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![David Rientjes](/assets/img/avatar_default.png)
There's a deadlock when concurrently hot-adding memory through the probe interface and switching a memory block from offline to online. When hot-adding memory via the probe interface, add_memory() first takes mem_hotplug_begin() and then device_lock() is later taken when registering the newly initialized memory block. This creates a lock dependency of (1) mem_hotplug.lock (2) dev->mutex. When switching a memory block from offline to online, dev->mutex is first grabbed in device_online() when the write(2) transitions an existing memory block from offline to online, and then online_pages() will take mem_hotplug_begin(). This creates a lock inversion between mem_hotplug.lock and dev->mutex. Vitaly reports that this deadlock can happen when kworker handling a probe event races with systemd-udevd switching a memory block's state. This patch requires the state transition to take mem_hotplug_begin() before dev->mutex. Hot-adding memory via the probe interface creates a memory block while holding mem_hotplug_begin(), there is no way to take dev->mutex first in this case. online_pages() and offline_pages() are only called when transitioning memory block state. We now require that mem_hotplug_begin() is taken before calling them -- this requires exporting the mem_hotplug_begin() and mem_hotplug_done() to generic code. In all hot-add and hot-remove cases, mem_hotplug_begin() is done prior to device_online(). This is all that is needed to avoid the deadlock. Signed-off-by: David Rientjes <rientjes@google.com> Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com> Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zhang Zhen <zhenzhang.zhang@huawei.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Wang Nan <wangnan0@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
279 lines
8.2 KiB
C
279 lines
8.2 KiB
C
#ifndef __LINUX_MEMORY_HOTPLUG_H
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#define __LINUX_MEMORY_HOTPLUG_H
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#include <linux/mmzone.h>
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#include <linux/spinlock.h>
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#include <linux/notifier.h>
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#include <linux/bug.h>
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struct page;
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struct zone;
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struct pglist_data;
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struct mem_section;
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struct memory_block;
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#ifdef CONFIG_MEMORY_HOTPLUG
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/*
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* Types for free bootmem stored in page->lru.next. These have to be in
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* some random range in unsigned long space for debugging purposes.
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*/
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enum {
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MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE = 12,
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SECTION_INFO = MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE,
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MIX_SECTION_INFO,
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NODE_INFO,
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MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE = NODE_INFO,
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};
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/* Types for control the zone type of onlined and offlined memory */
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enum {
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MMOP_OFFLINE = -1,
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MMOP_ONLINE_KEEP,
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MMOP_ONLINE_KERNEL,
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MMOP_ONLINE_MOVABLE,
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};
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/*
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* pgdat resizing functions
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*/
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static inline
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void pgdat_resize_lock(struct pglist_data *pgdat, unsigned long *flags)
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{
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spin_lock_irqsave(&pgdat->node_size_lock, *flags);
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}
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static inline
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void pgdat_resize_unlock(struct pglist_data *pgdat, unsigned long *flags)
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{
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spin_unlock_irqrestore(&pgdat->node_size_lock, *flags);
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}
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static inline
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void pgdat_resize_init(struct pglist_data *pgdat)
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{
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spin_lock_init(&pgdat->node_size_lock);
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}
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/*
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* Zone resizing functions
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*
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* Note: any attempt to resize a zone should has pgdat_resize_lock()
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* zone_span_writelock() both held. This ensure the size of a zone
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* can't be changed while pgdat_resize_lock() held.
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*/
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static inline unsigned zone_span_seqbegin(struct zone *zone)
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{
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return read_seqbegin(&zone->span_seqlock);
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}
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static inline int zone_span_seqretry(struct zone *zone, unsigned iv)
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{
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return read_seqretry(&zone->span_seqlock, iv);
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}
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static inline void zone_span_writelock(struct zone *zone)
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{
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write_seqlock(&zone->span_seqlock);
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}
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static inline void zone_span_writeunlock(struct zone *zone)
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{
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write_sequnlock(&zone->span_seqlock);
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}
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static inline void zone_seqlock_init(struct zone *zone)
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{
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seqlock_init(&zone->span_seqlock);
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}
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extern int zone_grow_free_lists(struct zone *zone, unsigned long new_nr_pages);
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extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
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extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
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/* VM interface that may be used by firmware interface */
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extern int online_pages(unsigned long, unsigned long, int);
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extern int test_pages_in_a_zone(unsigned long, unsigned long);
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extern void __offline_isolated_pages(unsigned long, unsigned long);
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typedef void (*online_page_callback_t)(struct page *page);
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extern int set_online_page_callback(online_page_callback_t callback);
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extern int restore_online_page_callback(online_page_callback_t callback);
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extern void __online_page_set_limits(struct page *page);
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extern void __online_page_increment_counters(struct page *page);
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extern void __online_page_free(struct page *page);
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extern int try_online_node(int nid);
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#ifdef CONFIG_MEMORY_HOTREMOVE
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extern bool is_pageblock_removable_nolock(struct page *page);
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extern int arch_remove_memory(u64 start, u64 size);
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extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
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unsigned long nr_pages);
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#endif /* CONFIG_MEMORY_HOTREMOVE */
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/* reasonably generic interface to expand the physical pages in a zone */
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extern int __add_pages(int nid, struct zone *zone, unsigned long start_pfn,
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unsigned long nr_pages);
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#ifdef CONFIG_NUMA
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extern int memory_add_physaddr_to_nid(u64 start);
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#else
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static inline int memory_add_physaddr_to_nid(u64 start)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_HAVE_ARCH_NODEDATA_EXTENSION
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/*
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* For supporting node-hotadd, we have to allocate a new pgdat.
