Messages in this thread | | | Date | Wed, 20 Apr 2011 15:13:15 +0200 | From | Jens Axboe <> | Subject | Re: 2.6.39-rc4 BUG: unable to handle kernel NULL pointer dereference at 0000000c IP: cfq_insert_request+0x1d/0x3f5 |
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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?
-- Jens Axboe
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