aboutsummaryrefslogtreecommitdiffstats
path: root/include/linux/bpf.h
blob: 4fb3aa2dc975f26753667d1645d6b2d915f46e05 (plain) (blame)
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
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 */
#ifndef _LINUX_BPF_H
#define _LINUX_BPF_H 1

#include <uapi/linux/bpf.h>

#include <linux/workqueue.h>
#include <linux/file.h>
#include <linux/percpu.h>
#include <linux/err.h>
#include <linux/rbtree_latch.h>
#include <linux/numa.h>
#include <linux/wait.h>
#include <linux/u64_stats_sync.h>

struct bpf_verifier_env;
struct perf_event;
struct bpf_prog;
struct bpf_map;
struct sock;
struct seq_file;
struct btf;
struct btf_type;

/* map is generic key/value storage optionally accesible by eBPF programs */
struct bpf_map_ops {
	/* funcs callable from userspace (via syscall) */
	int (*map_alloc_check)(union bpf_attr *attr);
	struct bpf_map *(*map_alloc)(union bpf_attr *attr);
	void (*map_release)(struct bpf_map *map, struct file *map_file);
	void (*map_free)(struct bpf_map *map);
	int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
	void (*map_release_uref)(struct bpf_map *map);
	void *(*map_lookup_elem_sys_only)(struct bpf_map *map, void *key);

	/* funcs callable from userspace and from eBPF programs */
	void *(*map_lookup_elem)(struct bpf_map *map, void *key);
	int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
	int (*map_delete_elem)(struct bpf_map *map, void *key);
	int (*map_push_elem)(struct bpf_map *map, void *value, u64 flags);
	int (*map_pop_elem)(struct bpf_map *map, void *value);
	int (*map_peek_elem)(struct bpf_map *map, void *value);

	/* funcs called by prog_array and perf_event_array map */
	void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file,
				int fd);
	void (*map_fd_put_ptr)(void *ptr);
	u32 (*map_gen_lookup)(struct bpf_map *map, struct bpf_insn *insn_buf);
	u32 (*map_fd_sys_lookup_elem)(void *ptr);
	void (*map_seq_show_elem)(struct bpf_map *map, void *key,
				  struct seq_file *m);
	int (*map_check_btf)(const struct bpf_map *map,
			     const struct btf *btf,
			     const struct btf_type *key_type,
			     const struct btf_type *value_type);

	/* Direct value access helpers. */
	int (*map_direct_value_addr)(const struct bpf_map *map,
				     u64 *imm, u32 off);
	int (*map_direct_value_meta)(const struct bpf_map *map,
				     u64 imm, u32 *off);
};

struct bpf_map {
	/* The first two cachelines with read-mostly members of which some
	 * are also accessed in fast-path (e.g. ops, max_entries).
	 */
	const struct bpf_map_ops *ops ____cacheline_aligned;
	struct bpf_map *inner_map_meta;
#ifdef CONFIG_SECURITY
	void *security;
#endif
	enum bpf_map_type map_type;
	u32 key_size;
	u32 value_size;
	u32 max_entries;
	u32 map_flags;
	int spin_lock_off; /* >=0 valid offset, <0 error */
	u32 id;
	int numa_node;
	u32 btf_key_type_id;
	u32 btf_value_type_id;
	struct btf *btf;
	u32 pages;
	bool unpriv_array;
	bool frozen; /* write-once */
	/* 48 bytes hole */

	/* The 3rd and 4th cacheline with misc members to avoid false sharing
	 * particularly with refcounting.
	 */
	struct user_struct *user ____cacheline_aligned;
	atomic_t refcnt;
	atomic_t usercnt;
	struct work_struct work;
	char name[BPF_OBJ_NAME_LEN];
};

static inline bool map_value_has_spin_lock(const struct bpf_map *map)
{
	return map->spin_lock_off >= 0;
}

static inline void check_and_init_map_lock(struct bpf_map *map, void *dst)
{
	if (likely(!map_value_has_spin_lock(map)))
		return;
	*(struct bpf_spin_lock *)(dst + map->spin_lock_off) =
		(struct bpf_spin_lock){};
}

