> On Feb 7, 2016, at 1:41 PM, Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> wrote: > >> On Thu, Feb 04, 2016 at 03:07:47PM -0500, Johannes Weiner wrote: >> Migration accounting in the memory controller used to have to handle >> both oldpage and newpage being on the LRU already; fuse's page cache >> replacement used to pass a recycled newpage that had been uncharged >> but not freed and removed from the LRU, and the memcg migration code >> used to uncharge oldpage to "pass on" the existing charge to newpage. >> >> Nowadays, pages are no longer uncharged when truncated from the page >> cache, but rather only at free time, so if a LRU page is recycled in >> page cache replacement it'll also still be charged. And we bail out of >> the charge transfer altogether in that case. Tell commit_charge() that >> we know newpage is not on the LRU, to avoid taking the zone->lru_lock >> unnecessarily from the migration path. >> >> But also, oldpage is no longer uncharged inside migration. We only use >> oldpage for its page->mem_cgroup and page size, so we don't care about >> its LRU state anymore either. Remove any mention from the kernel doc. >> >> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> >> Suggested-by: Hugh Dickins <hughd@xxxxxxxxxx> > > Acked-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Thanks! > @@ -5483,6 +5483,7 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage) > unsigned int nr_pages; > bool compound; > > + VM_BUG_ON_PAGE(PageLRU(newpage), newpage); That's actually possible for fuse. But in that case newpage is charged and we bail. -- 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