Re: [BUG] mm/page-writeback.c: divide by zero in pos_ratio_polynom not fixed

[Steven Rostedt]

On Tue, 11 Nov 2014 21:15:39 +0100
Jan Kara <jack@xxxxxxx> wrote:


>   So I was looking into this but I have to say I don't understand where is
> the problem. The registers clearly show that x_intercept - bdi_setpoint + 1
> == 0 (in 32-bit arithmetics). Given:
>    x_intercept = bdi_setpoint + span
> 
> We have that span + 1 == 0 and that means that:
> ((thresh - bdi_thresh + 8 * write_bw) * (u64)x >> 16) == -1 (again in
> 32-bit arithmetics). But I don't see how that can realistically happen...
> 
> Is this reproducible at all?
> 

Unfortunately not. It only happened once, and I haven't been able to
reproduce it again.

-- Steve
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