Messages in this thread | | | Date | Tue, 3 Jun 2014 08:27:42 +0200 | From | Michal Hocko <> | Subject | Re: [patch v2] mm, memcg: periodically schedule when emptying page list |
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On Mon 02-06-14 17:51:25, David Rientjes wrote: > From: Hugh Dickins <hughd@google.com> > > mem_cgroup_force_empty_list() can iterate a large number of pages on an lru and > mem_cgroup_move_parent() doesn't return an errno unless certain criteria, none > of which indicate that the iteration may be taking too long, is met. > > We have encountered the following stack trace many times indicating > "need_resched set for > 51000020 ns (51 ticks) without schedule", for example: > > scheduler_tick() > <timer irq> > mem_cgroup_move_account+0x4d/0x1d5 > mem_cgroup_move_parent+0x8d/0x109 > mem_cgroup_reparent_charges+0x149/0x2ba > mem_cgroup_css_offline+0xeb/0x11b > cgroup_offline_fn+0x68/0x16b > process_one_work+0x129/0x350 > > If this iteration is taking too long, we still need to do cond_resched() even > when an individual page is not busy. > > [rientjes@google.com: changelog] > Signed-off-by: Hugh Dickins <hughd@google.com> > Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Thanks!
> --- > v2: always reschedule if needed, "page" itself may not have a pc mismatch > or been unable to isolate. > > mm/memcontrol.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4784,9 +4784,9 @@ static void mem_cgroup_force_empty_list(struct mem_cgroup *memcg, > if (mem_cgroup_move_parent(page, pc, memcg)) { > /* found lock contention or "pc" is obsolete. */ > busy = page; > - cond_resched(); > } else > busy = NULL; > + cond_resched(); > } while (!list_empty(list)); > } >
-- Michal Hocko SUSE Labs
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