On Tue, Aug 6, 2019 at 5:25 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > On Tue 06-08-19 17:15:05, Yafang Shao wrote: > > On Tue, Aug 6, 2019 at 5:05 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > [...] > > > > As you said, the direct reclaim path set it to 1, but the > > > > __node_reclaim() forgot to process may_shrink_slab. > > > > > > OK, I am blind obviously. Sorry about that. Anyway, why cannot we simply > > > get back to the original behavior by setting may_shrink_slab in that > > > path as well? > > > > You mean do it as the commit 0ff38490c836 did before ? > > I haven't check in which commit the shrink_slab() is removed from > > What I've had in mind was essentially this: > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7889f583ced9..8011288a80e2 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -4088,6 +4093,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in > .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP), > .may_swap = 1, > .reclaim_idx = gfp_zone(gfp_mask), > + .may_shrinkslab = 1; > }; > > trace_mm_vmscan_node_reclaim_begin(pgdat->node_id, order, > > shrink_node path already does shrink slab when the flag allows that. In > other words get us back to before 1c30844d2dfe because that has clearly > changed the long term node reclaim behavior just recently. > -- If we do it like this, then vm.min_slab_ratio will not take effect if there're enough relcaimable page cache. Seems there're bugs in the original behavior as well. Thanks Yafang
