On 06/18/2014 11:08 AM, Chen Yucong wrote:
> On Wed, 2014-06-18 at 11:00 +0200, Jerome Marchand wrote:
>>> if (!nr_file || !nr_anon)
>>> break;
>>>
>>> - if (nr_file > nr_anon) {
>>> - unsigned long scan_target =
>> targets[LRU_INACTIVE_ANON] +
>>>
>> - targets[LRU_ACTIVE_ANON]
>> + 1;
>>> + file_percent = nr_file * 100 / file_target;
>>> + anon_percent = nr_anon * 100 / anon_target;
>>
>> Here it could happen.
>>
>>
> The snippet
> ...
> if (!nr_file || !nr_anon)
> break;
Looks like nr[] values can only decrease and stay positive. Then the
following should be true at all times:
file_target >= nr_file >= 0
anon_target >= nr_anon >= 0
and the code above should indeed avoid the divide by zero.
Thanks,
Jerome
> ...
> can help us to filter the situation which you have described. It comes
> from Mel's patch that is called:
>
> mm: vmscan: use proportional scanning during direct reclaim and full
> scan at DEF_PRIORITY
>
> thx!
> cyc
>
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