On Fri, Jun 03, 2011 at 12:54:39AM +0900, Hiroyuki Kamezawa wrote: > 2011/6/2 Johannes Weiner <hannes@xxxxxxxxxxx>: > > On Thu, Jun 02, 2011 at 10:16:59PM +0900, Hiroyuki Kamezawa wrote: > >> 2011/6/1 Johannes Weiner <hannes@xxxxxxxxxxx>: > >> > All lru list walkers have been converted to operate on per-memcg > >> > lists, the global per-zone lists are no longer required. > >> > > >> > This patch makes the per-memcg lists exclusive and removes the global > >> > lists from memcg-enabled kernels. > >> > > >> > The per-memcg lists now string up page descriptors directly, which > >> > unifies/simplifies the list isolation code of page reclaim as well as > >> > it saves a full double-linked list head for each page in the system. > >> > > >> > At the core of this change is the introduction of the lruvec > >> > structure, an array of all lru list heads. It exists for each zone > >> > globally, and for each zone per memcg. All lru list operations are > >> > now done in generic code against lruvecs, with the memcg lru list > >> > primitives only doing accounting and returning the proper lruvec for > >> > the currently scanned memcg on isolation, or for the respective page > >> > on putback. > >> > > >> > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> > >> > >> > >> could you divide this into > >> - introduce lruvec > >> - don't record section? information into pc->flags because we see > >> "page" on memcg LRU > >> and there is no requirement to get page from "pc". > >> - remove pc->lru completely > > > > Yes, that makes sense. It shall be fixed in the next version. > > > > BTW, IIUC, Transparent hugepage has a code to link a page to the > page->lru directly. [...] > But it may put a page onto wrong memcgs if we do link a page to > another page's page->lru > because 2 pages may be in different cgroup each other. Yes, I noticed that. If it splits a huge page, it does not just add the tailpages to the lru head, but it links them next to the head page. But I don't see how those pages could ever be in different memcgs? pages with page->mapping pointing to the same anon_vma are always in the same memcg, AFAIU. Only since broken COWs get their own, though. > > Could you check there are more codes which does link page->lru to nearby page's > page->lru ? Now, I'm not sure there are other codes....but we need care. I double check again. It's a tricky area, but I thought I covered all cases. Never hurts to reassure, though. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>