summaryrefslogtreecommitdiffstats
path: root/debian/patches-rt/0210-mm-zsmalloc-copy-with-get_cpu_var-and-locking.patch
blob: f48595a8d3781a125c1cdd07090ffb1a33b774c2 (plain)
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
211
212
From 7e86ac4a42c020de9b35b02a3ef02f2fc0dee2ed Mon Sep 17 00:00:00 2001
From: Mike Galbraith <umgwanakikbuti@gmail.com>
Date: Tue, 22 Mar 2016 11:16:09 +0100
Subject: [PATCH 210/323] mm/zsmalloc: copy with get_cpu_var() and locking
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz

get_cpu_var() disables preemption and triggers a might_sleep() splat later.
This is replaced with get_locked_var().
This bitspinlocks are replaced with a proper mutex which requires a slightly
larger struct to allocate.

Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
[bigeasy: replace the bitspin_lock() with a mutex, get_locked_var(). Mike then
fixed the size magic]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 mm/zsmalloc.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 79 insertions(+), 6 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index c18dc8e61d35..7dad2ff3e778 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -57,6 +57,7 @@
 #include <linux/wait.h>
 #include <linux/pagemap.h>
 #include <linux/fs.h>
+#include <linux/local_lock.h>
 
 #define ZSPAGE_MAGIC	0x58
 
@@ -77,6 +78,20 @@
 
 #define ZS_HANDLE_SIZE (sizeof(unsigned long))
 
+#ifdef CONFIG_PREEMPT_RT
+
+struct zsmalloc_handle {
+	unsigned long addr;
+	struct mutex lock;
+};
+
+#define ZS_HANDLE_ALLOC_SIZE (sizeof(struct zsmalloc_handle))
+
+#else
+
+#define ZS_HANDLE_ALLOC_SIZE (sizeof(unsigned long))
+#endif
+
 /*
  * Object location (<PFN>, <obj_idx>) is encoded as
  * a single (unsigned long) handle value.
@@ -293,6 +308,7 @@ struct zspage {
 };
 
 struct mapping_area {
+	local_lock_t lock;
 	char *vm_buf; /* copy buffer for objects that span pages */
 	char *vm_addr; /* address of kmap_atomic()'ed pages */
 	enum zs_mapmode vm_mm; /* mapping mode */
@@ -322,7 +338,7 @@ static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) {}
 
 static int create_cache(struct zs_pool *pool)
 {
-	pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
+	pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_ALLOC_SIZE,
 					0, 0, NULL);
 	if (!pool->handle_cachep)
 		return 1;
@@ -346,9 +362,26 @@ static void destroy_cache(struct zs_pool *pool)
 
 static unsigned long cache_alloc_handle(struct zs_pool *pool, gfp_t gfp)
 {
-	return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
-			gfp & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
+	void *p;
+
+	p = kmem_cache_alloc(pool->handle_cachep,
+			     gfp & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
+#ifdef CONFIG_PREEMPT_RT
+	if (p) {
+		struct zsmalloc_handle *zh = p;
+
+		mutex_init(&zh->lock);
+	}
+#endif
+	return (unsigned long)p;
+}
+
+#ifdef CONFIG_PREEMPT_RT
+static struct zsmalloc_handle *zs_get_pure_handle(unsigned long handle)
+{
+	return (void *)(handle &~((1 << OBJ_TAG_BITS) - 1));
 }
+#endif
 
 static void cache_free_handle(struct zs_pool *pool, unsigned long handle)
 {
@@ -368,12 +401,18 @@ static void cache_free_zspage(struct zs_pool *pool, struct zspage *zspage)
 
 static void record_obj(unsigned long handle, unsigned long obj)
 {
+#ifdef CONFIG_PREEMPT_RT
+	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
+
+	WRITE_ONCE(zh->addr, obj);
+#else
 	/*
 	 * lsb of @obj represents handle lock while other bits
 	 * represent object value the handle is pointing so
 	 * updating shouldn't do store tearing.
 	 */
 	WRITE_ONCE(*(unsigned long *)handle, obj);
+#endif
 }
 
 /* zpool driver */
@@ -455,7 +494,10 @@ MODULE_ALIAS("zpool-zsmalloc");
 #endif /* CONFIG_ZPOOL */
 
 /* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
-static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
+static DEFINE_PER_CPU(struct mapping_area, zs_map_area) = {
+	/* XXX remove this and use a spin_lock_t in pin_tag() */
+	.lock	= INIT_LOCAL_LOCK(lock),
+};
 
 static bool is_zspage_isolated(struct zspage *zspage)
 {
@@ -865,7 +907,13 @@ static unsigned long location_to_obj(struct page *page, unsigned int obj_idx)
 
 static unsigned long handle_to_obj(unsigned long handle)
 {
+#ifdef CONFIG_PREEMPT_RT
+	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
+
+	return zh->addr;
+#else
 	return *(unsigned long *)handle;
+#endif
 }
 
 static unsigned long obj_to_head(struct page *page, void *obj)
@@ -879,22 +927,46 @@ static unsigned long obj_to_head(struct page *page, void *obj)
 
 static inline int testpin_tag(unsigned long handle)
 {
+#ifdef CONFIG_PREEMPT_RT
+	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
+
+	return mutex_is_locked(&zh->lock);
+#else
 	return bit_spin_is_locked(HANDLE_PIN_BIT, (unsigned long *)handle);
+#endif
 }
 
 static inline int trypin_tag(unsigned long handle)
 {
+#ifdef CONFIG_PREEMPT_RT
+	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
+
+	return mutex_trylock(&zh->lock);
+#else
 	return bit_spin_trylock(HANDLE_PIN_BIT, (unsigned long *)handle);
+#endif
 }
 
 static void pin_tag(unsigned long handle) __acquires(bitlock)
 {
+#ifdef CONFIG_PREEMPT_RT
+	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
+
+	return mutex_lock(&zh->lock);
+#else
 	bit_spin_lock(HANDLE_PIN_BIT, (unsigned long *)handle);
+#endif
 }
 
 static void unpin_tag(unsigned long handle) __releases(bitlock)
 {
+#ifdef CONFIG_PREEMPT_RT
+	struct zsmalloc_handle *zh = zs_get_pure_handle(handle);
+
+	return mutex_unlock(&zh->lock);
+#else
 	bit_spin_unlock(HANDLE_PIN_BIT, (unsigned long *)handle);
+#endif
 }
 
 static void reset_page(struct page *page)
@@ -1278,7 +1350,8 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
 	class = pool->size_class[class_idx];
 	off = (class->size * obj_idx) & ~PAGE_MASK;
 
-	area = &get_cpu_var(zs_map_area);
+	local_lock(&zs_map_area.lock);
+	area = this_cpu_ptr(&zs_map_area);
 	area->vm_mm = mm;
 	if (off + class->size <= PAGE_SIZE) {
 		/* this object is contained entirely within a page */
@@ -1332,7 +1405,7 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
 
 		__zs_unmap_object(area, pages, off, class->size);
 	}
-	put_cpu_var(zs_map_area);
+	local_unlock(&zs_map_area.lock);
 
 	migrate_read_unlock(zspage);
 	unpin_tag(handle);
-- 
2.43.0