[PATCH] memory hotplug locking: zone span seqlock
See the "fixup bad_range()" patch for more information, but this actually creates a the lock to protect things making assumptions about a zone's size staying constant at runtime. Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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208d54e551
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3 changed files with 66 additions and 7 deletions
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@ -16,13 +16,36 @@ void pgdat_resize_lock(struct pglist_data *pgdat, unsigned long *flags)
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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_lock_irqrestore(&pgdat->node_size_lock, *flags);
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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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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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#else /* ! CONFIG_MEMORY_HOTPLUG */
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/*
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* Stub functions for when hotplug is off
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@ -30,5 +53,17 @@ void pgdat_resize_init(struct pglist_data *pgdat)
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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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#endif
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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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#endif /* ! CONFIG_MEMORY_HOTPLUG */
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#endif /* __LINUX_MEMORY_HOTPLUG_H */
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@ -12,6 +12,7 @@
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#include <linux/threads.h>
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#include <linux/numa.h>
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#include <linux/init.h>
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#include <linux/seqlock.h>
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#include <asm/atomic.h>
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/* Free memory management - zoned buddy allocator. */
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@ -137,6 +138,10 @@ struct zone {
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* free areas of different sizes
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*/
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spinlock_t lock;
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#ifdef CONFIG_MEMORY_HOTPLUG
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/* see spanned/present_pages for more description */
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seqlock_t span_seqlock;
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#endif
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struct free_area free_area[MAX_ORDER];
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@ -220,6 +225,16 @@ struct zone {
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/* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */
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unsigned long zone_start_pfn;
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/*
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* zone_start_pfn, spanned_pages and present_pages are all
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* protected by span_seqlock. It is a seqlock because it has
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* to be read outside of zone->lock, and it is done in the main
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* allocator path. But, it is written quite infrequently.
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*
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* The lock is declared along with zone->lock because it is
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* frequently read in proximity to zone->lock. It's good to
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* give them a chance of being in the same cacheline.
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*/
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unsigned long spanned_pages; /* total size, including holes */
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unsigned long present_pages; /* amount of memory (excluding holes) */
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@ -33,6 +33,7 @@
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#include <linux/sysctl.h>
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#include <linux/cpu.h>
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#include <linux/cpuset.h>
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#include <linux/memory_hotplug.h>
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#include <linux/nodemask.h>
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#include <linux/vmalloc.h>
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@ -80,12 +81,19 @@ unsigned long __initdata nr_all_pages;
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static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
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{
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if (page_to_pfn(page) >= zone->zone_start_pfn + zone->spanned_pages)
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return 1;
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if (page_to_pfn(page) < zone->zone_start_pfn)
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return 1;
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int ret = 0;
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unsigned seq;
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unsigned long pfn = page_to_pfn(page);
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return 0;
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do {
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seq = zone_span_seqbegin(zone);
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if (pfn >= zone->zone_start_pfn + zone->spanned_pages)
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ret = 1;
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else if (pfn < zone->zone_start_pfn)
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ret = 1;
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} while (zone_span_seqretry(zone, seq));
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return ret;
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}
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static int page_is_consistent(struct zone *zone, struct page *page)
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@ -1980,6 +1988,7 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
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zone->name = zone_names[j];
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spin_lock_init(&zone->lock);
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spin_lock_init(&zone->lru_lock);
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zone_seqlock_init(zone);
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zone->zone_pgdat = pgdat;
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zone->free_pages = 0;
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