Hi Ming

On 09/11/2018 12:03 PM, Ming Lei wrote:

After the refcount is switched to atomic mode, the whole counting is
done on the atomic part. Then if the refcount need to switch to percpu mode
again, all percpu part of the counter is re-initialized as zero simply. This
is invariant with/without this patch.

Does the "whole counting" here means ?

(long)(sum (every cpu's refcounter)) + atomic refcounter

and when switch to atomic mode, there could be value left in atomic refcounter.
then the unsigned long percpu refcounter cound be decreased from 0.
	

From another angle, one request could be ended on a different cpu from the one where

it is issued.

Thanks
Jianchao