From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id CCCE36B002D for ; Mon, 28 Nov 2011 02:03:36 -0500 (EST) Received: by lamb11 with SMTP id b11so661701lam.14 for ; Sun, 27 Nov 2011 23:03:32 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1322062951-1756-5-git-send-email-hannes@cmpxchg.org> References: <1322062951-1756-1-git-send-email-hannes@cmpxchg.org> <1322062951-1756-5-git-send-email-hannes@cmpxchg.org> Date: Mon, 28 Nov 2011 12:33:31 +0530 Message-ID: Subject: Re: [patch 4/8] mm: memcg: lookup_page_cgroup (almost) never returns NULL From: Balbir Singh Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Andrew Morton , KAMEZAWA Hiroyuki , Michal Hocko , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Wed, Nov 23, 2011 at 9:12 PM, Johannes Weiner wrote: > From: Johannes Weiner > > Pages have their corresponding page_cgroup descriptors set up before > they are used in userspace, and thus managed by a memory cgroup. > > The only time where lookup_page_cgroup() can return NULL is in the > page sanity checking code that executes while feeding pages into the > page allocator for the first time. > This is a legacy check from the days when we allocated PC during fault time on demand. It might make sense to assert on !pc in DEBUG_VM mode at some point in the future Balbir -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org