1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SHRINKER_H 2 #ifndef _LINUX_SHRINKER_H
3 #define _LINUX_SHRINKER_H 3 #define _LINUX_SHRINKER_H
4 4
5 #include <linux/atomic.h> 5 #include <linux/atomic.h>
6 #include <linux/types.h> 6 #include <linux/types.h>
7 #include <linux/refcount.h> <<
8 #include <linux/completion.h> <<
9 <<
10 #define SHRINKER_UNIT_BITS BITS_PER_LONG <<
11 <<
12 /* <<
13 * Bitmap and deferred work of shrinker::id co <<
14 * shrinkers, which have elements charged to t <<
15 */ <<
16 struct shrinker_info_unit { <<
17 atomic_long_t nr_deferred[SHRINKER_UNI <<
18 DECLARE_BITMAP(map, SHRINKER_UNIT_BITS <<
19 }; <<
20 <<
21 struct shrinker_info { <<
22 struct rcu_head rcu; <<
23 int map_nr_max; <<
24 struct shrinker_info_unit *unit[]; <<
25 }; <<
26 7
27 /* 8 /*
28 * This struct is used to pass information fro 9 * This struct is used to pass information from page reclaim to the shrinkers.
29 * We consolidate the values for easier extens 10 * We consolidate the values for easier extension later.
30 * 11 *
31 * The 'gfpmask' refers to the allocation we a 12 * The 'gfpmask' refers to the allocation we are currently trying to
32 * fulfil. 13 * fulfil.
33 */ 14 */
34 struct shrink_control { 15 struct shrink_control {
35 gfp_t gfp_mask; 16 gfp_t gfp_mask;
36 17
37 /* current node being shrunk (for NUMA 18 /* current node being shrunk (for NUMA aware shrinkers) */
38 int nid; 19 int nid;
39 20
40 /* 21 /*
41 * How many objects scan_objects shoul 22 * How many objects scan_objects should scan and try to reclaim.
42 * This is reset before every call, so 23 * This is reset before every call, so it is safe for callees
43 * to modify. 24 * to modify.
44 */ 25 */
45 unsigned long nr_to_scan; 26 unsigned long nr_to_scan;
46 27
47 /* 28 /*
48 * How many objects did scan_objects p 29 * How many objects did scan_objects process?
49 * This defaults to nr_to_scan before 30 * This defaults to nr_to_scan before every call, but the callee
50 * should track its actual progress. 31 * should track its actual progress.
51 */ 32 */
52 unsigned long nr_scanned; 33 unsigned long nr_scanned;
53 34
54 /* current memcg being shrunk (for mem 35 /* current memcg being shrunk (for memcg aware shrinkers) */
55 struct mem_cgroup *memcg; 36 struct mem_cgroup *memcg;
56 }; 37 };
57 38
58 #define SHRINK_STOP (~0UL) 39 #define SHRINK_STOP (~0UL)
59 #define SHRINK_EMPTY (~0UL - 1) 40 #define SHRINK_EMPTY (~0UL - 1)
60 /* 41 /*
61 * A callback you can register to apply pressu 42 * A callback you can register to apply pressure to ageable caches.
62 * 43 *
63 * @count_objects should return the number of 44 * @count_objects should return the number of freeable items in the cache. If
64 * there are no objects to free, it should ret 45 * there are no objects to free, it should return SHRINK_EMPTY, while 0 is
65 * returned in cases of the number of freeable 46 * returned in cases of the number of freeable items cannot be determined
66 * or shrinker should skip this cache for this 47 * or shrinker should skip this cache for this time (e.g., their number
67 * is below shrinkable limit). No deadlock che 48 * is below shrinkable limit). No deadlock checks should be done during the
68 * count callback - the shrinker relies on agg 49 * count callback - the shrinker relies on aggregating scan counts that couldn't
69 * be executed due to potential deadlocks to b 50 * be executed due to potential deadlocks to be run at a later call when the
70 * deadlock condition is no longer pending. 51 * deadlock condition is no longer pending.
71 * 52 *
72 * @scan_objects will only be called if @count 53 * @scan_objects will only be called if @count_objects returned a non-zero
73 * value for the number of freeable objects. T 54 * value for the number of freeable objects. The callout should scan the cache
74 * and attempt to free items from the cache. I 55 * and attempt to free items from the cache. It should then return the number
75 * of objects freed during the scan, or SHRINK 56 * of objects freed during the scan, or SHRINK_STOP if progress cannot be made
76 * due to potential deadlocks. If SHRINK_STOP 57 * due to potential deadlocks. If SHRINK_STOP is returned, then no further
77 * attempts to call the @scan_objects will be 58 * attempts to call the @scan_objects will be made from the current reclaim
78 * context. 59 * context.
