This patch adds locking functions that are used for restricting
addition and removal of zones while looking up zones by for_each_zone
etc. This feature is required for pzones because zones are added and
removed dynamically in pzones.
for_each_zone and its family should be surrounded by
read_lock_nr_zones and read_unlock_nr_zones. The code that adds or
removes zones should call write_lock_nr_zones and write_unlock_nr_zones.
Signed-off-by: KUROSAWA Takahiro <[EMAIL PROTECTED]>
---
include/linux/mmzone.h | 4 ++
mm/page_alloc.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++
mm/vmscan.c | 2 +
3 files changed, 74 insertions(+)
diff -urNp linux-2.6.15/include/linux/mmzone.h a/include/linux/mmzone.h
--- linux-2.6.15/include/linux/mmzone.h 2006-01-03 12:21:10.000000000 +0900
+++ a/include/linux/mmzone.h 2006-01-27 10:32:47.000000000 +0900
@@ -322,6 +322,10 @@ void build_all_zonelists(void);
void wakeup_kswapd(struct zone *zone, int order);
int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
int classzone_idx, int alloc_flags);
+void read_lock_nr_zones(void);
+void read_unlock_nr_zones(void);
+void write_lock_nr_zones(unsigned long *flagsp);
+void write_unlock_nr_zones(unsigned long *flagsp);
#ifdef CONFIG_HAVE_MEMORY_PRESENT
void memory_present(int nid, unsigned long start, unsigned long end);
diff -urNp linux-2.6.15/mm/page_alloc.c a/mm/page_alloc.c
--- linux-2.6.15/mm/page_alloc.c 2006-01-03 12:21:10.000000000 +0900
+++ a/mm/page_alloc.c 2006-01-27 10:38:39.000000000 +0900
@@ -565,6 +565,7 @@ void drain_remote_pages(void)
unsigned long flags;
local_irq_save(flags);
+ read_lock_nr_zones();
for_each_zone(zone) {
struct per_cpu_pageset *pset;
@@ -582,6 +583,7 @@ void drain_remote_pages(void)
&pcp->list, 0);
}
}
+ read_unlock_nr_zones();
local_irq_restore(flags);
}
#endif
@@ -592,6 +594,7 @@ static void __drain_pages(unsigned int c
struct zone *zone;
int i;
+ read_lock_nr_zones();
for_each_zone(zone) {
struct per_cpu_pageset *pset;
@@ -604,6 +607,7 @@ static void __drain_pages(unsigned int c
&pcp->list, 0);
}
}
+ read_unlock_nr_zones();
}
#endif /* CONFIG_PM || CONFIG_HOTPLUG_CPU */
@@ -1080,8 +1084,10 @@ unsigned int nr_free_pages(void)
unsigned int sum = 0;
struct zone *zone;
+ read_lock_nr_zones();
for_each_zone(zone)
sum += zone->free_pages;
+ read_unlock_nr_zones();
return sum;
}
@@ -1331,6 +1337,7 @@ void show_free_areas(void)
unsigned long free;
struct zone *zone;
+ read_lock_nr_zones();
for_each_zone(zone) {
show_node(zone);
printk("%s per-cpu:", zone->name);
@@ -1427,6 +1434,7 @@ void show_free_areas(void)
spin_unlock_irqrestore(&zone->lock, flags);
printk("= %lukB\n", K(total));
}
+ read_unlock_nr_zones();
show_swap_cache_info();
}
@@ -1836,6 +1844,7 @@ static int __devinit process_zones(int c
{
struct zone *zone, *dzone;
+ read_lock_nr_zones();
for_each_zone(zone) {
zone->pageset[cpu] = kmalloc_node(sizeof(struct
per_cpu_pageset),
@@ -1845,6 +1854,7 @@ static int __devinit process_zones(int c
setup_pageset(zone->pageset[cpu], zone_batchsize(zone));
}
+ read_unlock_nr_zones();
return 0;
bad:
@@ -1854,6 +1864,7 @@ bad:
kfree(dzone->pageset[cpu]);
dzone->pageset[cpu] = NULL;
}
+ read_unlock_nr_zones();
return -ENOMEM;
}
