Re: [PATCH 2/2] mm/madvise: skip MADV_PAGEOUT on shared swap cache pages

[Dave Hansen]

On 3/25/20 11:28 PM, Minchan Kim wrote:
>> diff -puN mm/madvise.c~madv-pageout-ignore-shared-swap-cache mm/madvise.c
>> --- a/mm/madvise.c~madv-pageout-ignore-shared-swap-cache	2020-03-23 16:30:52.022385888 -0700
>> +++ b/mm/madvise.c	2020-03-23 16:41:15.448384333 -0700
>> @@ -261,6 +261,7 @@ static struct page *pte_get_reclaim_page
>>  {
>>  	swp_entry_t entry;
>>  	struct page *page;
>> +	int nr_page_references = 0;
> nit: just 'referenced' would be enough.

I guess I could track one bit like that.  But, it would require checking
both page_mapcount() and page_swapcount() for being >1.  This way, I
just accumulate the count and have a check at a single place.

I think it ends up much simpler this way.