From 208d54e5513c0c02d85af0990901354c74364d5c Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Sat, 29 Oct 2005 18:16:52 -0700 Subject: [PATCH] memory hotplug locking: node_size_lock pgdat->node_size_lock is basically only neeeded in one place in the normal code: show_mem(), which is the arch-specific sysrq-m printing function. Strictly speaking, the architectures not doing memory hotplug do no need this locking in show_mem(). However, they are all included for completeness. This should also make any future consolidation of all of the implementations a little more straightforward. This lock is also held in the sparsemem code during a memory removal, as sections are invalidated. This is the place there pfn_valid() is made false for a memory area that's being removed. The lock is only required when doing pfn_valid() operations on memory which the user does not already have a reference on the page, such as in show_mem(). Signed-off-by: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memory_hotplug.h | 34 ++++++++++++++++++++++++++++++++++ include/linux/mmzone.h | 12 ++++++++++++ 2 files changed, 46 insertions(+) create mode 100644 include/linux/memory_hotplug.h (limited to 'include/linux') diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h new file mode 100644 index 000000000000..e8103be9d528 --- /dev/null +++ b/include/linux/memory_hotplug.h @@ -0,0 +1,34 @@ +#ifndef __LINUX_MEMORY_HOTPLUG_H +#define __LINUX_MEMORY_HOTPLUG_H + +#include +#include + +#ifdef CONFIG_MEMORY_HOTPLUG +/* + * pgdat resizing functions + */ +static inline +void pgdat_resize_lock(struct pglist_data *pgdat, unsigned long *flags) +{ + spin_lock_irqsave(&pgdat->node_size_lock, *flags); +} +static inline +void pgdat_resize_unlock(struct pglist_data *pgdat, unsigned long *flags) +{ + spin_lock_irqrestore(&pgdat->node_size_lock, *flags); +} +static inline +void pgdat_resize_init(struct pglist_data *pgdat) +{ + spin_lock_init(&pgdat->node_size_lock); +} +#else /* ! CONFIG_MEMORY_HOTPLUG */ +/* + * Stub functions for when hotplug is off + */ +static inline void pgdat_resize_lock(struct pglist_data *p, unsigned long *f) {} +static inline void pgdat_resize_unlock(struct pglist_data *p, unsigned long *f) {} +static inline void pgdat_resize_init(struct pglist_data *pgdat) {} +#endif +#endif /* __LINUX_MEMORY_HOTPLUG_H */ diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 4674145bb63d..e050d68963a1 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -273,6 +273,16 @@ typedef struct pglist_data { struct page *node_mem_map; #endif struct bootmem_data *bdata; +#ifdef CONFIG_MEMORY_HOTPLUG + /* + * Must be held any time you expect node_start_pfn, node_present_pages + * or node_spanned_pages stay constant. Holding this will also + * guarantee that any pfn_valid() stays that way. + * + * Nests above zone->lock and zone->size_seqlock. + */ + spinlock_t node_size_lock; +#endif unsigned long node_start_pfn; unsigned long node_present_pages; /* total number of physical pages */ unsigned long node_spanned_pages; /* total size of physical page @@ -293,6 +303,8 @@ typedef struct pglist_data { #endif #define nid_page_nr(nid, pagenr) pgdat_page_nr(NODE_DATA(nid),(pagenr)) +#include + extern struct pglist_data *pgdat_list; void __get_zone_counts(unsigned long *active, unsigned long *inactive, -- cgit v1.2.3