From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 0A14860021B for ; Sat, 2 Jan 2010 05:46:57 -0500 (EST) Subject: Re: [PATCH] mm, lockdep: annotate reclaim context to zone reclaim too From: Peter Zijlstra In-Reply-To: <2f11576a1001012121o4f09d30n6dba925e74099da1@mail.gmail.com> References: <1262339141-4682-1-git-send-email-kosaki.motohiro@jp.fujitsu.com> <1262387986.16572.234.camel@laptop> <2f11576a1001012121o4f09d30n6dba925e74099da1@mail.gmail.com> Content-Type: text/plain; charset="UTF-8" Date: Sat, 02 Jan 2010 11:46:06 +0100 Message-ID: <1262429166.32223.32.camel@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: LKML , linux-mm , Andrew Morton , Nick Piggin , Ingo Molnar List-ID: On Sat, 2010-01-02 at 14:21 +0900, KOSAKI Motohiro wrote: > 2010/1/2 Peter Zijlstra : > > On Fri, 2010-01-01 at 18:45 +0900, KOSAKI Motohiro wrote: > >> Commit cf40bd16fd (lockdep: annotate reclaim context) introduced reclaim > >> context annotation. But it didn't annotate zone reclaim. This patch do it. > > > > And yet you didn't CC anyone involved in that patch, nor explain why you > > think it necessary, massive FAIL. > > > > The lockdep annotations cover all of kswapd() and direct reclaim through > > __alloc_pages_direct_reclaim(). So why would you need an explicit > > annotation in __zone_reclaim()? > > Thanks CCing. The point is zone-reclaim doesn't use > __alloc_pages_direct_reclaim. > current call graph is > > __alloc_pages_nodemask > get_page_from_freelist > zone_reclaim() > __alloc_pages_slowpath > __alloc_pages_direct_reclaim > try_to_free_pages > > Actually, if zone_reclaim_mode=1, VM never call > __alloc_pages_direct_reclaim in usual VM pressure. > Thus I think zone-reclaim should be annotated explicitly too. > I know almost user don't use zone reclaim mode. but explicit > annotation doesn't have any demerit, I think. Just be aware that the annotation isn't recursive, I'd have to trace all calls to __zone_reclaim, but if kswapd were ever to call it you'd just wrecked things by getting lockdep_clear_current_reclaim_state() called. So just make sure you don't shorten the existing notations by adding it here. Other than that it seems ok. -- 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