/* copy everything but bpf_spin_lock */
static inline void copy_map_value(struct bpf_map *map, void *dst, void *src)
{
	if (unlikely(map_value_has_spin_lock(map))) {
		u32 off = map->spin_lock_off;

		memcpy(dst, src, off);
		memcpy(dst + off + sizeof(struct bpf_spin_lock),
		       src + off + sizeof(struct bpf_spin_lock),
		       map->value_size - off - sizeof(struct bpf_spin_lock));
	} else {
		memcpy(dst, src, map->value_size);
	}
}
void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
			   bool lock_src);

struct bpf_offload_dev;
struct bpf_offloaded_map;

struct bpf_map_dev_ops {
	int (*map_get_next_key)(struct bpf_offloaded_map *map,
				void *key, void *next_key);
	int (*map_lookup_elem)(struct bpf_offloaded_map *map,
			       void *key, void *value);
	int (*map_update_elem)(struct bpf_offloaded_map *map,
			       void *key, void *value, u64 flags);
	int (*map_delete_elem)(struct bpf_offloaded_map *map, void *key);
};

struct bpf_offloaded_map {
	struct bpf_map map;
	struct net_device *netdev;
	const struct bpf_map_dev_ops *dev_ops;
	void *dev_priv;
	struct list_head offloads;
};

static inline struct bpf_offloaded_map *map_to_offmap(struct bpf_map *map)
{
	return container_of(map, struct bpf_offloaded_map, map);
}

static inline bool bpf_map_offload_neutral(const struct bpf_map *map)
{
	return map->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY;
}

static inline bool bpf_map_support_seq_show(const struct bpf_map *map)
{
	return map->btf && map->ops->map_seq_show_elem;
}

int map_check_no_btf(const struct bpf_map *map,
		     const struct btf *btf,
		     const struct btf_type *key_type,
		     const struct btf_type *value_type);

extern const struct bpf_map_ops bpf_map_offload_ops;

/* function argument constraints */
enum bpf_arg_type {
	ARG_DONTCARE = 0,	/* unused argument in helper function */

	/* the following constraints used to prototype
	 * bpf_map_lookup/update/delete_elem() functions
	 */
	ARG_CONST_MAP_PTR,	/* const argument used as pointer to bpf_map */
	ARG_PTR_TO_MAP_KEY,	/* pointer to stack used as map key */
	ARG_PTR_TO_MAP_VALUE,	/* pointer to stack used as map value */
	ARG_PTR_TO_UNINIT_MAP_VALUE,	/* pointer to valid memory used to store a map value */
	ARG_PTR_TO_MAP_VALUE_OR_NULL,	/* pointer to stack used as map value or NULL */

	/* the following constraints used to prototype bpf_memcmp() and other
	 * functions that access data on eBPF program stack
	 */
	ARG_PTR_TO_MEM,		/* pointer to valid memory (stack, packet, map value) */
	ARG_PTR_TO_MEM_OR_NULL, /* pointer to valid memory or NULL */
	ARG_PTR_TO_UNINIT_MEM,	/* pointer to memory does not need to be initialized,
				 * helper function must fill all bytes or clear
				 * them in error case.
				 */

	ARG_CONST_SIZE,		/* number of bytes accessed from memory */
	ARG_CONST_SIZE_OR_ZERO,	/* number of bytes accessed from memory or 0 */

	ARG_PTR_TO_CTX,		/* pointer to context */
	ARG_ANYTHING,		/* any (initialized) argument is ok */
	ARG_PTR_TO_SPIN_LOCK,	/* pointer to bpf_spin_lock */
	ARG_PTR_TO_SOCK_COMMON,	/* pointer to sock_common */
	ARG_PTR_TO_INT,		/* pointer to int */
	ARG_PTR_TO_LONG,	/* pointer to long */
	ARG_PTR_TO_SOCKET,	/* pointer to bpf_sock (fullsock) */
};

