Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753891Ab1FBR5V (ORCPT ); Thu, 2 Jun 2011 13:57:21 -0400 Received: from zene.cmpxchg.org ([85.214.230.12]:41421 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753148Ab1FBR5U (ORCPT ); Thu, 2 Jun 2011 13:57:20 -0400 Date: Thu, 2 Jun 2011 19:57:02 +0200 From: Johannes Weiner To: Hiroyuki Kamezawa Cc: KAMEZAWA Hiroyuki , Daisuke Nishimura , Balbir Singh , Ying Han , Michal Hocko , Andrew Morton , Rik van Riel , Minchan Kim , KOSAKI Motohiro , Mel Gorman , Greg Thelen , Michel Lespinasse , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch 8/8] mm: make per-memcg lru lists exclusive Message-ID: <20110602175702.GI28684@cmpxchg.org> References: <1306909519-7286-1-git-send-email-hannes@cmpxchg.org> <1306909519-7286-9-git-send-email-hannes@cmpxchg.org> <20110602142408.GB28684@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2724 Lines: 64 On Fri, Jun 03, 2011 at 12:54:39AM +0900, Hiroyuki Kamezawa wrote: > 2011/6/2 Johannes Weiner : > > On Thu, Jun 02, 2011 at 10:16:59PM +0900, Hiroyuki Kamezawa wrote: > >> 2011/6/1 Johannes Weiner : > >> > 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 > >> > >> > >> 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/