EEE PC hangs when booting off battery

Alan Jenkins wrote:
Alan Jenkins wrote:

Bjorn Helgaas wrote:


On Tuesday 14 April 2009 09:17:28 am Arjan van de Ven wrote:



On Tue, 14 Apr 2009 08:59:01 -0600
Bjorn Helgaas <bjorn.helgaas@xxxxxx> wrote:




I can't help with the real problem of why the asynchronous battery
init causes the hang.



that got fixed already for the module case.



But apparently still broken for the builtin case? I think Alan is
running pretty new bits -- he said "latest git" on April 11.



It's now fixed, in 2.6.30-rc2. My battery is modular btw. I suspect

5d38258ec026921a7b266f4047ebeaa75db358e5 "ACPI battery: fix async boot
oops" [removal of __init]

was not sufficient to fix my problem, but it was solved by the "real" fix,

d6de2c80e9d758d2e36c21699117db6178c0f517 "async: Fix module loading
async-work regression" [module loading waits on async work]


I would argue there's still a question over why the asynchronous battery
init (_with_ the oops fix) should cause a hang in the idle routine. But
since the regression is fixed, it's not exactly an urgent question.



Ugh. Recently I tried building the battery driver into the kernel, to
benefit from the async work. Later, I tried booting from the battery
and it hung again.

This time, the kernel did not even respond to SysRq. I tried
nmi_watchdog=1 and waiting 2 minutes, but the watchdog didn't trigger
either. As before, it doesn't happen with acpi=off.

I checked that this still happened in todays rc3, and it doesn't happen
if I revert

0f66af530116e9f4dd97f328d91718b56a6fc5a4 "ACPI: battery: asynchronous init"



It looks like my hang is caused by linkwatch_event() deadlocking on
rtnl_lock(). I can't see any direct connection to asynchronous battery
init, so perhaps that is just revealing a bug by changing the timing.

It appears I wasn't patient enough for hung task detection. If I leave
it long enough, I see:

<scrolled off top of screen>
? kobject_uevent_env
? kobject_uevent_env
__mutex_lock_slowpath
mutex_lock
rtnl_lock
linkwatch_event
worker_thread
? linkwatch_event
? autoremove_wake_function
? worker_thread
kthread
kernel_thread_helper


INFO: task modprobe:485 blocked for more than 120 seconds
Call trace:
? __atomic_notifier_call_chain
schedule
schedule_timeout
? notify_update
? do_con_write
? __wake_up
wait_for_common
? default_wake_function
wait_for_completion
flush_cpu_workqueue
? wq_barrier_func
flush_workqueue
flush_scheduled_work
tty_ldisc_release
? tty_fasyc
tty_release_dev
? free_pgtables
tty_release
__fput
filp_close
sys_close
syscall_call
? __send_remote_softirq
? usecs_to_jiffies


I then seem to get another repetition of the second calltrace, followed
by a new one

INFO: task swapper:1 blocked for more than 120 seconds
Call trace:
schedule
schedule_timeout
? __wake_up_common
? wake_up
wait_for_common
wait_for_completion
call_usermodehelper_exec
__request_module
crypto_larval_lookup
? extract_entropy
crypto_alg_mod_lookup
crypto_alloc_base
ieee80211_wep_init
ieee80211_register_hw
? ath5k_hw_set_bss
ath5k+pci_probe
local_pci_probe
pci_device_probe
driver_probe_device
__driver_attach
bus_for_each_dev
driver_attach
? __driver_attach
buad_add_driver
driver_register
? ktime_get_ts
__pci_register_driver
init_ath5k_pci
_stext
? init_ath5k_pci
? proc_create_data
? register_ieq_proc
kernel_init
? kernel_init
kernel_thread_helper




The hang happens at this point:

[ 0.967588] scsi 1:0:0:0: Direct-Access ATA SILICONMOTION SM
n/a PQ: 0 ANSI: 5
[ 0.968049] calling 4_sd_probe_async+0x0/0x225 @ 323
[ 0.968313] initcall 3_async_port_probe+0x0/0x95 returned 0 after
343051 usecs
<mark> (see below).
[ 0.968786] sd 1:0:0:0: [sda] 7815024 512-byte hardware sectors:
(4.00 GB/3.72 GiB)
[ 0.968964] sd 1:0:0:0: [sda] Write Protect is off
[ 0.969062] sd 1:0:0:0: [sda] Mode Sense: 00 3a 00 00
[ 0.969132] sd 1:0:0:0: [sda] Write cache: disabled, read cache:
enabled, doesn't support DPO or FUA
[ 0.969543] sda: sda1 sda2
[ 0.970965] sd 1:0:0:0: [sda] Attached SCSI disk
[ 0.971073] initcall 4_sd_probe_async+0x0/0x225 returned 0 after 2849
usecs

On a successful boot, the next lines are

[ 0.971188] async_continuing @ 1 after 2483 usec
[ 0.971305] Freeing unused kernel memory: 256k freed
[ 1.071724] calling ata_generic_init+0x0/0x19 [ata_generic] @ 574
[ 1.073798] initcall ata_generic_init+0x0/0x19 [ata_generic] returned
0 after 144 usecs
[ 1.183372] Clocksource tsc unstable (delta = -128600689 ns)
[ 2.035932] EXT4-fs: delayed allocation enabled

Also, on a successful boot, I see these additional lines at the point
<mark> above.

[ 0.968461] async_continuing @ 1 after 76663 usec
[ 0.968556] async_waiting @ 1

In fact, when the hang happens I can see no "async_waiting @ 1" on my
50-line screen. Which makes sense if the kernel init process is hung
in init_athk_pci().


Thanks
Alan
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