From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx107.postini.com [74.125.245.107]) by kanga.kvack.org (Postfix) with SMTP id 79FE46B0044 for ; Fri, 12 Oct 2012 15:28:44 -0400 (EDT) Received: by mail-ob0-f169.google.com with SMTP id va7so3884305obc.14 for ; Fri, 12 Oct 2012 12:28:43 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <506E46B6.3060502@jp.fujitsu.com> References: <506E43E0.70507@jp.fujitsu.com> <506E46B6.3060502@jp.fujitsu.com> From: KOSAKI Motohiro Date: Fri, 12 Oct 2012 15:28:23 -0400 Message-ID: Subject: Re: [PATCH 5/10] memory-hotplug : memory-hotplug: check page type in get_page_bootmem Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Yasuaki Ishimatsu Cc: x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, sparclinux@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, wency@cn.fujitsu.com On Thu, Oct 4, 2012 at 10:32 PM, Yasuaki Ishimatsu wrote: > The function get_page_bootmem() may be called more than one time to the same > page. There is no need to set page's type, private if the function is not > the first time called to the page. > > Note: the patch is just optimization and does not fix any problem. > > CC: David Rientjes > CC: Jiang Liu > CC: Len Brown > CC: Christoph Lameter > Cc: Minchan Kim > CC: Andrew Morton > CC: KOSAKI Motohiro > CC: Wen Congyang > Signed-off-by: Yasuaki Ishimatsu > --- > mm/memory_hotplug.c | 15 +++++++++++---- > 1 file changed, 11 insertions(+), 4 deletions(-) > > Index: linux-3.6/mm/memory_hotplug.c > =================================================================== > --- linux-3.6.orig/mm/memory_hotplug.c 2012-10-04 18:29:58.284676075 +0900 > +++ linux-3.6/mm/memory_hotplug.c 2012-10-04 18:30:03.454680542 +0900 > @@ -95,10 +95,17 @@ static void release_memory_resource(stru > static void get_page_bootmem(unsigned long info, struct page *page, > unsigned long type) > { > - page->lru.next = (struct list_head *) type; > - SetPagePrivate(page); > - set_page_private(page, info); > - atomic_inc(&page->_count); > + unsigned long page_type; > + > + page_type = (unsigned long)page->lru.next; If I understand correctly, page->lru.next might be uninitialized yet. Moreover, I have no seen any good effect in this patch. I don't understand why we need to increase code complexity. > + if (page_type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE || > + page_type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE){ > + page->lru.next = (struct list_head *)type; > + SetPagePrivate(page); > + set_page_private(page, info); > + atomic_inc(&page->_count); > + } else > + atomic_inc(&page->_count); > } > > /* reference to __meminit __free_pages_bootmem is valid > > -- > 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