Hi Wen, 2012/07/17 11:32, Wen Congyang wrote: > At 07/17/2012 09:54 AM, Yasuaki Ishimatsu Wrote: >> Hi Wen, >> >> 2012/07/17 10:44, Yasuaki Ishimatsu wrote: >>> Hi Wen, >>> >>> 2012/07/13 12:35, Wen Congyang wrote: >>>> At 07/09/2012 06:24 PM, Yasuaki Ishimatsu Wrote: >>>>> acpi_memory_device_remove() has been prepared to remove physical memory. >>>>> But, the function only frees acpi_memory_device currentlry. >>>>> >>>>> The patch adds following functions into acpi_memory_device_remove(): >>>>> - offline memory >>>>> - remove physical memory (only return -EBUSY) >>>>> - free acpi_memory_device >>>>> >>>>> CC: David Rientjes <rient...@google.com> >>>>> CC: Jiang Liu <liu...@gmail.com> >>>>> CC: Len Brown <len.br...@intel.com> >>>>> CC: Benjamin Herrenschmidt <b...@kernel.crashing.org> >>>>> CC: Paul Mackerras <pau...@samba.org> >>>>> CC: Christoph Lameter <c...@linux.com> >>>>> Cc: Minchan Kim <minchan....@gmail.com> >>>>> CC: Andrew Morton <a...@linux-foundation.org> >>>>> CC: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com> >>>>> CC: Wen Congyang <we...@cn.fujitsu.com> >>>>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com> >>>>> >>>>> --- >>>>> drivers/acpi/acpi_memhotplug.c | 26 +++++++++++++++++++++++++- >>>>> drivers/base/memory.c | 39 >>>>> +++++++++++++++++++++++++++++++++++++++ >>>>> include/linux/memory.h | 5 +++++ >>>>> include/linux/memory_hotplug.h | 1 + >>>>> mm/memory_hotplug.c | 8 ++++++++ >>>>> 5 files changed, 78 insertions(+), 1 deletion(-) >>>>> >>>>> Index: linux-3.5-rc6/drivers/acpi/acpi_memhotplug.c >>>>> =================================================================== >>>>> --- linux-3.5-rc6.orig/drivers/acpi/acpi_memhotplug.c 2012-07-09 >>>>> 18:08:29.946888653 +0900 >>>>> +++ linux-3.5-rc6/drivers/acpi/acpi_memhotplug.c 2012-07-09 >>>>> 18:08:43.470719531 +0900 >>>>> @@ -29,6 +29,7 @@ >>>>> #include <linux/module.h> >>>>> #include <linux/init.h> >>>>> #include <linux/types.h> >>>>> +#include <linux/memory.h> >>>>> #include <linux/memory_hotplug.h> >>>>> #include <linux/slab.h> >>>>> #include <acpi/acpi_drivers.h> >>>>> @@ -452,12 +453,35 @@ static int acpi_memory_device_add(struct >>>>> static int acpi_memory_device_remove(struct acpi_device *device, int >>>>> type) >>>>> { >>>>> struct acpi_memory_device *mem_device = NULL; >>>>> - >>>>> + struct acpi_memory_info *info, *tmp; >>>>> + int result; >>>>> + int node; >>>>> >>>>> if (!device || !acpi_driver_data(device)) >>>>> return -EINVAL; >>>>> >>>>> mem_device = acpi_driver_data(device); >>>>> + >>>>> + node = acpi_get_node(mem_device->device->handle); >>>>> + >>>>> + list_for_each_entry_safe(info, tmp, &mem_device->res_list, list) { >>>>> + if (!info->enabled) >>>>> + continue; >>>>> + >>>>> + if (!is_memblk_offline(info->start_addr, info->length)) { >>>>> + result = offline_memory(info->start_addr, info->length); >>>>> + if (result) >>>>> + return result; >>>>> + } >>>>> + >>>>> + result = remove_memory(node, info->start_addr, info->length); >>>> >>>> The user may online the memory between offline_memory() and >>>> remove_memory(). >>>> So I think we should lock memory hotplug before check the memory's status >>>> and release