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
|
From: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 28 May 2018 15:24:20 +0200
Subject: [PATCH 072/353] Split IRQ-off and zone->lock while freeing pages from
PCP list #1
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=9fd68ce8dfdfd97a4178efdda9dd37014f62b1d5
Split the IRQ-off section while accessing the PCP list from zone->lock
while freeing pages.
Introcude isolate_pcp_pages() which separates the pages from the PCP
list onto a temporary list and then free the temporary list via
free_pcppages_bulk().
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
mm/page_alloc.c | 82 +++++++++++++++++++++++++++++++------------------
1 file changed, 52 insertions(+), 30 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4553cc848abc..d5fc6a1c79a5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1096,7 +1096,7 @@ static inline void prefetch_buddy(struct page *page)
}
/*
- * Frees a number of pages from the PCP lists
+ * Frees a number of pages which have been collected from the pcp lists.
* Assumes all pages on list are in same zone, and of same order.
* count is the number of pages to free.
*
@@ -1107,14 +1107,41 @@ static inline void prefetch_buddy(struct page *page)
* pinned" detection logic.
*/
static void free_pcppages_bulk(struct zone *zone, int count,
- struct per_cpu_pages *pcp)
+ struct list_head *head)
+{
+ bool isolated_pageblocks;
+ struct page *page, *tmp;
+ unsigned long flags;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ isolated_pageblocks = has_isolate_pageblock(zone);
+
+ /*
+ * Use safe version since after __free_one_page(),
+ * page->lru.next will not point to original list.
+ */
+ list_for_each_entry_safe(page, tmp, head, lru) {
+ int mt = get_pcppage_migratetype(page);
+ /* MIGRATE_ISOLATE page should not go to pcplists */
+ VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
+ /* Pageblock could have been isolated meanwhile */
+ if (unlikely(isolated_pageblocks))
+ mt = get_pageblock_migratetype(page);
+
+ __free_one_page(page, page_to_pfn(page), zone, 0, mt);
+ trace_mm_page_pcpu_drain(page, 0, mt);
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+}
+
+static void isolate_pcp_pages(int count, struct per_cpu_pages *pcp,
+ struct list_head *dst)
+
{
int migratetype = 0;
int batch_free = 0;
int prefetch_nr = 0;
- bool isolated_pageblocks;
- struct page *page, *tmp;
- LIST_HEAD(head);
+ struct page *page;
/*
* Ensure proper count is passed which otherwise would stuck in the
@@ -1151,7 +1178,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
if (bulkfree_pcp_prepare(page))
continue;
- list_add_tail(&page->lru, &head);
+ list_add_tail(&page->lru, dst);
/*
* We are going to put the page back to the global
@@ -1166,26 +1193,6 @@ static void free_pcppages_bulk(struct zone *zone, int count,
prefetch_buddy(page);
} while (--count && --batch_free && !list_empty(list));
}
-
- spin_lock(&zone->lock);
- isolated_pageblocks = has_isolate_pageblock(zone);
-
- /*
- * Use safe version since after __free_one_page(),
- * page->lru.next will not point to original list.
- */
- list_for_each_entry_safe(page, tmp, &head, lru) {
- int mt = get_pcppage_migratetype(page);
- /* MIGRATE_ISOLATE page should not go to pcplists */
- VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
- /* Pageblock could have been isolated meanwhile */
- if (unlikely(isolated_pageblocks))
- mt = get_pageblock_migratetype(page);
-
- __free_one_page(page, page_to_pfn(page), zone, 0, mt);
- trace_mm_page_pcpu_drain(page, 0, mt);
- }
- spin_unlock(&zone->lock);
}
static void free_one_page(struct zone *zone,
@@ -2546,13 +2553,18 @@ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
{
unsigned long flags;
int to_drain, batch;
+ LIST_HEAD(dst);
local_irq_save(flags);
batch = READ_ONCE(pcp->batch);
to_drain = min(pcp->count, batch);
if (to_drain > 0)
- free_pcppages_bulk(zone, to_drain, pcp);
+ isolate_pcp_pages(to_drain, pcp, &dst);
+
local_irq_restore(flags);
+
+ if (to_drain > 0)
+ free_pcppages_bulk(zone, to_drain, &dst);
}
#endif
@@ -2568,14 +2580,21 @@ static void drain_pages_zone(unsigned int cpu, struct zone *zone)
unsigned long flags;
struct per_cpu_pageset *pset;
struct per_cpu_pages *pcp;
+ LIST_HEAD(dst);
+ int count;
local_irq_save(flags);
pset = per_cpu_ptr(zone->pageset, cpu);
pcp = &pset->pcp;
- if (pcp->count)
- free_pcppages_bulk(zone, pcp->count, pcp);
+ count = pcp->count;
+ if (count)
+ isolate_pcp_pages(count, pcp, &dst);
+
local_irq_restore(flags);
+
+ if (count)
+ free_pcppages_bulk(zone, count, &dst);
}
/*
@@ -2797,7 +2816,10 @@ static void free_unref_page_commit(struct page *page, unsigned long pfn)
pcp->count++;
if (pcp->count >= pcp->high) {
unsigned long batch = READ_ONCE(pcp->batch);
- free_pcppages_bulk(zone, batch, pcp);
+ LIST_HEAD(dst);
+
+ isolate_pcp_pages(batch, pcp, &dst);
+ free_pcppages_bulk(zone, batch, &dst);
}
}
|
