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SubjectRe: linux-next: Tree for December 11
On Wed, Dec 17, 2008 at 00:08, Ingo Molnar <mingo@elte.hu> wrote:

>>
>> The warning can also be reproduced in qemu, so it was easy to bisect.
>>
>> commit 7317d7b87edb41a9135e30be1ec3f7ef817c53dd
>> Author: Nick Piggin <nickpiggin@yahoo.com.au>
>> Date: Tue Sep 30 20:50:27 2008 +1000
>>
>> sched: improve preempt debugging
>>
>> This patch helped me out with a problem I recently had....
>>
>> Basically, when the kernel lock is held, then preempt_count
>> underflow does not
>> get detected until it is released which may be a long time (and arbitrarily,
>> eg at different points it may be rescheduled). If the bkl is released at
>> schedule, the resulting output is actually fairly cryptic...
>>
>> With any other lock that elevates preempt_count, it is illegal to schedule
>> under it (which would get found pretty quickly). bkl allows scheduling with
>> preempt_count elevated, which makes underflows hard to debug.
>>
>> Signed-off-by: Ingo Molnar <mingo@elte.hu>
>>
>> I understand that not this particular commit is buggy, but at least
>> I've got someone to add to the CC. ;)
>>
>> Also the author's e-mail looks suspicious.
>
> Suspicious in what way?

Does not appear in signed-off-by.

>
> Ingo
>


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