409.954771] Bluetooth: hci0: Intel
Bluetooth firmware patch completed and activated
May 14 15:53:16 nb kernel: [30410.341420] iwlwifi 0000:03:00.0: L1
Disabled; Enabling L0S
May 14 15:53:16 nb kernel: [30410.341670] iwlwifi 0000:03:00.0: L1
Disabled; Enabling L0S
May 14 15:53:16 nb kernel: [30410.353518] IPv6: ADDRCONF(NETDEV_UP):
wlan0: link is not ready
May 14 15:53:16 nb kernel: [30410.415374] r8169 0000:04:00.0 eth0: link down
May 14 15:53:16 nb kernel: [30410.415442] IPv6: ADDRCONF(NETDEV_UP):
eth0: link is not ready
May 14 15:53:20 nb kernel: [30414.808849] ACPI Warning:
\_SB_.PCI0.PEG0.PEGP._DSM: Argument #4 type mismatch - Found [Buffer],
ACPI requires [Package] (20131115/nsarguments-95)
May 14 15:53:20 nb kernel: [30414.809147] ACPI Warning:
\_SB_.PCI0.PEG0.PEGP._DSM: Argument #4 type mismatch - Found [Buffer],
ACPI requires [Package] (20131115/nsarguments-95)
May 14 15:53:23 nb kernel: [30417.496653] wlan0: authenticate with
00:1f:c6:e8:34:e8
May 14 15:53:23 nb kernel: [30417.498323] wlan0: send auth to
00:1f:c6:e8:34:e8 (try 1/3)
May 14 15:53:23 nb kernel: [30417.500155] wlan0: authenticated
May 14 15:53:23 nb kernel: [30417.500276] iwlwifi 0000:03:00.0 wlan0:
disabling HT as WMM/QoS is not supported by the AP
May 14 15:53:23 nb kernel: [30417.500278] iwlwifi 0000:03:00.0 wlan0:
disabling VHT as WMM/QoS is not supported by the AP
May 14 15:53:23 nb kernel: [30417.502965] wlan0: associate with
00:1f:c6:e8:34:e8 (try 1/3)
May 14 15:53:23 nb kernel: [30417.508008] wlan0: RX AssocResp from
00:1f:c6:e8:34:e8 (capab=0x411 status=0 aid=2)
May 14 15:53:23 nb kernel: [30417.509332] wlan0: associated
May 14 15:53:23 nb kernel: [30417.509365] IPv6:
ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
May 14 15:53:23 nb kernel: [30417.532755] wlan0: deauthenticating from
00:1f:c6:e8:34:e8 by local choice (reason=2)
May 14 15:53:23 nb kernel: [30417.535435] wlan0: authenticate with
00:1f:c6:e8:34:e8
May 14 15:53:23 nb kernel: [30417.537373] wlan0: send auth to
00:1f:c6:e8:34:e8 (try 1/3)
May 14 15:53:23 nb kernel: [30417.537616] cfg80211: Calling CRDA to
update world regulatory domain
May 14 15:53:23 nb kernel: [30417.539571] cfg80211: World regulatory
domain updated:
May 14 15:53:23 nb kernel: [30417.539573] cfg80211: (start_freq -
end_freq @ bandwidth), (max_antenna_gain, max_eirp)
May 14 15:53:23 nb kernel: [30417.539574] cfg80211: (2402000 KHz -
2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
May 14 15:53:23 nb kernel: [30417.539575] cfg80211: (2457000 KHz -
2482000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
May 14 15:53:23 nb kernel: [30417.539576] cfg80211: (2474000 KHz -
2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm)
May 14 15:53:23 nb kernel: [30417.539577] cfg80211: (5170000 KHz -
5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
May 14 15:53:23 nb kernel: [30417.539577] cfg80211: (5735000 KHz -
5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm)
May 14 15:53:23 nb kernel: [30417.542460] wlan0: authenticated
May 14 15:53:23 nb kernel: [30417.542587] iwlwifi 0000:03:00.0 wlan0:
disabling HT as WMM/QoS is not supported by the AP
May 14 15:53:23 nb kernel: [30417.542589] iwlwifi 0000:03:00.0 wlan0:
disabling VHT as WMM/QoS is not supported by the AP
May 14 15:53:23 nb kernel: [30417.542978] wlan0: associate with
00:1f:c6:e8:34:e8 (try 1/3)
May 14 15:53:23 nb kernel: [30417.546598] wlan0: RX AssocResp from
00:1f:c6:e8:34:e8 (capab=0x411 status=0 aid=2)
May 14 15:53:23 nb kernel: [30417.551141] wlan0: associated
May 14 16:27:32 nb kernel: [32470.315421] audit_printk_skb: 57
callbacks suppressed
May 14 16:27:32 nb kernel: [32470.315424] type=1400
audit(1400077652.391:80): apparmor="STATUS"
operation="profile_replace" name="/usr/lib/cups/backend/cups-pdf"
pid=22382 comm="apparmor_parser"
May 14 16:27:32 nb kernel: [32470.315427] type=1400
audit(1400077652.391:81): apparmor="STATUS"
operation="profile_replace" name="/usr/sbin/cupsd" pid=22382
comm="apparmor_parser"
May 14 16:27:32 nb kernel: [32470.315658] type=1400
audit(1400077652.391:82): apparmor="STATUS"
operation="profile_replace" name="/usr/sbin/cupsd" pid=22382
comm="apparmor_parser"
BR,
marek
--
as simple and primitive as possible
-------------------------------------------------
Marek Belisko - OPEN-NANDRA
Freelance Developer
Ruska Nova Ves 219 | Presov, 08005 Slovak Republic
Tel: +421 915 052 184
skype: marekwhite
twitter: #opennandra
web: http://open-nandra.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/