(2012/08/11 0:42), Michal Hocko wrote:
On Thu 09-08-12 17:01:10, Glauber Costa wrote: [...]@@ -2317,18 +2318,18 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, } else mem_over_limit = mem_cgroup_from_res_counter(fail_res, res); /* - * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch - * of regular pages (CHARGE_BATCH), or a single regular page (1). - * * Never reclaim on behalf of optional batching, retry with a * single page instead. */ - if (nr_pages == CHARGE_BATCH) + if (nr_pages > min_pages) return CHARGE_RETRY;This is dangerous because THP charges will be retried now while they previously failed with CHARGE_NOMEM which means that we will keep attempting potentially endlessly.
with THP, I thought nr_pages == min_pages, and no retry.
Why cannot we simply do if (nr_pages < CHARGE_BATCH) and get rid of the min_pages altogether?
Hm, I think a slab can be larger than CHARGE_BATCH.
Also the comment doesn't seem to be valid anymore.
I agree it's not clean. Because our assumption on nr_pages are changed, I think this behavior should not depend on nr_pages value.. Shouldn't we have a flag to indicate "trial-for-batched charge" ? Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
