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SubjectRe: A regression in recent 3.2 kernel: bdi_dirty_limit() divide error
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On Sat, 2012-01-07 at 22:56 +0800, Wu Fengguang wrote:
> Subject:
> Date: Sat Jan 07 22:50:45 CST 2012
>
> The uninitilized shift may lead to denominator=0 in
> prop_fraction_percpu() and divide error in bdi_dirty_limit().

I'm not seeing how, only proc_change_shift() can change ->index, and it
does that after it writes ->pg[index]->shift.

> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
> ---
> lib/proportions.c | 1 +
> 1 file changed, 1 insertion(+)
>
> --- linux.orig/lib/proportions.c 2012-01-07 22:50:29.000000000 +0800
> +++ linux/lib/proportions.c 2012-01-07 22:50:37.000000000 +0800
> @@ -82,6 +82,7 @@ int prop_descriptor_init(struct prop_des
>
> pd->index = 0;
> pd->pg[0].shift = shift;
> + pd->pg[1].shift = shift;
> mutex_init(&pd->mutex);
> err = percpu_counter_init(&pd->pg[0].events, 0);
> if (err)
>
>


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