On Fri, May 20, 2011 at 12:01:12PM -0400, Andrew Lutomirski wrote:
> On Fri, May 20, 2011 at 11:33 AM, Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
>
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 8bfd450..a5c01e9 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -1430,7 +1430,10 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
> >
> > /* Check if we should syncronously wait for writeback */
> > if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
> > + unsigned long nr_active;
> > set_reclaim_mode(priority, sc, true);
> > + nr_active = clear_active_flags(&page_list, NULL);
> > + count_vm_events(PGDEACTIVATE, nr_active);
> > nr_reclaimed += shrink_page_list(&page_list, zone, sc);
> > }
> >
> > --
>
> I'm now running that patch *without* the pgdat_balanced fix or the
> need_resched check. The VM_BUG_ON doesn't happen but I still get
Please forget need_resched.
Instead of it, could you test shrink_slab patch with !pgdat_balanced?
@@ -231,8 +231,11 @@ unsigned long shrink_slab(struct shrink_control *shrink,
if (scanned == 0)
scanned = SWAP_CLUSTER_MAX;
- if (!down_read_trylock(&shrinker_rwsem))
- return 1; /* Assume we'll be able to shrink next time */
+ if (!down_read_trylock(&shrinker_rwsem)) {
+ /* Assume we'll be able to shrink next time */
+ ret = 1;
+ goto out;
+ }
list_for_each_entry(shrinker, &shrinker_list, list) {
unsigned long long delta;
@@ -286,6 +289,8 @@ unsigned long shrink_slab(struct shrink_control *shrink,
shrinker->nr += total_scan;
}
up_read(&shrinker_rwsem);
+out:
+ cond_resched();
return ret;
}
> incorrect OOM kills.
>
> However, if I replace the check with:
>
> if (false &&should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
>
> then my system lags under bad memory pressure but recovers without
> OOMs or oopses.
I agree you can see OOM but oops? Did you see any oops?
>
> Is that expected?
No.. :(
It's totally opposite.
That routine is for getting the memory althought we lose latency
It's another issue. :(
>
> --Andy
>
> > 1.7.1
> >
> > --
> > Kind regards,
> > Minchan Kim
> >
--
Kind regards,
Minchan Kim
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