@@ -1862,12 +1873,14 @@ static inline void free_zone_pagesets(in
#ifdef CONFIG_NUMA
struct zone *zone;
+ read_lock_nr_zones();
for_each_zone(zone) {
struct per_cpu_pageset *pset = zone_pcp(zone, cpu);
zone_pcp(zone, cpu) = NULL;
kfree(pset);
}
+ read_unlock_nr_zones();
#endif
}
@@ -2115,6 +2128,7 @@ static int frag_show(struct seq_file *m,
unsigned long flags;
int order;
+ read_lock_nr_zones();
for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
if (!zone->present_pages)
continue;
@@ -2126,6 +2140,7 @@ static int frag_show(struct seq_file *m,
spin_unlock_irqrestore(&zone->lock, flags);
seq_putc(m, '\n');
}
+ read_unlock_nr_zones();
return 0;
}
@@ -2146,6 +2161,7 @@ static int zoneinfo_show(struct seq_file
struct zone *node_zones = pgdat->node_zones;
unsigned long flags;
+ read_lock_nr_zones();
for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; zone++) {
int i;
@@ -2234,6 +2250,7 @@ static int zoneinfo_show(struct seq_file
spin_unlock_irqrestore(&zone->lock, flags);
seq_putc(m, '\n');
}
+ read_unlock_nr_zones();
return 0;
}
@@ -2426,6 +2443,7 @@ void setup_per_zone_pages_min(void)
struct zone *zone;
unsigned long flags;
+ read_lock_nr_zones();
/* Calculate total number of !ZONE_HIGHMEM pages */
for_each_zone(zone) {
if (!is_highmem(zone))
@@ -2466,6 +2484,7 @@ void setup_per_zone_pages_min(void)
zone->pages_high = zone->pages_min + tmp / 2;
spin_unlock_irqrestore(&zone->lru_lock, flags);
}
+ read_unlock_nr_zones();
}
/*
@@ -2629,3 +2648,52 @@ void *__init alloc_large_system_hash(con
return table;
}
+
+/*
+ * Avoiding addition/removal of zones while looking up zones by
+ * for_each_zone etc. These routines don't guard references from zonelists
+ * used in the page allocator.
+ */
+static spinlock_t nr_zones_lock = SPIN_LOCK_UNLOCKED;
+static int zones_readers = 0;
+static DECLARE_WAIT_QUEUE_HEAD(zones_waitqueue);
+
+void read_lock_nr_zones(void)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&nr_zones_lock, flags);
+ zones_readers++;
+ spin_unlock_irqrestore(&nr_zones_lock, flags);
+}
+
+void read_unlock_nr_zones(void)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&nr_zones_lock, flags);
+ zones_readers--;
+ if ((zones_readers == 0) && waitqueue_active(&zones_waitqueue))
+ wake_up(&zones_waitqueue);
+ spin_unlock_irqrestore(&nr_zones_lock, flags);
+}
+
+void write_lock_nr_zones(unsigned long *flagsp)
+{
+ DEFINE_WAIT(wait);
+
+ spin_lock_irqsave(&nr_zones_lock, *flagsp);
+ while (zones_readers) {
+ spin_unlock_irqrestore(&nr_zones_lock, *flagsp);
+ prepare_to_wait(&zones_waitqueue, &wait,
+ TASK_UNINTERRUPTIBLE);
+ schedule();
+ finish_wait(&zones_waitqueue, &wait);
+ spin_lock_irqsave(&nr_zones_lock, *flagsp);
+ }
+}
+
+void write_unlock_nr_zones(unsigned long *flagsp)
+{
+ spin_unlock_irqrestore(&nr_zones_lock, *flagsp);
+}
diff -urNp linux-2.6.15/mm/vmscan.c a/mm/vmscan.c
--- linux-2.6.15/mm/vmscan.c 2006-01-03 12:21:10.000000000 +0900
+++ a/mm/vmscan.c 2006-01-27 10:32:47.000000000 +0900
@@ -1261,7 +1261,9 @@ static int kswapd(void *p)
}
finish_wait(&pgdat->kswapd_wait, &wait);
+ read_lock_nr_zones();
balance_pgdat(pgdat, 0, order);
+ read_unlock_nr_zones();
}
return 0;
}
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