Re: blk_mq_register_disk: kobject (00000000009f2dd8): tried to init an initialized object, something is seriously wrong.

[Meelis Roos <mroos@linux.ee>]

> On Sun, Oct 4, 2015 at 3:33 AM, Meelis Roos <mroos@linux.ee> wrote:
> >> This is 4.3.0-rc1 on Sun E220R (dual-CPU sparc64). Sometimes it boots,
> >> sometimes it fails to boot with looping errors and finally a watchdog
> >> timeout. This console log from a failure. Config is below.
> >
> > I noticed blk-mq related changes in todays git. Retested, loop_init
> > still causes the same blk-mq problem.
> 
> 
> > [  100.063323] blk_mq_sysfs_init: init hctx_kobj fffff800ad8b95f8 0
> > [  100.135151] blk_mq_sysfs_init: init ctx_kobj fffff800af80cdd8 0
> > [  100.205952] blk_mq_sysfs_init: init ctx_kobj 00000000009f2dd8 1
> > [  100.276785] kobject (00000000009f2dd8): tried to init an initialized object, something is seriously wrong.
> 
> >From the debug log, the issue happened on ctx_kobj which is one
> percpu variable, and looks it can't be initialized by blk-mq more than
> one time.
> 
> I suspect it may be one memory issue, especiall in percpu allocation.
> The percpu variable's address for the offline CPU1 is a bit special, not
> like the other two online CPUs. And it might be helpful to enalbe
> 'Per cpu operations test' in' Kernel hacking  --->'/'Runtime Testing'
> of Kconfig to see if it can pass the test.

Configure the precpu test module to be compiled, included it in 
/proc/modules before loop. Percpu test test fine - 4 successful boots 
and one failure, and the test finds nothing bad:

[  137.674383] percpu test start
[  137.709010] percpu test done
[  137.876170] kobject (00000000009fcdd8): tried to init an initialized object, something is seriously wrong.
[  137.990966] CPU: 2 PID: 1172 Comm: modprobe Tainted: G    B DA C   LK 4.3.0-rc3-00199-g978ab6a #69


-- 
Meelis Roos (mroos@linux.ee)