Hi Cody,
On 04/06/2013 04:33 AM, Cody P Schafer wrote:
In free_hot_cold_page(), we rely on pcp->batch remaining stable.
Updating it without being on the cpu owning the percpu pageset
potentially destroys this stability.
If cpu is off, can its pcp pageset be used in free_hot_code_page()?
Change for_each_cpu() to on_each_cpu() to fix.
Signed-off-by: Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 48f2faa..507db31 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5475,30 +5475,31 @@ int lowmem_reserve_ratio_sysctl_handler(ctl_table *table, int write,
return 0;
}
+static void _zone_set_pageset_highmark(void *data)
+{
+ struct zone *zone = data;
+ unsigned long high;
+ high = zone->managed_pages / percpu_pagelist_fraction;
+ setup_pagelist_highmark(
+ per_cpu_ptr(zone->pageset, smp_processor_id()), high);
+}
+
/*
* percpu_pagelist_fraction - changes the pcp->high for each zone on each
* cpu. It is the fraction of total pages in each zone that a hot per cpu pagelist
* can have before it gets flushed back to buddy allocator.
*/
-
int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
struct zone *zone;
- unsigned int cpu;
int ret;
ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (!write || (ret < 0))
return ret;
- for_each_populated_zone(zone) {
- for_each_possible_cpu(cpu) {
- unsigned long high;
- high = zone->managed_pages / percpu_pagelist_fraction;
- setup_pagelist_highmark(
- per_cpu_ptr(zone->pageset, cpu), high);
- }
- }
+ for_each_populated_zone(zone)
+ on_each_cpu(_zone_set_pageset_highmark, zone, true);
return 0;
}
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