On Mon, Mar 06, 2017 at 10:37:40AM +0900, Minchan Kim wrote: > On Fri, Mar 03, 2017 at 08:59:54AM +0100, Michal Hocko wrote: > > On Fri 03-03-17 10:26:09, Minchan Kim wrote: > > > On Tue, Feb 28, 2017 at 04:39:59PM -0500, Johannes Weiner wrote: > > > > @@ -3316,6 +3325,9 @@ static int balance_pgdat(pg_data_t *pgdat, int > > > > order, int classzone_idx) > > > > sc.priority--; > > > > } while (sc.priority >= 1); > > > > > > > > + if (!sc.nr_reclaimed) > > > > + pgdat->kswapd_failures++; > > > > > > sc.nr_reclaimed is reset to zero in above big loop's beginning so most of > > > time, > > > it pgdat->kswapd_failures is increased.
That wasn't intentional; I didn't see the sc.nr_reclaimed reset. --- >From e126db716926ff353b35f3a6205bd5853e01877b Mon Sep 17 00:00:00 2001 From: Johannes Weiner <[email protected]> Date: Mon, 6 Mar 2017 10:53:59 -0500 Subject: [PATCH] mm: fix 100% CPU kswapd busyloop on unreclaimable nodes fix Check kswapd failure against the cumulative nr_reclaimed count, not against the count from the lowest priority iteration. Suggested-by: Minchan Kim <[email protected]> Signed-off-by: Johannes Weiner <[email protected]> --- mm/vmscan.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index ddcff8a11c1e..b834b2dd4e19 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3179,9 +3179,9 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) count_vm_event(PAGEOUTRUN); do { + unsigned long nr_reclaimed = sc.nr_reclaimed; bool raise_priority = true; - sc.nr_reclaimed = 0; sc.reclaim_idx = classzone_idx; /* @@ -3271,7 +3271,8 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) * Raise priority if scanning rate is too low or there was no * progress in reclaiming pages */ - if (raise_priority || !sc.nr_reclaimed) + nr_reclaimed = sc.nr_reclaimed - nr_reclaimed; + if (raise_priority || !nr_reclaimed) sc.priority--; } while (sc.priority >= 1); -- 2.11.1
