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authorCody P Schafer <cody@linux.vnet.ibm.com>2013-07-03 22:01:29 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-03 23:07:26 (GMT)
commitc8e251fadc6220261f6e0c6b8a4f1cdf27626165 (patch)
tree434ddbf9a6fd9e9f62e8d04e8d7be8a2a0e19a59 /mm/page_alloc.c
parent4008bab7b3969ad9f9dd1d02096a3f0aa5610bd2 (diff)
downloadlinux-c8e251fadc6220261f6e0c6b8a4f1cdf27626165.tar.xz
mm/page_alloc: prevent concurrent updaters of pcp ->batch and ->high
Because we are going to rely upon a careful transision between old and new ->high and ->batch values using memory barriers and will remove stop_machine(), we need to prevent multiple updaters from interweaving their memory writes. Add a simple mutex to protect both update loops. Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d4bcc20..8d43357 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -65,6 +65,9 @@
#include <asm/div64.h>
#include "internal.h"
+/* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
+static DEFINE_MUTEX(pcp_batch_high_lock);
+
#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
DEFINE_PER_CPU(int, numa_node);
EXPORT_PER_CPU_SYMBOL(numa_node);
@@ -5557,6 +5560,8 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write,
ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (!write || (ret < 0))
return ret;
+
+ mutex_lock(&pcp_batch_high_lock);
for_each_populated_zone(zone) {
for_each_possible_cpu(cpu) {
unsigned long high;
@@ -5565,6 +5570,7 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write,
per_cpu_ptr(zone->pageset, cpu), high);
}
}
+ mutex_unlock(&pcp_batch_high_lock);
return 0;
}
@@ -6078,7 +6084,9 @@ static int __meminit __zone_pcp_update(void *data)
void __meminit zone_pcp_update(struct zone *zone)
{
+ mutex_lock(&pcp_batch_high_lock);
stop_machine(__zone_pcp_update, zone, NULL);
+ mutex_unlock(&pcp_batch_high_lock);
}
#endif