/* type of values returned from helper functions */
enum bpf_return_type {
	RET_INTEGER,			/* function returns integer */
	RET_VOID,			/* function doesn't return anything */
	RET_PTR_TO_MAP_VALUE,		/* returns a pointer to map elem value */
	RET_PTR_TO_MAP_VALUE_OR_NULL,	/* returns a pointer to map elem value or NULL */
	RET_PTR_TO_SOCKET_OR_NULL,	/* returns a pointer to a socket or NULL */
	RET_PTR_TO_TCP_SOCK_OR_NULL,	/* returns a pointer to a tcp_sock or NULL */
	RET_PTR_TO_SOCK_COMMON_OR_NULL,	/* returns a pointer to a sock_common or NULL */
};

/* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
 * to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
 * instructions after verifying
 */
struct bpf_func_proto {
	u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
	bool gpl_only;
	bool pkt_access;
	enum bpf_return_type ret_type;
	enum bpf_arg_type arg1_type;
	enum bpf_arg_type arg2_type;
	enum bpf_arg_type arg3_type;
	enum bpf_arg_type arg4_type;
	enum bpf_arg_type arg5_type;
};

/* bpf_context is intentionally undefined structure. Pointer to bpf_context is
 * the first argument to eBPF programs.
 * For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
 */
struct bpf_context;

enum bpf_access_type {
	BPF_READ = 1,
	BPF_WRITE = 2
};

/* types of values stored in eBPF registers */
/* Pointer types represent:
 * pointer
 * pointer + imm
 * pointer + (u16) var
 * pointer + (u16) var + imm
 * if (range > 0) then [ptr, ptr + range - off) is safe to access
 * if (id > 0) means that some 'var' was added
 * if (off > 0) means that 'imm' was added
 */
enum bpf_reg_type {
	NOT_INIT = 0,		 /* nothing was written into register */
	SCALAR_VALUE,		 /* reg doesn't contain a valid pointer */
	PTR_TO_CTX,		 /* reg points to bpf_context */
	CONST_PTR_TO_MAP,	 /* reg points to struct bpf_map */
	PTR_TO_MAP_VALUE,	 /* reg points to map element value */
	PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */
	PTR_TO_STACK,		 /* reg == frame_pointer + offset */
	PTR_TO_PACKET_META,	 /* skb->data - meta_len */
	PTR_TO_PACKET,		 /* reg points to skb->data */
	PTR_TO_PACKET_END,	 /* skb->data + headlen */
	PTR_TO_FLOW_KEYS,	 /* reg points to bpf_flow_keys */
	PTR_TO_SOCKET,		 /* reg points to struct bpf_sock */
	PTR_TO_SOCKET_OR_NULL,	 /* reg points to struct bpf_sock or NULL */
	PTR_TO_SOCK_COMMON,	 /* reg points to sock_common */
	PTR_TO_SOCK_COMMON_OR_NULL, /* reg points to sock_common or NULL */
	PTR_TO_TCP_SOCK,	 /* reg points to struct tcp_sock */
	PTR_TO_TCP_SOCK_OR_NULL, /* reg points to struct tcp_sock or NULL */
	PTR_TO_TP_BUFFER,	 /* reg points to a writable raw tp's buffer */
};

/* The information passed from prog-specific *_is_valid_access
 * back to the verifier.
 */
struct bpf_insn_access_aux {
	enum bpf_reg_type reg_type;
	int ctx_field_size;
};

static inline void
bpf_ctx_record_field_size(struct bpf_insn_access_aux *aux, u32 size)
{
	aux->ctx_field_size = size;
}

struct bpf_prog_ops {
	int (*test_run)(struct bpf_prog *prog, const union bpf_attr *kattr,
			union bpf_attr __user *uattr);
};

struct bpf_verifier_ops {
	/* return eBPF function prototype for verification */
	const struct bpf_func_proto *
	(*get_func_proto)(enum bpf_func_id func_id,
			  const struct bpf_prog *prog);