it after remove_memory(). >>> >>> How about get "mem_block->state_mutex" of removed memory? When offlining >>> memory, we need to change "memory_block->state" into "MEM_OFFLINE". >>> In this case, we get mem_block->state_mutex. So I think the mutex lock >>> is beneficial. >> >> It is not good idea since remove_memory frees mem_block structure... >> Do you have any ideas? > > Hmm, split offline_memory() to 2 functions: offline_pages() and > __offline_pages() > > offline_pages() > lock_memory_hotplug(); > __offline_pages(); > unlock_memory_hotplug(); > > and implement remove_memory() like this: > remove_memory() > lock_memory_hotplug() > if (!is_memblk_offline()) { > __offline_pages(); > } > // cleanup > unlock_memory_hotplug(); > > What about this?
I also thought about it once. But a problem remains. Current offilne_pages() cannot realize the memory has been removed by remove_memory(). So even if protecting the race by lock_memory_hotplug(), offline_pages() can offline the removed memory. offline_pages() should have the means to know the memory was removed. But I don't have good idea. Thanks, Yasuaki Ishimatsu > > Thanks > Wen Congyang >> >> Thanks, >> Yasuaki Ishimatsu >> >>> Thanks, >>> Yasuaki Ishimatsu >>> >>>> >>>> Thanks >>>> Wen Congyang >>>> >>>>> + if (result) >>>>> + return result; >>>>> + >>>>> + list_del(&info->list); >>>>> + kfree(info); >>>>> + } >>>>> + >>>>> kfree(mem_device); >>>>> >>>>> return 0; >>>>> Index: linux-3.5-rc6/include/linux/memory_hotplug.h >>>>> =================================================================== >>>>> --- linux-3.5-rc6.orig/include/linux/memory_hotplug.h 2012-07-09 >>>>> 18:08:29.955888542 +0900 >>>>> +++ linux-3.5-rc6/include/linux/memory_hotplug.h 2012-07-09 >>>>> 18:08:43.471719518 +0900 >>>>> @@ -233,6 +233,7 @@ static inline int is_mem_section_removab >>>>> extern int mem_online_node(int nid); >>>>> extern int add_memory(int nid, u64 start, u64 size); >>>>> extern int arch_add_memory(int nid, u64 start, u64 size); >>>>> +extern int remove_memory(int nid, u64 start, u64 size); >>>>> extern int offline_memory(u64 start, u64 size); >>>>> extern int sparse_add_one_section(struct zone *zone, unsigned long >>>>> start_pfn, >>>>> int >>>>> nr_pages); >>>>> Index: linux-3.5-rc6/mm/memory_hotplug.c >>>>> =================================================================== >>>>> --- linux-3.5-rc6.orig/mm/memory_hotplug.c 2012-07-09 >>>>> 18:08:29.953888567 +0900 >>>>> +++ linux-3.5-rc6/mm/memory_hotplug.c 2012-07-09 18:08:43.476719455 >>>>> +0900 >>>>> @@ -659,6 +659,14 @@ out: >>>>> } >>>>> EXPORT_SYMBOL_GPL(add_memory); >>>>> >>>>> +int remove_memory(int nid, u64 start, u64 size) >>>>> +{ >>>>> + return -EBUSY; >>>>> + >>>>> +} >>>>> +EXPORT_SYMBOL_GPL(remove_memory); >>>>> + >>>>> + >>>>> #ifdef CONFIG_MEMORY_HOTREMOVE >>>>> /* >>>>> * A free page on the buddy free lists (not the per-cpu lists) has >>>>> PageBuddy >>>>> Index: linux-3.5-rc6/drivers/base/memory.c >>>>> =================================================================== >>>>> --- linux-3.5-rc6.orig/drivers/base/memory.c 2012-07-09 >>>>> 18:08:29.947888640 +0900 >>>>> +++ linux-3.5-rc6/drivers/base/memory.c 