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Commit bdc8cb98 authored by Dave Hansen's avatar Dave Hansen Committed by Linus Torvalds
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[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: default avatarDave Hansen <haveblue@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 208d54e5

include/linux/memory_hotplug.h

+37 −2
Original line number Diff line number Diff line
@@ -16,13 +16,36 @@ void pgdat_resize_lock(struct pglist_data *pgdat, unsigned long *flags) 
static inline

void pgdat_resize_unlock(struct pglist_data *pgdat, unsigned long *flags)

{

	spin_lock_irqrestore(&pgdat->node_size_lock, *flags);

	spin_unlock_irqrestore(&pgdat->node_size_lock, *flags);

}

static inline

void pgdat_resize_init(struct pglist_data *pgdat)

{

	spin_lock_init(&pgdat->node_size_lock);

}

/*

 * Zone resizing functions

 */

static inline unsigned zone_span_seqbegin(struct zone *zone)

{

	return read_seqbegin(&zone->span_seqlock);

}

static inline int zone_span_seqretry(struct zone *zone, unsigned iv)

{

	return read_seqretry(&zone->span_seqlock, iv);

}

static inline void zone_span_writelock(struct zone *zone)

{

	write_seqlock(&zone->span_seqlock);

}

static inline void zone_span_writeunlock(struct zone *zone)

{

	write_sequnlock(&zone->span_seqlock);

}

static inline void zone_seqlock_init(struct zone *zone)

{

	seqlock_init(&zone->span_seqlock);

}

#else /* ! CONFIG_MEMORY_HOTPLUG */

/*

 * Stub functions for when hotplug is off
@@ -30,5 +53,17 @@ void pgdat_resize_init(struct pglist_data *pgdat) 
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



static inline unsigned zone_span_seqbegin(struct zone *zone)

{

	return 0;

}

static inline int zone_span_seqretry(struct zone *zone, unsigned iv)

{

	return 0;

}

static inline void zone_span_writelock(struct zone *zone) {}

static inline void zone_span_writeunlock(struct zone *zone) {}

static inline void zone_seqlock_init(struct zone *zone) {}

#endif /* ! CONFIG_MEMORY_HOTPLUG */

#endif /* __LINUX_MEMORY_HOTPLUG_H */

include/linux/mmzone.h

+15 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/threads.h>

#include <linux/numa.h>

#include <linux/init.h>

#include <linux/seqlock.h>

#include <asm/atomic.h>



/* Free memory management - zoned buddy allocator.  */
@@ -137,6 +138,10 @@ struct zone { 
	 * free areas of different sizes

	 */

	spinlock_t		lock;

#ifdef CONFIG_MEMORY_HOTPLUG

	/* see spanned/present_pages for more description */

	seqlock_t		span_seqlock;

#endif

	struct free_area	free_area[MAX_ORDER];
@@ -220,6 +225,16 @@ struct zone { 
	/* zone_start_pfn == zone_start_paddr >> PAGE_SHIFT */

	unsigned long		zone_start_pfn;



	/*

	 * zone_start_pfn, spanned_pages and present_pages are all

	 * protected by span_seqlock.  It is a seqlock because it has

	 * to be read outside of zone->lock, and it is done in the main

	 * allocator path.  But, it is written quite infrequently.

	 *

	 * The lock is declared along with zone->lock because it is

	 * frequently read in proximity to zone->lock.  It's good to

	 * give them a chance of being in the same cacheline.

	 */

	unsigned long		spanned_pages;	/* total size, including holes */

	unsigned long		present_pages;	/* amount of memory (excluding holes) */

mm/page_alloc.c

+14 −5
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <linux/sysctl.h>

#include <linux/cpu.h>

#include <linux/cpuset.h>

#include <linux/memory_hotplug.h>

#include <linux/nodemask.h>

#include <linux/vmalloc.h>
@@ -80,12 +81,19 @@ unsigned long __initdata nr_all_pages; 


static int page_outside_zone_boundaries(struct zone *zone, struct page *page)

{

	if (page_to_pfn(page) >= zone->zone_start_pfn + zone->spanned_pages)

		return 1;

	if (page_to_pfn(page) < zone->zone_start_pfn)

		return 1;

	int ret = 0;

	unsigned seq;

	unsigned long pfn = page_to_pfn(page);



	return 0;

	do {

		seq = zone_span_seqbegin(zone);

		if (pfn >= zone->zone_start_pfn + zone->spanned_pages)

			ret = 1;

		else if (pfn < zone->zone_start_pfn)

			ret = 1;

	} while (zone_span_seqretry(zone, seq));



	return ret;

}



static int page_is_consistent(struct zone *zone, struct page *page)
@@ -1980,6 +1988,7 @@ static void __init free_area_init_core(struct pglist_data *pgdat, 
		zone->name = zone_names[j];

		spin_lock_init(&zone->lock);

		spin_lock_init(&zone->lru_lock);

		zone_seqlock_init(zone);

		zone->zone_pgdat = pgdat;

		zone->free_pages = 0;