	/* return true if 'size' wide access at offset 'off' within bpf_context
	 * with 'type' (read or write) is allowed
	 */
	bool (*is_valid_access)(int off, int size, enum bpf_access_type type,
				const struct bpf_prog *prog,
				struct bpf_insn_access_aux *info);
	int (*gen_prologue)(struct bpf_insn *insn, bool direct_write,
			    const struct bpf_prog *prog);
	int (*gen_ld_abs)(const struct bpf_insn *orig,
			  struct bpf_insn *insn_buf);
	u32 (*convert_ctx_access)(enum bpf_access_type type,
				  const struct bpf_insn *src,
				  struct bpf_insn *dst,
				  struct bpf_prog *prog, u32 *target_size);
};

struct bpf_prog_offload_ops {
	/* verifier basic callbacks */
	int (*insn_hook)(struct bpf_verifier_env *env,
			 int insn_idx, int prev_insn_idx);
	int (*finalize)(struct bpf_verifier_env *env);
	/* verifier optimization callbacks (called after .finalize) */
	int (*replace_insn)(struct bpf_verifier_env *env, u32 off,
			    struct bpf_insn *insn);
	int (*remove_insns)(struct bpf_verifier_env *env, u32 off, u32 cnt);
	/* program management callbacks */
	int (*prepare)(struct bpf_prog *prog);
	int (*translate)(struct bpf_prog *prog);
	void (*destroy)(struct bpf_prog *prog);
};

struct bpf_prog_offload {
	struct bpf_prog		*prog;
	struct net_device	*netdev;
	struct bpf_offload_dev	*offdev;
	void			*dev_priv;
	struct list_head	offloads;
	bool			dev_state;
	bool			opt_failed;
	void			*jited_image;
	u32			jited_len;
};

enum bpf_cgroup_storage_type {
	BPF_CGROUP_STORAGE_SHARED,
	BPF_CGROUP_STORAGE_PERCPU,
	__BPF_CGROUP_STORAGE_MAX
};

#define MAX_BPF_CGROUP_STORAGE_TYPE __BPF_CGROUP_STORAGE_MAX

struct bpf_prog_stats {
	u64 cnt;
	u64 nsecs;
	struct u64_stats_sync syncp;
};

struct bpf_prog_aux {
	atomic_t refcnt;
	u32 used_map_cnt;
	u32 max_ctx_offset;
	u32 max_pkt_offset;
	u32 max_tp_access;
	u32 stack_depth;
	u32 id;
	u32 func_cnt; /* used by non-func prog as the number of func progs */
	u32 func_idx; /* 0 for non-func prog, the index in func array for func prog */
	bool offload_requested;
	struct bpf_prog **func;
	void *jit_data; /* JIT specific data. arch dependent */
	struct latch_tree_node ksym_tnode;
	struct list_head ksym_lnode;
	const struct bpf_prog_ops *ops;
	struct bpf_map **used_maps;
	struct bpf_prog *prog;
	struct user_struct *user;
	u64 load_time; /* ns since boottime */
	struct bpf_map *cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE];
	char name[BPF_OBJ_NAME_LEN];
#ifdef CONFIG_SECURITY
	void *security;
#endif
	struct bpf_prog_offload *offload;
	struct btf *btf;
	struct bpf_func_info *func_info;
	/* bpf_line_info loaded from userspace.  linfo->insn_off
	 * has the xlated insn offset.
	 * Both the main and sub prog share the same linfo.
	 * The subprog can access its first linfo by
	 * using the linfo_idx.
	 */
	struct bpf_line_info *linfo;
	/* jited_linfo is the jited addr of the linfo.  It has a
	 * one to one mapping to linfo:
	 * jited_linfo[i] is the jited addr for the linfo[i]->insn_off.
	 * Both the main and sub prog share the same jited_linfo.
	 * The subprog can access its first jited_linfo by
	 * using the linfo_idx.
	 */
	void **jited_linfo;
	u32 func_info_cnt;
	u32 nr_linfo;
	/* subprog can use linfo_idx to access its first linfo and
	 * jited_linfo.
	 * main prog always has linfo_idx == 0
	 */
	u32 linfo_idx;
	struct bpf_prog_stats __percpu *stats;
	union {
		struct work_struct work;
		struct rcu_head	rcu;
	};
};

struct bpf_array {
	struct bpf_map map;
	u32 elem_size;
	u32 index_mask;
	/* 'ownership' of prog_array is claimed by the first program that
	 * is going to use this map or by the first program which FD is stored
	 * in the map to make sure that all callers and callees have the same
	 * prog_type and JITed flag
	 */
	enum bpf_prog_type owner_prog_type;
	bool owner_jited;
	union {
		char value[0] __aligned(8);
		void *ptrs[0] __aligned(8);
		void __percpu *pptrs[0] __aligned(8);
	};
};

