On Tue 12-04-16 09:23:51, Vlastimil Babka wrote:
[...]
> It's a bit complicated, but I agree that something like this is needed to
> prevent unexpected endless loops. Alternatively you could maybe just extend
> compact_result to distinguish between COMPACT_SKIPPED (but possible after
> reclaim) and COMPACT_IMPOSSIBLE (or some better name?). Then
> compaction_withdrawn() would obviously be false for IMPOSSIBLE, while
> compaction_failed() would be true? Then you shouldn't need
> compaction_zonelist_suitable().
I would rather not add more states. My head spins with the current state
already...
> >+bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
> >+ int alloc_flags)
> >+{
> >+ struct zone *zone;
> >+ struct zoneref *z;
> >+
> >+ /*
> >+ * Make sure at least one zone would pass __compaction_suitable if we continue
> >+ * retrying the reclaim.
> >+ */
> >+ for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->classzone_idx,
>
> I think here you should s/classzone_idx/high_zoneidx/
true
>
> >+ ac->nodemask) {
> >+ unsigned long available;
> >+ enum compact_result compact_result;
> >+
> >+ /*
> >+ * Do not consider all the reclaimable memory because we do not
> >+ * want to trash just for a single high order allocation which
> >+ * is even not guaranteed to appear even if __compaction_suitable
> >+ * is happy about the watermark check.
> >+ */
> >+ available = zone_reclaimable_pages(zone) / order;
> >+ available += zone_page_state_snapshot(zone, NR_FREE_PAGES);
> >+ compact_result = __compaction_suitable(zone, order, alloc_flags,
> >+ ac->high_zoneidx, available);
>
> And vice versa here.
will fix this. Thanks!
--
Michal Hocko
SUSE Labs
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