1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
From 1398d3c431f6fd53914f1b71dd30732092e6baa7 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 3 Jul 2009 08:29:37 -0500
Subject: [PATCH 111/191] mm: page_alloc: Use a local_lock instead of explicit
local_irq_save().
The page-allocator disables interrupts for a few reasons:
- Decouple interrupt the irqsave operation from spin_lock() so it can be
extended over the actual lock region and cover other areas. Areas like
counters increments where the preemptible version can be avoided.
- Access to the per-CPU pcp from struct zone.
Replace the irqsave with a local-lock. The counters are expected to be
always modified with disabled preemption and no access from interrupt
context.
Contains fixes from:
Peter Zijlstra <a.p.zijlstra@chello.nl>
Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
mm/page_alloc.c | 49 ++++++++++++++++++++++++++++++-------------------
1 file changed, 30 insertions(+), 19 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index db713dd3e08e..72993fb19c99 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -62,6 +62,7 @@
#include <linux/hugetlb.h>
#include <linux/sched/rt.h>
#include <linux/sched/mm.h>
+#include <linux/local_lock.h>
#include <linux/page_owner.h>
#include <linux/kthread.h>
#include <linux/memcontrol.h>
@@ -363,6 +364,13 @@ EXPORT_SYMBOL(nr_online_nodes);
int page_group_by_mobility_disabled __read_mostly;
+struct pa_lock {
+ local_lock_t l;
+};
+static DEFINE_PER_CPU(struct pa_lock, pa_lock) = {
+ .l = INIT_LOCAL_LOCK(l),
+};
+
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
/*
* During boot we initialize deferred pages on-demand, as needed, but once
@@ -1541,11 +1549,11 @@ static void __free_pages_ok(struct page *page, unsigned int order,
return;
migratetype = get_pfnblock_migratetype(page, pfn);
- local_irq_save(flags);
+ local_lock_irqsave(&pa_lock.l, flags);
__count_vm_events(PGFREE, 1 << order);
free_one_page(page_zone(page), page, pfn, order, migratetype,
fpi_flags);
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
}
void __free_pages_core(struct page *page, unsigned int order)
@@ -2962,12 +2970,12 @@ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
unsigned long flags;
int to_drain, batch;
- local_irq_save(flags);
+ local_lock_irqsave(&pa_lock.l, flags);
batch = READ_ONCE(pcp->batch);
to_drain = min(pcp->count, batch);
if (to_drain > 0)
free_pcppages_bulk(zone, to_drain, pcp);
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
}
#endif
@@ -2984,13 +2992,13 @@ static void drain_pages_zone(unsigned int cpu, struct zone *zone)
struct per_cpu_pageset *pset;
struct per_cpu_pages *pcp;
- local_irq_save(flags);
+ local_lock_irqsave(&pa_lock.l, flags);
pset = per_cpu_ptr(zone->pageset, cpu);
pcp = &pset->pcp;
if (pcp->count)
free_pcppages_bulk(zone, pcp->count, pcp);
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
}
/*
@@ -3253,9 +3261,9 @@ void free_unref_page(struct page *page)
if (!free_unref_page_prepare(page, pfn))
return;
- local_irq_save(flags);
+ local_lock_irqsave(&pa_lock.l, flags);
free_unref_page_commit(page, pfn);
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
}
/*
@@ -3275,7 +3283,7 @@ void free_unref_page_list(struct list_head *list)
set_page_private(page, pfn);
}
- local_irq_save(flags);
+ local_lock_irqsave(&pa_lock.l, flags);
list_for_each_entry_safe(page, next, list, lru) {
unsigned long pfn = page_private(page);
@@ -3288,12 +3296,12 @@ void free_unref_page_list(struct list_head *list)
* a large list of pages to free.
*/
if (++batch_count == SWAP_CLUSTER_MAX) {
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
batch_count = 0;
- local_irq_save(flags);
+ local_lock_irqsave(&pa_lock.l, flags);
}
}
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
}
/*
@@ -3449,7 +3457,7 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
struct page *page;
unsigned long flags;
- local_irq_save(flags);
+ local_lock_irqsave(&pa_lock.l, flags);
pcp = &this_cpu_ptr(zone->pageset)->pcp;
list = &pcp->lists[migratetype];
page = __rmqueue_pcplist(zone, migratetype, alloc_flags, pcp, list);
@@ -3457,7 +3465,7 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
__count_zid_vm_events(PGALLOC, page_zonenum(page), 1);
zone_statistics(preferred_zone, zone);
}
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
return page;
}
@@ -3491,7 +3499,9 @@ struct page *rmqueue(struct zone *preferred_zone,
* allocate greater than order-1 page units with __GFP_NOFAIL.
*/
WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
- spin_lock_irqsave(&zone->lock, flags);
+
+ local_lock_irqsave(&pa_lock.l, flags);
+ spin_lock(&zone->lock);
do {
page = NULL;
@@ -3512,12 +3522,13 @@ struct page *rmqueue(struct zone *preferred_zone,
spin_unlock(&zone->lock);
if (!page)
goto failed;
+
__mod_zone_freepage_state(zone, -(1 << order),
get_pcppage_migratetype(page));
__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
zone_statistics(preferred_zone, zone);
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
out:
/* Separate test+clear to avoid unnecessary atomics */
@@ -3530,7 +3541,7 @@ struct page *rmqueue(struct zone *preferred_zone,
return page;
failed:
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
return NULL;
}
@@ -8810,7 +8821,7 @@ void zone_pcp_reset(struct zone *zone)
struct per_cpu_pageset *pset;
/* avoid races with drain_pages() */
- local_irq_save(flags);
+ local_lock_irqsave(&pa_lock.l, flags);
if (zone->pageset != &boot_pageset) {
for_each_online_cpu(cpu) {
pset = per_cpu_ptr(zone->pageset, cpu);
@@ -8819,7 +8830,7 @@ void zone_pcp_reset(struct zone *zone)
free_percpu(zone->pageset);
zone->pageset = &boot_pageset;
}
- local_irq_restore(flags);
+ local_unlock_irqrestore(&pa_lock.l, flags);
}
#ifdef CONFIG_MEMORY_HOTREMOVE
--
2.19.1
|