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*
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* If an arch has generic style NODE_DATA(),
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* node_data[nid] = kzalloc() works well. But it depends on the architecture.
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*
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* In general, generic_alloc_nodedata() is used.
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* Now, arch_free_nodedata() is just defined for error path of node_hot_add.
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*
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*/
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extern pg_data_t *arch_alloc_nodedata(int nid);
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extern void arch_free_nodedata(pg_data_t *pgdat);
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extern void arch_refresh_nodedata(int nid, pg_data_t *pgdat);
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#else /* CONFIG_HAVE_ARCH_NODEDATA_EXTENSION */
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#define arch_alloc_nodedata(nid) generic_alloc_nodedata(nid)
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#define arch_free_nodedata(pgdat) generic_free_nodedata(pgdat)
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#ifdef CONFIG_NUMA
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/*
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* If ARCH_HAS_NODEDATA_EXTENSION=n, this func is used to allocate pgdat.
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* XXX: kmalloc_node() can't work well to get new node's memory at this time.
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* Because, pgdat for the new node is not allocated/initialized yet itself.
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* To use new node's memory, more consideration will be necessary.
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*/
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#define generic_alloc_nodedata(nid) \
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({ \
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kzalloc(sizeof(pg_data_t), GFP_KERNEL); \
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})
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/*
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* This definition is just for error path in node hotadd.
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* For node hotremove, we have to replace this.
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*/
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#define generic_free_nodedata(pgdat) kfree(pgdat)
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extern pg_data_t *node_data[];
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static inline void arch_refresh_nodedata(int nid, pg_data_t *pgdat)
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{
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node_data[nid] = pgdat;
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}
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#else /* !CONFIG_NUMA */
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/* never called */
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static inline pg_data_t *generic_alloc_nodedata(int nid)
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{
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BUG();
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return NULL;
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}
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static inline void generic_free_nodedata(pg_data_t *pgdat)
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{
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}
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static inline void arch_refresh_nodedata(int nid, pg_data_t *pgdat)
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{
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}
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#endif /* CONFIG_NUMA */
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#endif /* CONFIG_HAVE_ARCH_NODEDATA_EXTENSION */
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#ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE
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extern void register_page_bootmem_info_node(struct pglist_data *pgdat);
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#else
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static inline void register_page_bootmem_info_node(struct pglist_data *pgdat)
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{
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}
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#endif
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extern void put_page_bootmem(struct page *page);
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extern void get_page_bootmem(unsigned long ingo, struct page *page,
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unsigned long type);
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void get_online_mems(void);
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void put_online_mems(void);
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void mem_hotplug_begin(void);
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void mem_hotplug_done(void);
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#else /* ! CONFIG_MEMORY_HOTPLUG */
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/*
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* Stub functions for when hotplug is off
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*/
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static inline void pgdat_resize_lock(struct pglist_data *p, unsigned long *f) {}
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static inline void pgdat_resize_unlock(struct pglist_data *p, unsigned long *f) {}
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static inline void pgdat_resize_init(struct pglist_data *pgdat) {}
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static inline unsigned zone_span_seqbegin(struct zone *zone)
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{
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return 0;
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}
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static inline int zone_span_seqretry(struct zone *zone, unsigned iv)
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{
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return 0;
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}
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static inline void zone_span_writelock(struct zone *zone) {}
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static inline void zone_span_writeunlock(struct zone *zone) {}
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static inline void zone_seqlock_init(struct zone *zone) {}
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static inline int mhp_notimplemented(const char *func)
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{
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printk(KERN_WARNING "%s() called, with CONFIG_MEMORY_HOTPLUG disabled\n", func);
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dump_stack();
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return -ENOSYS;
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}
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static inline void register_page_bootmem_info_node(struct pglist_data *pgdat)
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{
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}
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static inline int try_online_node(int nid)
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{
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return 0;
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}
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static inline void get_online_mems(void) {}
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static inline void put_online_mems(void) {}
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static inline void mem_hotplug_begin(void) {}
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static inline void mem_hotplug_done(void) {}
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#endif /* ! CONFIG_MEMORY_HOTPLUG */
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#ifdef CONFIG_MEMORY_HOTREMOVE
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extern int is_mem_section_removable(unsigned long pfn, unsigned long nr_pages);
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extern void try_offline_node(int nid);
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extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
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extern void remove_memory(int nid, u64 start, u64 size);
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#else
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static inline int is_mem_section_removable(unsigned long pfn,
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unsigned long nr_pages)
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{
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return 0;
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}
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static inline void try_offline_node(int nid) {}
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static inline int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
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{
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return -EINVAL;
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}
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static inline void remove_memory(int nid, u64 start, u64 size) {}
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#endif /* CONFIG_MEMORY_HOTREMOVE */
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extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
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void *arg, int (*func)(struct memory_block *, void *));
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extern int add_memory(int nid, u64 start, u64 size);
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extern int zone_for_memory(int nid, u64 start, u64 size, int zone_default);
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extern int arch_add_memory(int nid, u64 start, u64 size);
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extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
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extern bool is_memblock_offlined(struct memory_block *mem);
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extern void remove_memory(int nid, u64 start, u64 size);
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extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn);
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extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms);
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extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
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unsigned long pnum);
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#endif /* __LINUX_MEMORY_HOTPLUG_H */
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