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From a066e44619e1a6f661cd861015a5b658adead8bc Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 3 Jul 2009 08:30:13 -0500
Subject: [PATCH 180/323] mm/vmstat: Protect per cpu variables with preempt
disable on RT
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
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>
---
include/linux/vmstat.h | 4 ++++
mm/vmstat.c | 12 ++++++++++++
2 files changed, 16 insertions(+)
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 322dcbfcc933..9a3a10ea3e3c 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -63,7 +63,9 @@ 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)
@@ -73,7 +75,9 @@ 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)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index e292e63afebf..598e9317c7e0 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -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);
@@ -346,6 +348,7 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
delta >>= PAGE_SHIFT;
}
+ preempt_disable_rt();
x = delta + __this_cpu_read(*p);
t = __this_cpu_read(pcp->stat_threshold);
@@ -355,6 +358,7 @@ 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);
@@ -387,6 +391,7 @@ 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)) {
@@ -395,6 +400,7 @@ 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)
@@ -405,6 +411,7 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
+ preempt_disable_rt();
v = __this_cpu_inc_return(*p);
t = __this_cpu_read(pcp->stat_threshold);
if (unlikely(v > t)) {
@@ -413,6 +420,7 @@ 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)
@@ -433,6 +441,7 @@ 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)) {
@@ -441,6 +450,7 @@ 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)
@@ -451,6 +461,7 @@ void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
+ preempt_disable_rt();
v = __this_cpu_dec_return(*p);
t = __this_cpu_read(pcp->stat_threshold);
if (unlikely(v < - t)) {
@@ -459,6 +470,7 @@ 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)
--
2.43.0
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