BUG: scheduling while atomic

[Dave Hylands]

Hi Arun,

On Wed, Apr 18, 2012 at 1:58 AM, Arun KS <getarunks at gmail.com> wrote:
>
>
> On Wed, Apr 18, 2012 at 12:14 PM, Arun KS <getarunks at gmail.com> wrote:
>>
>>
>> Hello Guys,
>>
>> System is working normal after this BUG.
>> PC is at 0x400b4614, probably a mmaped address.
>>
>> Just wondering how can this BUG happen when a process is running in user
>> space.
>>
>>
>> Can it be something like this
>> 1) enter to kernel from userspace through some system call.
>> 2) kernel disables the interrupt and return to user space.
>> 3) and now it can happen in user space?
>>
>> Any thoughts?
>>
>> shell at android: # ls
>> device[   40.603515] BUG: scheduling while atomic: Binder Thread
>> #/1355/0x00010003
>> [   40.610290] Modules linked in:
>> [   40.613342]
>> [   40.614837] Pid: 1355, comm:      Binder Thread #
>> [   40.619506] CPU: 0    Tainted: G        W    (3.0.15+ #174)
>> [   40.625061] PC is at 0x400b4614
>> [   40.628173] LR is at 0x408d83c9
>> [   40.631317] pc : [<400b4614>]    lr : [<408d83c9>]    psr: 40000010
>> [   40.631317] sp : 50551918  ip : 4092d1c0  fp : 505519a4
>> [   40.642730] r10: 50551974  r9 : 5016de28  r8 : 1f600009
>> [   40.647949] r7 : 00000000  r6 : 00000000  r5 : 5055194c  r4 : 00f09f90
>> [   40.654418] r3 : 40931c58  r2 : 00000000  r1 : 00f09f90  r0 : 00000006
>> [   40.660919] Flags: nZcv  IRQs on  FIQs on  Mode USER_32  ISA ARM
>> Segment user
>
>
> But if you look at the flags here,  it is showing that IRQs are on.
>
>> [   40.668121] Control: 10c53c7d  Table: 91184059  DAC: 00000015

So, an atomic context, as far as the kernel is concerned, also
includes disabling preemption, not just disabling interrupts.

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com