From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx194.postini.com [74.125.245.194]) by kanga.kvack.org (Postfix) with SMTP id A71AC6B0044 for ; Fri, 19 Oct 2012 03:42:08 -0400 (EDT) Received: by mail-ob0-f169.google.com with SMTP id va7so204605obc.14 for ; Fri, 19 Oct 2012 00:42:07 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1350629202-9664-9-git-send-email-wency@cn.fujitsu.com> References: <1350629202-9664-1-git-send-email-wency@cn.fujitsu.com> <1350629202-9664-9-git-send-email-wency@cn.fujitsu.com> From: KOSAKI Motohiro Date: Fri, 19 Oct 2012 03:41:47 -0400 Message-ID: Subject: Re: [PATCH v3 8/9] memory-hotplug: fix NR_FREE_PAGES mismatch Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: wency@cn.fujitsu.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, benh@kernel.crashing.org, paulus@samba.org, minchan.kim@gmail.com, akpm@linux-foundation.org, isimatu.yasuaki@jp.fujitsu.com, Christoph Lameter On Fri, Oct 19, 2012 at 2:46 AM, wrote: > From: Wen Congyang > > NR_FREE_PAGES will be wrong after offlining pages. We add/dec NR_FREE_PAGES > like this now: > 1. mova all pages in buddy system to MIGRATE_ISOLATE, and dec NR_FREE_PAGES move? > 2. don't add NR_FREE_PAGES when it is freed and the migratetype is MIGRATE_ISOLATE > 3. dec NR_FREE_PAGES when offlining isolated pages. > 4. add NR_FREE_PAGES when undoing isolate pages. > > When we come to step 3, all pages are in MIGRATE_ISOLATE list, and NR_FREE_PAGES > are right. When we come to step4, all pages are not in buddy system, so we don't > change NR_FREE_PAGES in this step, but we change NR_FREE_PAGES in step3. So > NR_FREE_PAGES is wrong after offlining pages. So there is no need to change > NR_FREE_PAGES in step3. Sorry, I don't understand this two paragraph. Can you please elaborate more? and one more trivial question: why do we need to call undo_isolate_page_range() from __offline_pages()? > > This patch also fixs a problem in step2: if the migratetype is MIGRATE_ISOLATE, > we should not add NR_FRR_PAGES when we remove pages from pcppages. Why drain_all_pages doesn't work? -- 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