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 <[email protected]> > --- > 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?
