Johannes Weiner <hannes@xxxxxxxxxxx> writes: > On Tue, Mar 28, 2017 at 01:32:02PM +0800, Huang, Ying wrote: >> @@ -5908,16 +5907,19 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) >> css_put(&memcg->css); >> } >> >> -/* >> - * mem_cgroup_try_charge_swap - try charging a swap entry >> +/** >> + * mem_cgroup_try_charge_swap - try charging a set of swap entries >> * @page: page being added to swap >> - * @entry: swap entry to charge >> + * @entry: the first swap entry to charge >> + * @nr_entries: the number of swap entries to charge >> * >> - * Try to charge @entry to the memcg that @page belongs to. >> + * Try to charge @nr_entries swap entries starting from @entry to the >> + * memcg that @page belongs to. >> * >> * Returns 0 on success, -ENOMEM on failure. >> */ >> -int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) >> +int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry, >> + unsigned int nr_entries) > > I've pointed this out before, Yes. And I have replied to your original comments too :-) > but there doesn't seem to be a reason to > pass @nr_entries when we have the struct page. Why can't this function > just check PageTransHuge() by itself? Because sometimes we need to charge one swap entry for a THP. Please take a look at the original add_to_swap() implementation. For a THP, one swap entry will be allocated and charged to the mem cgroup before the THP is split. And I think it is not easy to change this, because we don't want to split THP if the mem cgroup for swap exceeds its limit. Best Regards, Huang, Ying -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
