Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755832Ab2F2DJ7 (ORCPT ); Thu, 28 Jun 2012 23:09:59 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:35032 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753521Ab2F2DJz (ORCPT ); Thu, 28 Jun 2012 23:09:55 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <4FED1C65.7010902@jp.fujitsu.com> Date: Fri, 29 Jun 2012 12:09:25 +0900 From: Yasuaki Ishimatsu User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Wen Congyang CC: , , , , , , , , , , Subject: Re: [RFC PATCH 4/12] memory-hotplug : remove /sys/firmware/memmap/X sysfs References: <4FEA9C88.1070800@jp.fujitsu.com> <4FEA9E5F.4070205@jp.fujitsu.com> <4FEBFA8D.5040607@cn.fujitsu.com> <4FEC10CB.3060403@jp.fujitsu.com> <4FEC17F8.1000405@cn.fujitsu.com> In-Reply-To: <4FEC17F8.1000405@cn.fujitsu.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8782 Lines: 281 Hi Wen, 2012/06/28 17:38, Wen Congyang wrote: > At 06/28/2012 04:07 PM, Yasuaki Ishimatsu Wrote: >> Hi Wen, >> >> 2012/06/28 15:32, Wen Congyang wrote: >>> At 06/27/2012 01:47 PM, Yasuaki Ishimatsu Wrote: >>>> When (hot)adding memory into system, /sys/firmware/memmap/X/{end, >>>> start, type} >>>> sysfs files are created. But there is no code to remove these files. >>>> The patch >>>> implements the function to remove them. >>>> >>>> Note : The code does not free firmware_map_entry since there is no >>>> way to free >>>> memory which is allocated by bootmem. >>>> >>>> CC: Len Brown >>>> CC: Benjamin Herrenschmidt >>>> CC: Paul Mackerras >>>> CC: Christoph Lameter >>>> Cc: Minchan Kim >>>> CC: Andrew Morton >>>> CC: KOSAKI Motohiro >>>> CC: Wen Congyang >>>> Signed-off-by: Yasuaki Ishimatsu >>>> >>>> --- >>>> drivers/firmware/memmap.c | 71 >>>> +++++++++++++++++++++++++++++++++++++++++++ >>>> include/linux/firmware-map.h | 6 +++ >>>> mm/memory_hotplug.c | 6 +++ >>>> 3 files changed, 82 insertions(+), 1 deletion(-) >>>> >>>> Index: linux-3.5-rc4/mm/memory_hotplug.c >>>> =================================================================== >>>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c 2012-06-26 >>>> 13:37:30.546288901 +0900 >>>> +++ linux-3.5-rc4/mm/memory_hotplug.c 2012-06-26 >>>> 13:44:37.069955820 +0900 >>>> @@ -661,7 +661,11 @@ EXPORT_SYMBOL_GPL(add_memory); >>>> >>>> int remove_memory(int nid, u64 start, u64 size) >>>> { >>>> - return -EBUSY; >>>> + lock_memory_hotplug(); >>>> + /* remove memmap entry */ >>>> + firmware_map_remove(start, start + size, "System RAM"); >>>> + unlock_memory_hotplug(); >>>> + return 0; >>>> >>>> } >>>> EXPORT_SYMBOL_GPL(remove_memory); >>>> Index: linux-3.5-rc4/include/linux/firmware-map.h >>>> =================================================================== >>>> --- linux-3.5-rc4.orig/include/linux/firmware-map.h 2012-06-25 >>>> 04:53:04.000000000 +0900 >>>> +++ linux-3.5-rc4/include/linux/firmware-map.h 2012-06-26 >>>> 13:44:37.070955807 +0900 >>>> @@ -25,6 +25,7 @@ >>>> >>>> int firmware_map_add_early(u64 start, u64 end, const char *type); >>>> int firmware_map_add_hotplug(u64 start, u64 end, const char *type); >>>> +int firmware_map_remove(u64 start, u64 end, const char *type); >>>> >>>> #else /* CONFIG_FIRMWARE_MEMMAP */ >>>> >>>> @@ -38,6 +39,11 @@ static inline int firmware_map_add_hotpl >>>> return 0; >>>> } >>>> >>>> +static inline int firmware_map_remove(u64 start, u64 end, const char >>>> *type) >>>> +{ >>>> + return 0; >>>> +} >>>> + >>>> #endif /* CONFIG_FIRMWARE_MEMMAP */ >>>> >>>> #endif /* _LINUX_FIRMWARE_MAP_H */ >>>> Index: linux-3.5-rc4/drivers/firmware/memmap.c >>>> =================================================================== >>>> --- linux-3.5-rc4.orig/drivers/firmware/memmap.c 2012-06-25 >>>> 04:53:04.000000000 +0900 >>>> +++ linux-3.5-rc4/drivers/firmware/memmap.c 2012-06-26 >>>> 13:47:17.606948898 +0900 >>>> @@ -123,6 +123,16 @@ static int firmware_map_add_entry(u64 st >>>> return 0; >>>> } >>>> >>>> +/** >>>> + * firmware_map_remove_entry() - Does the real work to remove a >>>> firmware >>>> + * memmap entry. >>>> + * @entry: removed entry. >>>> + **/ >>>> +static inline void firmware_map_remove_entry(struct >>>> firmware_map_entry *entry) >>>> +{ >>>> + list_del(&entry->list); >>>> +} >>>> + >>>> /* >>>> * Add