From: Jens Axboe <jaxboe@fusionio.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.39-rc4 BUG: unable to handle kernel NULL pointer dereference at 0000000c IP: cfq_insert_request+0x1d/0x3f5
Date: Wed, 20 Apr 2011 15:31:53 +0200 [thread overview]
Message-ID: <4DAEE049.7050407@fusionio.com> (raw)
In-Reply-To: <20110420132903.GA13554@tiehlicka.suse.cz>
On 2011-04-20 15:29, Michal Hocko wrote:
> On Wed 20-04-11 15:13:15, Jens Axboe wrote:
>> On 2011-04-20 14:58, Michal Hocko wrote:
>>> Hi,
>>> I am not able to boot with the current git tree
>>> (2.6.39-rc4-00089-g2f666bc). 2.6.39-rc3 boots just fine.
>>>
>>> The backtrace [1] looks really messy.
>>>
>>> I have seen a similar backtrace at https://lkml.org/lkml/2011/3/25/169
>>> and tried the patch from https://lkml.org/lkml/2011/3/25/173 but it
>>> didn't help. The backtrace looks similar (much smaller) but the machine
>>> ends up dead as well with unbalanced preempt counter[2].
>>>
>>> The config is attached.
>>>
>>> Is this a known problem?
>>>
>>> ---
>>> * [1] backtrace with the current git tree (2f666bc)
>>>
>>> [ 31.207283] BUG: unable to handle kernel NULL pointer dereference at 0000000c
>>> NULL pointer dereference[ 31.207540] IP: at 0000000c
>>> [ 31.207540] IP: [<c028dece>] cfq_insert_request+0x1d/0x3f5
>>> [ 31.207720] *pde = 00000000 [<c028dece>] cfq_insert_request+0x1d/0x3f5
>>> NULL pointer dereference[ 31.207720] *pde = 00000000
>>> at 0000000c
>>> [ 31.207888] Oops: 0000 [#1]
>>> PREEMPT [ 31.207540] IP:[ 31.207888] Oops: 0000 [#1] SMP PREEMPT DEBUG_PAGEALLOC [<c028dece>] cfq_insert_request+0x1d/0x3f5
>>> SMP DEBUG_PAGEALLOC[ 31.207720] *pde = 00000000
>>> [ 31.207888] Oops: 0000 [#1] PREEMPT [ 31.208186] last sysfs file: /sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/queue/scheduler
>>
>> Ahh hang on, this may be a good clue. Does your boot scripts change the
>> IO scheduler?
>
> Good one...
> Yes, I have:
> echo deadline > /sys/block/sda/queue/scheduler
> in /etc/rc.local
>
> I am able to boot after I remove it. This is the first time I have seen
> "last sysfs file" being useful.
Haha, good point, it's the first time for me as well IO think.
> Still want me to test the patch from the other email?
No, that wont help you. I do wonder why this is a rc3 vs rc4 change.
I'll dig around and send you something to try.
--
Jens Axboe
next prev parent reply other threads:[~2011-04-20 13:31 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-20 12:58 2.6.39-rc4 BUG: unable to handle kernel NULL pointer dereference at 0000000c IP: cfq_insert_request+0x1d/0x3f5 Michal Hocko
2011-04-20 13:03 ` Jens Axboe
2011-04-20 13:13 ` Jens Axboe
2011-04-20 13:29 ` Michal Hocko
2011-04-20 13:31 ` Jens Axboe [this message]
2011-04-20 17:33 ` Jens Axboe
2011-04-21 7:16 ` Michal Hocko
2011-04-21 7:25 ` Jens Axboe
2011-04-21 14:38 ` Linus Torvalds
2011-04-21 15:29 ` Jens Axboe
2011-04-21 18:52 ` Michal Hocko
2011-04-21 18:51 ` Michal Hocko
2011-04-21 19:00 ` Jens Axboe
2011-04-22 7:00 ` Michal Hocko
2011-04-22 11:35 ` Jens Axboe
2011-04-22 20:30 ` Hugh Dickins
2011-04-21 15:04 ` Jeff Moyer
2011-04-21 15:27 ` Vivek Goyal
2011-04-21 15:51 ` Jeff Moyer
2011-04-21 15:30 ` Jens Axboe
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