From: Cody P Schafer <cody@linux.vnet.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Gilad Ben-Yossef <gilad@benyossef.com>,
Simon Jeons <simon.jeons@gmail.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Mel Gorman <mgorman@suse.de>, Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Cody P Schafer <cody@linux.vnet.ibm.com>
Subject: [PATCH v2 02/10] mm/page_alloc: prevent concurrent updaters of pcp ->batch and ->high
Date: Tue, 9 Apr 2013 16:28:11 -0700 [thread overview]
Message-ID: <1365550099-6795-3-git-send-email-cody@linux.vnet.ibm.com> (raw)
In-Reply-To: <1365550099-6795-1-git-send-email-cody@linux.vnet.ibm.com>
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>
---
mm/page_alloc.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5877cf0..d259599 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -64,6 +64,9 @@
#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);
@@ -5491,6 +5494,8 @@ 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;
@@ -5499,6 +5504,7 @@ 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;
}
@@ -6012,7 +6018,9 @@ 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
--
1.8.2
next prev parent reply other threads:[~2013-04-09 23:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-09 23:28 [PATCH v2 00/10] mm: fixup changers of per cpu pageset's ->high and ->batch Cody P Schafer
2013-04-09 23:28 ` [PATCH v2 01/10] mm/page_alloc: factor out setting of pcp->high and pcp->batch Cody P Schafer
2013-04-09 23:28 ` Cody P Schafer [this message]
2013-04-09 23:28 ` [PATCH v2 03/10] mm/page_alloc: insert memory barriers to allow async update of pcp batch and high Cody P Schafer
2013-04-10 6:19 ` Gilad Ben-Yossef
2013-04-10 6:22 ` Gilad Ben-Yossef
2013-04-10 18:31 ` Cody P Schafer
2013-04-09 23:28 ` [PATCH v2 04/10] mm/page_alloc: convert zone_pcp_update() to rely on memory barriers instead of stop_machine() Cody P Schafer
2013-04-09 23:28 ` [PATCH v2 05/10] mm/page_alloc: when handling percpu_pagelist_fraction, don't unneedly recalulate high Cody P Schafer
2013-04-09 23:28 ` [PATCH v2 06/10] mm/page_alloc: factor setup_pageset() into pageset_init() and pageset_set_batch() Cody P Schafer
2013-04-09 23:28 ` [PATCH v2 07/10] mm/page_alloc: relocate comment to be directly above code it refers to Cody P Schafer
2013-04-09 23:28 ` [PATCH v2 08/10] mm/page_alloc: factor zone_pageset_init() out of setup_zone_pageset() Cody P Schafer
2013-04-09 23:28 ` [PATCH v2 09/10] mm/page_alloc: in zone_pcp_update(), uze zone_pageset_init() Cody P Schafer
2013-04-09 23:28 ` [PATCH v2 10/10] mm/page_alloc: rename setup_pagelist_highmark() to match naming of pageset_set_batch() Cody P Schafer
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