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SubjectRe: [patch] as-iosched divide by zero fix


Robert Love wrote:

>On Wed, 2003-06-11 at 17:24, Andrew Morton wrote:
>
>
>>Do you know what the actual oops is?
>>
>
>I got it all figured out now.
>
>It is a divide by zero in update_write_batch() called from
>as_completed_request().
>
>
>>Odd that starting the X server triggers it. Be interesting if your patch
>>fixes things for Brian.
>>
>
>I reproduced it without X.
>
>The divide by zero is on line 959 with the divide by 'write_time'. It
>can obviously be zero (see line 950). The divide by 'batch' on line 953
>seems safe.
>
>The correct patch is below.
>

Probably put in the other check to be on the safe side.
And can the check be if (!write_time || (batch / write_time > 2)
>
>
>Most important question: why are only some of us seeing this?
>

It would occur if a write batch didn't take any jiffies, which
isn't very likely. The HZ=100 change probbly brought it out.
Thanks guys.


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