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mm/vmstat: Protect per cpu variables with preempt disable on RT 

Disable preemption on -RT for the vmstat code. On vanila the code runs in
IRQ-off regions while on -RT it is not. "preempt_disable" ensures that the
same ressources is not updated in parallel due to preemption.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Ingo Molnar 2009-07-03 08:30:13 -05:00 committed by Alibek Omarov
parent 179fc64984
commit 8dd0922414
2 changed files with 16 additions and 0 deletions
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4
include/linux/vmstat.h
View File

@ -54,7 +54,9 @@ DECLARE_PER_CPU(struct vm_event_state, vm_event_states);
*/
static inline void __count_vm_event(enum vm_event_item item)
{
preempt_disable_rt();
raw_cpu_inc(vm_event_states.event[item]);
preempt_enable_rt();
}
static inline void count_vm_event(enum vm_event_item item)
@ -64,7 +66,9 @@ static inline void count_vm_event(enum vm_event_item item)
static inline void __count_vm_events(enum vm_event_item item, long delta)
{
preempt_disable_rt();
raw_cpu_add(vm_event_states.event[item], delta);
preempt_enable_rt();
}
static inline void count_vm_events(enum vm_event_item item, long delta)

12
mm/vmstat.c
View File

@ -321,6 +321,7 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
long x;
long t;
preempt_disable_rt();
x = delta + __this_cpu_read(*p);
t = __this_cpu_read(pcp->stat_threshold);
@ -330,6 +331,7 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
x = 0;
}
__this_cpu_write(*p, x);
preempt_enable_rt();
}
EXPORT_SYMBOL(__mod_zone_page_state);
@ -341,6 +343,7 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
long x;
long t;
preempt_disable_rt();
x = delta + __this_cpu_read(*p);
t = __this_cpu_read(pcp->stat_threshold);
@ -350,6 +353,7 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
x = 0;
}
__this_cpu_write(*p, x);
preempt_enable_rt();
}
EXPORT_SYMBOL(__mod_node_page_state);
@ -382,6 +386,7 @@ void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
s8 __percpu *p = pcp->vm_stat_diff + item;
s8 v, t;
preempt_disable_rt();
v = __this_cpu_inc_return(*p);
t = __this_cpu_read(pcp->stat_threshold);
if (unlikely(v > t)) {
@ -390,6 +395,7 @@ void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
zone_page_state_add(v + overstep, zone, item);
__this_cpu_write(*p, -overstep);
}
preempt_enable_rt();
}
void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
@ -398,6 +404,7 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
s8 __percpu *p = pcp->vm_node_stat_diff + item;
s8 v, t;
preempt_disable_rt();
v = __this_cpu_inc_return(*p);
t = __this_cpu_read(pcp->stat_threshold);
if (unlikely(v > t)) {
@ -406,6 +413,7 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
node_page_state_add(v + overstep, pgdat, item);
__this_cpu_write(*p, -overstep);
}
preempt_enable_rt();
}
void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
@ -426,6 +434,7 @@ void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
s8 __percpu *p = pcp->vm_stat_diff + item;
s8 v, t;
preempt_disable_rt();
v = __this_cpu_dec_return(*p);
t = __this_cpu_read(pcp->stat_threshold);
if (unlikely(v < - t)) {
@ -434,6 +443,7 @@ void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
zone_page_state_add(v - overstep, zone, item);
__this_cpu_write(*p, overstep);
}
preempt_enable_rt();
}
void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
@ -442,6 +452,7 @@ void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
s8 __percpu *p = pcp->vm_node_stat_diff + item;
s8 v, t;
preempt_disable_rt();
v = __this_cpu_dec_return(*p);
t = __this_cpu_read(pcp->stat_threshold);
if (unlikely(v < - t)) {
@ -450,6 +461,7 @@ void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
node_page_state_add(v - overstep, pgdat, item);
__this_cpu_write(*p, overstep);
}
preempt_enable_rt();
}
void __dec_zone_page_state(struct page *page, enum zone_stat_item item)