79 * 60 *
80 * @flags determine the shrinker abilities, li 61 * @flags determine the shrinker abilities, like numa awareness
81 */ 62 */
82 struct shrinker { 63 struct shrinker {
83 unsigned long (*count_objects)(struct 64 unsigned long (*count_objects)(struct shrinker *,
84 struct 65 struct shrink_control *sc);
85 unsigned long (*scan_objects)(struct s 66 unsigned long (*scan_objects)(struct shrinker *,
86 struct s 67 struct shrink_control *sc);
87 68
88 long batch; /* reclaim batch size, 69 long batch; /* reclaim batch size, 0 = default */
89 int seeks; /* seeks to recreate a 70 int seeks; /* seeks to recreate an obj */
90 unsigned flags; 71 unsigned flags;
91 72
92 /* <<
93 * The reference count of this shrinke <<
94 * initial refcount of 1, then the loo <<
95 * to use it via shrinker_try_get(). L <<
96 * the initial refcount will be discar <<
97 * asynchronously via RCU after its re <<
98 */ <<
99 refcount_t refcount; <<
100 struct completion done; /* use to wait <<
101 struct rcu_head rcu; <<
102 <<
103 void *private_data; <<
104 <<
105 /* These are for internal use */ 73 /* These are for internal use */
106 struct list_head list; 74 struct list_head list;
107 #ifdef CONFIG_MEMCG 75 #ifdef CONFIG_MEMCG
108 /* ID in shrinker_idr */ 76 /* ID in shrinker_idr */
109 int id; 77 int id;
110 #endif 78 #endif
111 #ifdef CONFIG_SHRINKER_DEBUG 79 #ifdef CONFIG_SHRINKER_DEBUG
112 int debugfs_id; 80 int debugfs_id;
113 const char *name; 81 const char *name;
114 struct dentry *debugfs_entry; 82 struct dentry *debugfs_entry;
115 #endif 83 #endif
116 /* objs pending delete, per node */ 84 /* objs pending delete, per node */
117 atomic_long_t *nr_deferred; 85 atomic_long_t *nr_deferred;
118 }; 86 };
119 #define DEFAULT_SEEKS 2 /* A good number if yo 87 #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
120 88
121 /* Internal flags */ !! 89 /* Flags */
122 #define SHRINKER_REGISTERED BIT(0) !! 90 #define SHRINKER_REGISTERED (1 << 0)
123 #define SHRINKER_ALLOCATED BIT(1) !! 91 #define SHRINKER_NUMA_AWARE (1 << 1)
124 !! 92 #define SHRINKER_MEMCG_AWARE (1 << 2)
125 /* Flags for users to use */ <<
126 #define SHRINKER_NUMA_AWARE BIT(2) <<
127 #define SHRINKER_MEMCG_AWARE BIT(3) <<
128 /* 93 /*
129 * It just makes sense when the shrinker is al 94 * It just makes sense when the shrinker is also MEMCG_AWARE for now,
130 * non-MEMCG_AWARE shrinker should not have th 95 * non-MEMCG_AWARE shrinker should not have this flag set.
131 */ 96 */
132 #define SHRINKER_NONSLAB BIT(4) !! 97 #define SHRINKER_NONSLAB (1 << 3)
133 98
134 __printf(2, 3) !! 99 extern int __printf(2, 3) prealloc_shrinker(struct shrinker *shrinker,
135 struct shrinker *shrinker_alloc(unsigned int f !! 100 const char *fmt, ...);
136 void shrinker_register(struct shrinker *shrink !! 101 extern void register_shrinker_prepared(struct shrinker *shrinker);
137 void shrinker_free(struct shrinker *shrinker); !! 102 extern int __printf(2, 3) register_shrinker(struct shrinker *shrinker,
138 !! 103 const char *fmt, ...);
139 static inline bool shrinker_try_get(struct shr !! 104 extern void unregister_shrinker(struct shrinker *shrinker);
140 { !! 105 extern void free_prealloced_shrinker(struct shrinker *shrinker);
141 return refcount_inc_not_zero(&shrinker !! 106 extern void synchronize_shrinkers(void);
142 } <<
143 <<
144 static inline void shrinker_put(struct shrinke <<
145 { <<
146 if (refcount_dec_and_test(&shrinker->r <<
147 complete(&shrinker->done); <<
148 } <<
149 107
150 #ifdef CONFIG_SHRINKER_DEBUG 108 #ifdef CONFIG_SHRINKER_DEBUG
>> 109 extern int shrinker_debugfs_add(struct shrinker *shrinker);
>> 110 extern struct dentry *shrinker_debugfs_remove(struct shrinker *shrinker);
151 extern int __printf(2, 3) shrinker_debugfs_ren 111 extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker *shrinker,
152 112 const char *fmt, ...);
153 #else /* CONFIG_SHRINKER_DEBUG */ 113 #else /* CONFIG_SHRINKER_DEBUG */
>> 114 static inline int shrinker_debugfs_add(struct shrinker *shrinker)
>> 115 {
>> 116 return 0;
>> 117 }
>> 118 static inline struct dentry *shrinker_debugfs_remove(struct shrinker *shrinker)
>> 119 {
>> 120 return NULL;
>> 121 }
154 static inline __printf(2, 3) 122 static inline __printf(2, 3)
155 int shrinker_debugfs_rename(struct shrinker *s 123 int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...)
156 { 124 {
157 return 0; 125 return 0;
158 } 126 }
159 #endif /* CONFIG_SHRINKER_DEBUG */ 127 #endif /* CONFIG_SHRINKER_DEBUG */
160 #endif /* _LINUX_SHRINKER_H */ 128 #endif /* _LINUX_SHRINKER_H */
161 129
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