On Thu, Mar 12, 2015 at 3:45 PM, Greg KH <[email protected]> wrote: > On Thu, Mar 12, 2015 at 01:04:16PM +0900, Ethan Zhao wrote: >> call kobject_get() to kojbect that is not initalized or released will only >> leave following like call trace to us: >> >> -----------[ cut here ]------------ >> [ 54.545816] WARNING: CPU: 0 PID: 213 at include/linux/kref.h:47 >> kobject_get+0x41/0x50() >> [ 54.642595] Modules linked in: i2c_i801(+) mfd_core shpchp(+) >> acpi_cpufreq(+) edac_core ioatdma(+) xfs libcrc32c ast syscopyarea ixgbe >> sysfillrect sysimgblt sr_mod sd_mod drm_kms_helper igb mdio cdrom e1000e ahci >> dca ttm libahci uas drm i2c_algo_bit ptp megaraid_sas libata usb_storage >> i2c_core pps_core dm_mirror dm_region_hash dm_log dm_mod >> [ 55.007264] CPU: 0 PID: 213 Comm: kworker/0:2 Not tainted >> 3.18.5 >> [ 55.099970] Hardware name: Oracle Corporation SUN FIRE X4170 M2 SERVER >> /ASSY,MOTHERBOARD,X4170, BIOS 08120104 05/08/2012 >> [ 55.239736] Workqueue: kacpi_notify acpi_os_execute_deferred >> [ 55.308598] 0000000000000000 00000000bd730b61 ffff88046742baf8 >> ffffffff816b7edb >> [ 55.398305] 0000000000000000 0000000000000000 ffff88046742bb38 >> ffffffff81078ae1 >> [ 55.488040] ffff88046742bbd8 ffff8806706b3000 0000000000000292 >> 0000000000000000 >> [ 55.577776] Call Trace: >> [ 55.608228] [<ffffffff816b7edb>] dump_stack+0x46/0x58 >> [ 55.670895] [<ffffffff81078ae1>] warn_slowpath_common+0x81/0xa0 >> [ 55.743952] [<ffffffff81078bfa>] warn_slowpath_null+0x1a/0x20 >> [ 55.814929] [<ffffffff8130d0d1>] kobject_get+0x41/0x50 >> [ 55.878654] [<ffffffff8153e955>] cpufreq_cpu_get+0x75/0xc0 >> [ 55.946528] [<ffffffff8153f37e>] cpufreq_update_policy+0x2e/0x1f0 >> >> The above issue was casued by a race condition, if there is a WARN in >> kobject_get() of the kobject is not initialized, that would save us much >> time to debug it. >> >> Signed-off-by: Ethan Zhao <[email protected]> >> --- >> lib/kobject.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/lib/kobject.c b/lib/kobject.c >> index 03d4ab3..3b841b9 100644 >> --- a/lib/kobject.c >> +++ b/lib/kobject.c >> @@ -576,8 +576,13 @@ void kobject_del(struct kobject *kobj) >> */ >> struct kobject *kobject_get(struct kobject *kobj) >> { >> - if (kobj) >> + if (kobj) { >> + if (!kobj->state_initialized) >> + WARN(1, KERN_WARNING "kobject: '%s' (%p): is not " >> + "initialized, yet kobject_get() is being " >> + "called.\n", kobject_name(kobj), kobj); >> kref_get(&kobj->kref); >> + } >> return kobj; >> } >> > > Have you tried running a system with this patch to see if there are a > lot of messages at boot time? I'm a bit worried that the initial
Don't worry about that, no warning appear if no bug hit, I have tried booting the kernel with this patch hundreds of times (To verify another issue at the same time ). > kobject init sequence would trigger this, but haven't looked at the full > codepath just yet given that I haven't had my morning coffee... Enjoy your coffee. Thanks, Ethan > > thanks, > > greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
