On Wed, Jul 20, 2016 at 04:21:47PM +0100, Mel Gorman wrote:
> Page reclaim determines whether a pgdat is unreclaimable by examining how
> many pages have been scanned since a page was freed and comparing that
> to the LRU sizes. Skipped pages are not considered reclaim candidates but
> contribute to scanned. This can prematurely mark a pgdat as unreclaimable
> and trigger an OOM kill.
>
> While this does not fix an OOM kill message reported by Joonsoo Kim,
> it did stop pgdat being marked unreclaimable.
>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> ---
> mm/vmscan.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 22aec2bcfeec..b16d578ce556 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1415,7 +1415,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
> LIST_HEAD(pages_skipped);
>
> for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan &&
> - !list_empty(src); scan++) {
> + !list_empty(src);) {
> struct page *page;
>
> page = lru_to_page(src);
> @@ -1429,6 +1429,9 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
> continue;
> }
>
> + /* Pages skipped do not contribute to scan */
> + scan++;
> +
As I mentioned in previous version, under irq-disabled-spin-lock, such
unbounded operation would make the latency spike worse if there are
lot of pages we should skip.
Don't we take care it?
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