#define BPF_COMPLEXITY_LIMIT_INSNS      1000000 /* yes. 1M insns */
#define MAX_TAIL_CALL_CNT 32

#define BPF_F_ACCESS_MASK	(BPF_F_RDONLY |		\
				 BPF_F_RDONLY_PROG |	\
				 BPF_F_WRONLY |		\
				 BPF_F_WRONLY_PROG)

#define BPF_MAP_CAN_READ	BIT(0)
#define BPF_MAP_CAN_WRITE	BIT(1)

static inline u32 bpf_map_flags_to_cap(struct bpf_map *map)
{
	u32 access_flags = map->map_flags & (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG);

	/* Combination of BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG is
	 * not possible.
	 */
	if (access_flags & BPF_F_RDONLY_PROG)
		return BPF_MAP_CAN_READ;
	else if (access_flags & BPF_F_WRONLY_PROG)
		return BPF_MAP_CAN_WRITE;
	else
		return BPF_MAP_CAN_READ | BPF_MAP_CAN_WRITE;
}

static inline bool bpf_map_flags_access_ok(u32 access_flags)
{
	return (access_flags & (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG)) !=
	       (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG);
}

struct bpf_event_entry {
	struct perf_event *event;
	struct file *perf_file;
	struct file *map_file;
	struct rcu_head rcu;
};

bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
int bpf_prog_calc_tag(struct bpf_prog *fp);

const struct bpf_func_proto *bpf_get_trace_printk_proto(void);

typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
					unsigned long off, unsigned long len);
typedef u32 (*bpf_convert_ctx_access_t)(enum bpf_access_type type,
					const struct bpf_insn *src,
					struct bpf_insn *dst,
					struct bpf_prog *prog,
					u32 *target_size);

u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
		     void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);

/* an array of programs to be executed under rcu_lock.
 *
 * Typical usage:
 * ret = BPF_PROG_RUN_ARRAY(&bpf_prog_array, ctx, BPF_PROG_RUN);
 *
 * the structure returned by bpf_prog_array_alloc() should be populated
 * with program pointers and the last pointer must be NULL.
 * The user has to keep refcnt on the program and make sure the program
 * is removed from the array before bpf_prog_put().
 * The 'struct bpf_prog_array *' should only be replaced with xchg()
 * since other cpus are walking the array of pointers in parallel.
 */
struct bpf_prog_array_item {
	struct bpf_prog *prog;
	struct bpf_cgroup_storage *cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE];
};

struct bpf_prog_array {
	struct rcu_head rcu;
	struct bpf_prog_array_item items[0];
};

struct bpf_prog_array *bpf_prog_array_alloc(u32 prog_cnt, gfp_t flags);
void bpf_prog_array_free(struct bpf_prog_array __rcu *progs);
int bpf_prog_array_length(struct bpf_prog_array __rcu *progs);
int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs,
				__u32 __user *prog_ids, u32 cnt);

void bpf_prog_array_delete_safe(struct bpf_prog_array __rcu *progs,
				struct bpf_prog *old_prog);
int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array,
			     u32 *prog_ids, u32 request_cnt,
			     u32 *prog_cnt);
int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
			struct bpf_prog *exclude_prog,
			struct bpf_prog *include_prog,
			struct bpf_prog_array **new_array);

#define __BPF_PROG_RUN_ARRAY(array, ctx, func, check_non_null)	\
	({						\
		struct bpf_prog_array_item *_item;	\
		struct bpf_prog *_prog;			\
		struct bpf_prog_array *_array;		\
		u32 _ret = 1;				\
		preempt_disable();			\
		rcu_read_lock();			\
		_array = rcu_dereference(array);	\
		if (unlikely(check_non_null && !_array))\
			goto _out;			\
		_item = &_array->items[0];		\
		while ((_prog = READ_ONCE(_item->prog))) {		\
			bpf_cgroup_storage_set(_item->cgroup_storage);	\
			_ret &= func(_prog, ctx);	\
			_item++;			\
		}					\
_out:							\
		rcu_read_unlock();			\
		preempt_enable();			\
		_ret;					\
	 })

