From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f181.google.com (mail-pd0-f181.google.com [209.85.192.181]) by kanga.kvack.org (Postfix) with ESMTP id 91E4B6B005A for ; Sat, 15 Feb 2014 23:00:55 -0500 (EST) Received: by mail-pd0-f181.google.com with SMTP id y10so13475962pdj.40 for ; Sat, 15 Feb 2014 20:00:55 -0800 (PST) Received: from mail-pb0-x236.google.com (mail-pb0-x236.google.com [2607:f8b0:400e:c01::236]) by mx.google.com with ESMTPS id vb2si10600796pbc.217.2014.02.15.20.00.53 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sat, 15 Feb 2014 20:00:54 -0800 (PST) Received: by mail-pb0-f54.google.com with SMTP id uo5so13890804pbc.41 for ; Sat, 15 Feb 2014 20:00:53 -0800 (PST) Date: Sat, 15 Feb 2014 20:00:03 -0800 (PST) From: Hugh Dickins Subject: Re: [RFC PATCH] mm/vmscan: remove two un-needed mem_cgroup_page_lruvec() call In-Reply-To: <000001cf2ac7$9abf23b0$d03d6b10$%yang@samsung.com> Message-ID: References: <000001cf2ac7$9abf23b0$d03d6b10$%yang@samsung.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Weijie Yang Cc: riel@redhat.com, Mel Gorman , Andrew Morton , Minchan Kim , weijie.yang.kh@gmail.com, linux-kernel , Linux-MM On Sun, 16 Feb 2014, Weijie Yang wrote: > In putback_inactive_pages() and move_active_pages_to_lru(), > lruvec is already an input parameter and pages are all from this lruvec, > therefore there is no need to call mem_cgroup_page_lruvec() in loop. > > Signed-off-by: Weijie Yang Looks plausible but I believe it's incorrect. The lruvec passed in is the one we took the pages from, but there's a small but real chance that the page has become uncharged meanwhile, and should now be put back on the root_mem_cgroup's lruvec instead of the original memcg's lruvec. Hugh > --- > mm/vmscan.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index a9c74b4..4804fdb 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1393,8 +1393,6 @@ putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list) > continue; > } > > - lruvec = mem_cgroup_page_lruvec(page, zone); > - > SetPageLRU(page); > lru = page_lru(page); > add_page_to_lru_list(page, lruvec, lru); > @@ -1602,7 +1600,6 @@ static void move_active_pages_to_lru(struct lruvec *lruvec, > > while (!list_empty(list)) { > page = lru_to_page(list); > - lruvec = mem_cgroup_page_lruvec(page, zone); > > VM_BUG_ON_PAGE(PageLRU(page), page); > SetPageLRU(page); > -- > 1.7.10.4 > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org