On 2022/3/29 22:00, Christoph Hellwig wrote:
> On Tue, Mar 29, 2022 at 09:26:15PM +0800, Miaohe Lin wrote:
>> LRU_UNEVICTABLE is not taken into account when shrink lruvec. So we can
>> save a bit of stack space by shrinking the array size of nr and targets
>> to NR_LRU_LISTS - 1. No functional change intended.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>> ---
>> mm/vmscan.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index a6e60c78d058..ebd8ffb63673 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -2862,8 +2862,9 @@ static bool can_age_anon_pages(struct pglist_data *pgdat,
>>
>> static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
>> {
>> - unsigned long nr[NR_LRU_LISTS];
>> - unsigned long targets[NR_LRU_LISTS];
>> + /* LRU_UNEVICTABLE is not taken into account. */
>> + unsigned long nr[NR_LRU_LISTS - 1];
>> + unsigned long targets[NR_LRU_LISTS - 1];
>
> This looks like a problem waiting to happen..
IIUC, I am changing the array size to what it exactly uses now. And LRU_UNEVICTABLE won't be
used anyway. Could you please tell me what kind of problem is waiting to happen ? If this
will result in actual risk, I will drop this patch.
Thanks.
>
> .
>