#define BPF_PROG_RUN_ARRAY(array, ctx, func)		\
	__BPF_PROG_RUN_ARRAY(array, ctx, func, false)

#define BPF_PROG_RUN_ARRAY_CHECK(array, ctx, func)	\
	__BPF_PROG_RUN_ARRAY(array, ctx, func, true)

#ifdef CONFIG_BPF_SYSCALL
DECLARE_PER_CPU(int, bpf_prog_active);

extern const struct file_operations bpf_map_fops;
extern const struct file_operations bpf_prog_fops;

#define BPF_PROG_TYPE(_id, _name) \
	extern const struct bpf_prog_ops _name ## _prog_ops; \
	extern const struct bpf_verifier_ops _name ## _verifier_ops;
#define BPF_MAP_TYPE(_id, _ops) \
	extern const struct bpf_map_ops _ops;
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE

extern const struct bpf_prog_ops bpf_offload_prog_ops;
extern const struct bpf_verifier_ops tc_cls_act_analyzer_ops;
extern const struct bpf_verifier_ops xdp_analyzer_ops;

struct bpf_prog *bpf_prog_get(u32 ufd);
struct bpf_prog *bpf_prog_get_type_dev(u32 ufd, enum bpf_prog_type type,
				       bool attach_drv);
struct bpf_prog * __must_check bpf_prog_add(struct bpf_prog *prog, int i);
void bpf_prog_sub(struct bpf_prog *prog, int i);
struct bpf_prog * __must_check bpf_prog_inc(struct bpf_prog *prog);
struct bpf_prog * __must_check bpf_prog_inc_not_zero(struct bpf_prog *prog);
void bpf_prog_put(struct bpf_prog *prog);
int __bpf_prog_charge(struct user_struct *user, u32 pages);
void __bpf_prog_uncharge(struct user_struct *user, u32 pages);

void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock);
void bpf_map_free_id(struct bpf_map *map, bool do_idr_lock);

struct bpf_map *bpf_map_get_with_uref(u32 ufd);
struct bpf_map *__bpf_map_get(struct fd f);
struct bpf_map * __must_check bpf_map_inc(struct bpf_map *map, bool uref);
void bpf_map_put_with_uref(struct bpf_map *map);
void bpf_map_put(struct bpf_map *map);
int bpf_map_precharge_memlock(u32 pages);
int bpf_map_charge_memlock(struct bpf_map *map, u32 pages);
void bpf_map_uncharge_memlock(struct bpf_map *map, u32 pages);
void *bpf_map_area_alloc(size_t size, int numa_node);
void bpf_map_area_free(void *base);
void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr);

extern int sysctl_unprivileged_bpf_disabled;
extern int sysctl_bpf_stats_enabled;

int bpf_map_new_fd(struct bpf_map *map, int flags);
int bpf_prog_new_fd(struct bpf_prog *prog);

int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
int bpf_obj_get_user(const char __user *pathname, int flags);

int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
			   u64 flags);
int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
			    u64 flags);

int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value);

int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
				 void *key, void *value, u64 map_flags);
int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);
int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
				void *key, void *value, u64 map_flags);
int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);

int bpf_get_file_flag(int flags);
int bpf_check_uarg_tail_zero(void __user *uaddr, size_t expected_size,
			     size_t actual_size);

/* memcpy that is used with 8-byte aligned pointers, power-of-8 size and
 * forced to use 'long' read/writes to try to atomically copy long counters.
 * Best-effort only.  No barriers here, since it _will_ race with concurrent
 * updates from BPF programs. Called from bpf syscall and mostly used with
 * size 8 or 16 bytes, so ask compiler to inline it.
 */
static inline void bpf_long_memcpy(void *dst, const void *src, u32 size)
{
	const long *lsrc = src;
	long *ldst = dst;

	size /= sizeof(long);
	while (size--)
		*ldst++ = *lsrc++;
}

/* verify correctness of eBPF program */
int bpf_check(struct bpf_prog **fp, union bpf_attr *attr,
	      union bpf_attr __user *uattr);
void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth);

