From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wen Congyang Subject: Re: [RFC v8 PATCH 13/20] memory-hotplug: check page type in get_page_bootmem Date: Tue, 04 Sep 2012 11:46:11 +0800 Message-ID: <50457983.1050304@cn.fujitsu.com> References: <1346148027-24468-1-git-send-email-wency@cn.fujitsu.com> <1346148027-24468-14-git-send-email-wency@cn.fujitsu.com> <20120831143032.1343e99a.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from cn.fujitsu.com ([222.73.24.84]:44118 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756633Ab2IDDon (ORCPT ); Mon, 3 Sep 2012 23:44:43 -0400 In-Reply-To: <20120831143032.1343e99a.akpm@linux-foundation.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Andrew Morton , isimatu.yasuaki@jp.fujitsu.com 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, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, kosaki.motohiro@jp.fujitsu.com Hi, isimatu-san At 09/01/2012 05:30 AM, Andrew Morton Wrote: > On Tue, 28 Aug 2012 18:00:20 +0800 > wency@cn.fujitsu.com wrote: > >> From: Yasuaki Ishimatsu >> >> There is a possibility that get_page_bootmem() is called to the same page many >> times. So when get_page_bootmem is called to the same page, the function only >> increments page->_count. > > I really don't understand this explanation, even after having looked at > the code. Can you please have another attempt at the changelog? What is the problem that you want to fix? The function get_page_bootmem() may be called to the same page more than once, but I don't find any problem about current implementation. Thanks Wen Congyang > >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -95,10 +95,17 @@ static void release_memory_resource(struct resource *res) >> 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 (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); >> } > > And a code comment which explains what is going on would be good. As > is always the case ;) > > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wen Congyang Date: Tue, 04 Sep 2012 03:46:11 +0000 Subject: Re: [RFC v8 PATCH 13/20] memory-hotplug: check page type in get_page_bootmem Message-Id: <50457983.1050304@cn.fujitsu.com> List-Id: References: <1346148027-24468-1-git-send-email-wency@cn.fujitsu.com> <1346148027-24468-14-git-send-email-wency@cn.fujitsu.com> <20120831143032.1343e99a.akpm@linux-foundation.org> In-Reply-To: <20120831143032.1343e99a.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrew Morton , isimatu.yasuaki@jp.fujitsu.com 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, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, kosaki.motohiro@jp.fujitsu.com Hi, isimatu-san At 09/01/2012 05:30 AM, Andrew Morton Wrote: > On Tue, 28 Aug 2012 18:00:20 +0800 > wency@cn.fujitsu.com wrote: > >> From: Yasuaki Ishimatsu >> >> There is a possibility that get_page_bootmem() is called to the same page many >> times. So when get_page_bootmem is called to the same page, the function only >> increments page->_count. > > I really don't understand this explanation, even after having looked at > the code. Can you please have another attempt at the changelog? What is the problem that you want to fix? The function get_page_bootmem() may be called to the same page more than once, but I don't find any problem about current implementation. Thanks Wen Congyang > >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -95,10 +95,17 @@ static void release_memory_resource(struct resource *res) >> 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 (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); >> } > > And a code comment which explains what is going on would be good. As > is always the case ;) > > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from song.cn.fujitsu.com (unknown [222.73.24.84]) by ozlabs.org (Postfix) with ESMTP id 431EA2C008B for ; Tue, 4 Sep 2012 13:44:44 +1000 (EST) Message-ID: <50457983.1050304@cn.fujitsu.com> Date: Tue, 04 Sep 2012 11:46:11 +0800 From: Wen Congyang MIME-Version: 1.0 To: Andrew Morton , isimatu.yasuaki@jp.fujitsu.com Subject: Re: [RFC v8 PATCH 13/20] memory-hotplug: check page type in get_page_bootmem References: <1346148027-24468-1-git-send-email-wency@cn.fujitsu.com> <1346148027-24468-14-git-send-email-wency@cn.fujitsu.com> <20120831143032.1343e99a.akpm@linux-foundation.org> In-Reply-To: <20120831143032.1343e99a.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1 Cc: linux-s390@vger.kernel.org, linux-ia64@vger.kernel.org, len.brown@intel.com, linux-acpi@vger.kernel.org, linux-sh@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, cmetcalf@tilera.com, linux-mm@kvack.org, paulus@samba.org, minchan.kim@gmail.com, kosaki.motohiro@jp.fujitsu.com, rientjes@google.com, sparclinux@vger.kernel.org, cl@linux.com, linuxppc-dev@lists.ozlabs.org, liuj97@gmail.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, isimatu-san At 09/01/2012 05:30 AM, Andrew Morton Wrote: > On Tue, 28 Aug 2012 18:00:20 +0800 > wency@cn.fujitsu.com wrote: > >> From: Yasuaki Ishimatsu >> >> There is a possibility that get_page_bootmem() is called to the same page many >> times. So when get_page_bootmem is called to the same page, the function only >> increments page->_count. > > I really don't understand this explanation, even after having looked at > the code. Can you please have another attempt at the changelog? What is the problem that you want to fix? The function get_page_bootmem() may be called to the same page more than once, but I don't find any problem about current implementation. Thanks Wen Congyang > >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -95,10 +95,17 @@ static void release_memory_resource(struct resource *res) >> 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 (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); >> } > > And a code comment which explains what is going on would be good. As > is always the case ;) > > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx165.postini.com [74.125.245.165]) by kanga.kvack.org (Postfix) with SMTP id E3CCE6B005D for ; Mon, 3 Sep 2012 23:44:47 -0400 (EDT) Message-ID: <50457983.1050304@cn.fujitsu.com> Date: Tue, 04 Sep 2012 11:46:11 +0800 From: Wen Congyang MIME-Version: 1.0 Subject: Re: [RFC v8 PATCH 13/20] memory-hotplug: check page type in get_page_bootmem References: <1346148027-24468-1-git-send-email-wency@cn.fujitsu.com> <1346148027-24468-14-git-send-email-wency@cn.fujitsu.com> <20120831143032.1343e99a.akpm@linux-foundation.org> In-Reply-To: <20120831143032.1343e99a.akpm@linux-foundation.org> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , isimatu.yasuaki@jp.fujitsu.com 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, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, kosaki.motohiro@jp.fujitsu.com Hi, isimatu-san At 09/01/2012 05:30 AM, Andrew Morton Wrote: > On Tue, 28 Aug 2012 18:00:20 +0800 > wency@cn.fujitsu.com wrote: > >> From: Yasuaki Ishimatsu >> >> There is a possibility that get_page_bootmem() is called to the same page many >> times. So when get_page_bootmem is called to the same page, the function only >> increments page->_count. > > I really don't understand this explanation, even after having looked at > the code. Can you please have another attempt at the changelog? What is the problem that you want to fix? The function get_page_bootmem() may be called to the same page more than once, but I don't find any problem about current implementation. Thanks Wen Congyang > >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -95,10 +95,17 @@ static void release_memory_resource(struct resource *res) >> 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 (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); >> } > > And a code comment which explains what is going on would be good. As > is always the case ;) > > -- 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