2012-07-09 18:10:54.880076739 >>>>> +0900 >>>>> @@ -70,6 +70,45 @@ void unregister_memory_isolate_notifier( >>>>> } >>>>> EXPORT_SYMBOL(unregister_memory_isolate_notifier); >>>>> >>>>> +bool is_memblk_offline(unsigned long start, unsigned long size) >>>>> +{ >>>>> + struct memory_block *mem = NULL; >>>>> + struct mem_section *section; >>>>> + unsigned long start_pfn, end_pfn; >>>>> + unsigned long pfn, section_nr; >>>>> + >>>>> + start_pfn = PFN_DOWN(start); >>>>> + end_pfn = start_pfn + PFN_DOWN(start); >>>>> + >>>>> + for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { >>>>> + section_nr = pfn_to_section_nr(pfn); >>>>> + if (!present_section_nr(section_nr)); >>>>> + continue; >>>>> + >>>>> + section = __nr_to_section(section_nr); >>>>> + /* same memblock? */ >>>>> + if (mem) >>>>> + if((section_nr >= mem->start_section_nr) && >>>>> + (section_nr <= mem->end_section_nr)) >>>>> + continue; >>>>> + >>>>> + mem = find_memory_block_hinted(section, mem); >>>>> + if (!mem) >>>>> + continue; >>>>> + if (mem->state == MEM_OFFLINE) >>>>> + continue; >>>>> + >>>>> + kobject_put(&mem->dev.kobj); >>>>> + return false; >>>>> + } >>>>> + >>>>> + if (mem) >>>>> + kobject_put(&mem->dev.kobj); >>>>> + >>>>> + return true; >>>>> +} >>>>> +EXPORT_SYMBOL(is_memblk_offline); >>>>> + >>>>> /* >>>>> * register_memory - Setup a sysfs device for a memory block >>>>> */ >>>>> Index: linux-3.5-rc6/include/linux/memory.h >>>>> =================================================================== >>>>> --- linux-3.5-rc6.orig/include/linux/memory.h 2012-07-08 >>>>> 09:23:56.000000000 +0900 >>>>> +++ linux-3.5-rc6/include/linux/memory.h 2012-07-09 18:08:43.484719355 >>>>> +0900 >>>>> @@ -106,6 +106,10 @@ static inline int memory_isolate_notify( >>>>> { >>>>> return 0; >>>>> } >>>>> +static inline bool is_memblk_offline(unsigned long start, unsigned long >>>>> size) >>>>> +{ >>>>> + return false; >>>>> +} >>>>> #else >>>>> extern int register_memory_notifier(struct notifier_block *nb); >>>>> extern void unregister_memory_notifier(struct notifier_block *nb); >>>>> @@ -120,6 +124,7 @@ extern int memory_isolate_notify(unsigne >>>>> extern struct memory_block *find_memory_block_hinted(struct >>>>> mem_section *, >>>>> struct >>>>> memory_block *); >>>>> extern struct memory_block *find_memory_block(struct mem_section *); >>>>> +extern bool is_memblk_offline(unsigned long start, unsigned long size); >>>>> #define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<<PAGE_SHIFT) >>>>> enum mem_add_context { BOOT, HOTPLUG }; >>>>> #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ >>>>> >>>>> >>>> >>>> -- >>>> To unsubscribe, send a message with 'unsubscribe linux-mm' in >>>> the body to majord...@kvack.org. For more info on Linux MM, >>>> see: http://www.linux-mm.org/ . >>>> Don't email: <a href=mailto:"d...@kvack.org"> em...@kvack.org </a> >>>> >>> >>> >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in >>> the body of a message to majord...@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >> >> >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in >> the body of a message to majord...@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/