memmap entry on sysfs >>>> */ >>>> @@ -144,6 +154,31 @@ static int add_sysfs_fw_map_entry(struct >>>> return 0; >>>> } >>>> >>>> +/* >>>> + * Remove memmap entry on sysfs >>>> + */ >>>> +static inline void remove_sysfs_fw_map_entry(struct >>>> firmware_map_entry *entry) >>>> +{ >>>> + kobject_del(&entry->kobj); >>>> +} >>>> + >>>> +/* >>>> + * Search memmap entry >>>> + */ >>>> + >>>> +struct firmware_map_entry * __meminit >>>> +find_firmware_map_entry(u64 start, u64 end, const char *type) >>>> +{ >>>> + struct firmware_map_entry *entry; >>>> + >>>> + list_for_each_entry(entry, &map_entries, list) >>>> + if ((entry->start == start) && (entry->end == end) && >>>> + (!strcmp(entry->type, type))) >>>> + return entry; >>>> + >>>> + return NULL; >>>> +} >>>> + >>>> /** >>>> * firmware_map_add_hotplug() - Adds a firmware mapping entry when >>>> we do >>>> * memory hotplug. >>>> @@ -196,6 +231,42 @@ int __init firmware_map_add_early(u64 st >>>> return firmware_map_add_entry(start, end, type, entry); >>>> } >>>> >>>> +void release_firmware_map_entry(struct firmware_map_entry *entry) >>>> +{ >>>> + /* >>>> + * FIXME : There is no idea. >>>> + * How to free the entry which allocated bootmem? >>>> + */ >>>> +} >>>> + >>>> +/** >>>> + * firmware_map_remove() - remove a firmware mapping entry >>>> + * @start: Start of the memory range. >>>> + * @end: End of the memory range (inclusive). >>>> + * @type: Type of the memory range. >>>> + * >>>> + * removes a firmware mapping entry. >>>> + * >>>> + * Returns 0 on success, or -EINVAL if no entry. >>>> + **/ >>>> +int __meminit firmware_map_remove(u64 start, u64 end, const char *type) >>>> +{ >>>> + struct firmware_map_entry *entry; >>>> + >>>> + entry = find_firmware_map_entry(start, end, type); >>> >>> Hmm, we cannot find the entry easily, because the end can be: >>> 1. start + size >>> 2. start + size - 1 >>> >>> So, We should fix this bug first. >> >> This is not a bug. >> >> start and size arguments of firmware_map_remove() include >> acpi_memory_info->{start_addr, length}. And when creating a >> firmware_map_entry, >> the entry is created by acpi_memory_info->{start_addr, length}. So I don't >> think that we need care your comment. > > If the memory device is hotpluged before the os starts, and the memory > map is included in e820 map, the entry will be created by firmware_map_add_early(). > > The function firmware_map_add_early() is called by e820_reserve_resources(): > ===================== > for (i = 0; i < e820_saved.nr_map; i++) { > struct e820entry *entry = &e820_saved.map[i]; > firmware_map_add_early(entry->addr, > entry->addr + entry->size - 1, > e820_type_to_string(entry->type)); > } > ===================== > > Note: the end is addr + size - 1, not addr + size. > > In such case, you cannot find the entry. Thank you for your explanation. I understood it. end argument of firmware_map_add_hotplug() has always "addr + size", not "addr + size - 1". I think that changing argument of firmware_map_add_early() is high risk since the function has been used since early times. So, I will unify to "addr + size - 1". Thanks, Yasuaki Ishimatsu > Thanks > Wen Congyang > >> >>> >>>> + if (!entry) >>>> + return -EINVAL; >>>> + >>>> + /* remove the memmap entry */ >>>> + remove_sysfs_fw_map_entry(entry); >>>> + >>>> + firmware_map_remove_entry(entry); >>>> + >>>> + release_firmware_map_entry(entry); >>> >>> I guess you want to free the memory in the above function. But I think >>> it is >>> not a good idea to free it here. We should free it when the >>> entry->kobj's kref >>> is decreased to 0. >> >> Thanks. >> I'll update your comment at next version. >> >> Thanks, >> Yasuaki Ishimatsu >> >>> >>> Thanks >>> Wen Congyang >>> >>>> + >>>> + return 0; >>>> +} >>>> + >>>> /* >>>> * Sysfs functions >>>> ------------------------------------------------------------- >>>> */ >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe >>>> linux-kernel" in >>>> the body of a message to majordomo@vger.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> Please read the FAQ at http://www.tux.org/lkml/ >>>> >>> >>> -- >>> 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 from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/