From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx190.postini.com [74.125.245.190]) by kanga.kvack.org (Postfix) with SMTP id 32AEC6B0074 for ; Fri, 6 Jul 2012 05:16:03 -0400 (EDT) Message-ID: <4FF6ADD9.7040600@cn.fujitsu.com> Date: Fri, 06 Jul 2012 17:20:25 +0800 From: Wen Congyang MIME-Version: 1.0 Subject: Re: [RFC PATCH v2 4/13] memory-hotplug : remove /sys/firmware/memmap/X sysfs References: <4FF287C3.4030901@jp.fujitsu.com> <4FF28996.10702@jp.fujitsu.com> <4FF2929B.7030004@cn.fujitsu.com> <4FF3CA65.1020300@jp.fujitsu.com> <4FF3CFDC.50802@cn.fujitsu.com> <4FF3DA1E.9060505@jp.fujitsu.com> <4FF41484.3070806@cn.fujitsu.com> <4FF6A17C.6000808@jp.fujitsu.com> In-Reply-To: <4FF6A17C.6000808@jp.fujitsu.com> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-2022-JP Sender: owner-linux-mm@kvack.org List-ID: To: Yasuaki Ishimatsu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@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, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com At 07/06/2012 04:27 PM, Yasuaki Ishimatsu Wrote: > Hi Wen, > > 2012/07/04 19:01, Wen Congyang wrote: >> At 07/04/2012 01:52 PM, Yasuaki Ishimatsu Wrote: >>> Hi Wen, >>> >>> 2012/07/04 14:08, Wen Congyang wrote: >>>> At 07/04/2012 12:45 PM, Yasuaki Ishimatsu Wrote: >>>>> Hi Wen, >>>>> >>>>> 2012/07/03 15:35, Wen Congyang wrote: >>>>>> At 07/03/2012 01:56 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: David Rientjes >>>>>>> CC: Jiang Liu >>>>>>> CC: Len Brown >>>>>>> CC: Benjamin Herrenschmidt >>>>>>> CC: Paul Mackerras >>>>>>> CC: Christoph Lameter >>>>>>> Cc: Minchan Kim >>>>>>> CC: Andrew Morton >>>>>>> CC: KOSAKI Motohiro >>>>>>> Signed-off-by: Yasuaki Ishimatsu >>>>>>> >>>>>>> --- >>>>>>> drivers/firmware/memmap.c | 70 +++++++++++++++++++++++++++++++++++++++++++ >>>>>>> include/linux/firmware-map.h | 6 +++ >>>>>>> mm/memory_hotplug.c | 6 +++ >>>>>>> 3 files changed, 81 insertions(+), 1 deletion(-) >>>>>>> >>>>>>> Index: linux-3.5-rc4/mm/memory_hotplug.c >>>>>>> =================================================================== >>>>>>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c 2012-07-03 14:22:00.190240794 +0900 >>>>>>> +++ linux-3.5-rc4/mm/memory_hotplug.c 2012-07-03 14:22:03.549198802 +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 - 1, "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 2012-07-03 14:21:45.766421116 +0900 >>>>>>> +++ linux-3.5-rc4/include/linux/firmware-map.h 2012-07-03 14:22:03.550198789 +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 2012-07-03 14:21:45.761421180 +0900 >>>>>>> +++ linux-3.5-rc4/drivers/firmware/memmap.c 2012-07-03 14:22:03.569198549 +0900 >>>>>>> @@ -79,7 +79,16 @@ static const struct sysfs_ops memmap_att >>>>>>> .show = memmap_attr_show, >>>>>>> }; >>>>>>> >>>>>>> +static void release_firmware_map_entry(struct kobject *kobj) >>>>>>> +{ >>>>>>> + /* >>>>>>> + * FIXME : There is no idea. >>>>>>> + * How to free the entry which allocated bootmem? >>>>>>> + */ >>>>>> >>>>>> I find a function free_bootmem(), but I am not sure whether it can work here. >>>>> >>>>> It cannot work here. >>>>> >>>>>> Another problem: how to check whether the entry uses bootmem? >>>>> >>>>> When firmware_map_entry is allocated by kzalloc(), the page has PG_slab. >>>> >>>> This is not true. In my test, I find the page does not have PG_slab sometimes. >>> >>> I think that it depends on the allocated size. firmware_map_entry size is >>> smaller than PAGE_SIZE. So the page has PG_Slab. >> >> In my test, I add printk in the function firmware_map_add_hotplug() to display >> page's flags. And sometimes the page is not allocated by slab(I use PageSlab() >> to verify it). > > How did you check it? Could you send your debug patch? When the memory is not allocated from slab, the flags is 0x10000000008000.