/* Map specifics */
struct xdp_buff;
struct sk_buff;

struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
void __dev_map_insert_ctx(struct bpf_map *map, u32 index);
void __dev_map_flush(struct bpf_map *map);
int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
		    struct net_device *dev_rx);
int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
			     struct bpf_prog *xdp_prog);

struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key);
void __cpu_map_insert_ctx(struct bpf_map *map, u32 index);
void __cpu_map_flush(struct bpf_map *map);
int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
		    struct net_device *dev_rx);

/* Return map's numa specified by userspace */
static inline int bpf_map_attr_numa_node(const union bpf_attr *attr)
{
	return (attr->map_flags & BPF_F_NUMA_NODE) ?
		attr->numa_node : NUMA_NO_NODE;
}

struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type);
int array_map_alloc_check(union bpf_attr *attr);

int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
			  union bpf_attr __user *uattr);
int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
			  union bpf_attr __user *uattr);
int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
				     const union bpf_attr *kattr,
				     union bpf_attr __user *uattr);
#else /* !CONFIG_BPF_SYSCALL */
static inline struct bpf_prog *bpf_prog_get(u32 ufd)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline struct bpf_prog *bpf_prog_get_type_dev(u32 ufd,
						     enum bpf_prog_type type,
						     bool attach_drv)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline struct bpf_prog * __must_check bpf_prog_add(struct bpf_prog *prog,
							  int i)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline void bpf_prog_sub(struct bpf_prog *prog, int i)
{
}

static inline void bpf_prog_put(struct bpf_prog *prog)
{
}

static inline struct bpf_prog * __must_check bpf_prog_inc(struct bpf_prog *prog)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline struct bpf_prog *__must_check
bpf_prog_inc_not_zero(struct bpf_prog *prog)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline int __bpf_prog_charge(struct user_struct *user, u32 pages)
{
	return 0;
}

static inline void __bpf_prog_uncharge(struct user_struct *user, u32 pages)
{
}

static inline int bpf_obj_get_user(const char __user *pathname, int flags)
{
	return -EOPNOTSUPP;
}

static inline struct net_device  *__dev_map_lookup_elem(struct bpf_map *map,
						       u32 key)
{
	return NULL;
}

static inline void __dev_map_insert_ctx(struct bpf_map *map, u32 index)
{
}

static inline void __dev_map_flush(struct bpf_map *map)
{
}

struct xdp_buff;
struct bpf_dtab_netdev;

static inline
int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
		    struct net_device *dev_rx)
{
	return 0;
}

struct sk_buff;

static inline int dev_map_generic_redirect(struct bpf_dtab_netdev *dst,
					   struct sk_buff *skb,
					   struct bpf_prog *xdp_prog)
{
	return 0;
}

static inline
struct bpf_cpu_map_entry *__cpu_map_lookup_elem(struct bpf_map *map, u32 key)
{
	return NULL;
}

static inline void __cpu_map_insert_ctx(struct bpf_map *map, u32 index)
{
}

static inline void __cpu_map_flush(struct bpf_map *map)
{
}

static inline int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu,
				  struct xdp_buff *xdp,
				  struct net_device *dev_rx)
{
	return 0;
}

static inline struct bpf_prog *bpf_prog_get_type_path(const char *name,
				enum bpf_prog_type type)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline int bpf_prog_test_run_xdp(struct bpf_prog *prog,
					const union bpf_attr *kattr,
					union bpf_attr __user *uattr)
{
	return -ENOTSUPP;
}

static inline int bpf_prog_test_run_skb(struct bpf_prog *prog,
					const union bpf_attr *kattr,
					union bpf_attr __user *uattr)
{
	return -ENOTSUPP;
}

static inline int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
						   const union bpf_attr *kattr,
						   union bpf_attr __user *uattr)
{
	return -ENOTSUPP;
}
#endif /* CONFIG_BPF_SYSCALL */

static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
						 enum bpf_prog_type type)
{
	return bpf_prog_get_type_dev(ufd, type, false);
}

bool bpf_prog_get_ok(struct bpf_prog *, enum bpf_prog_type *, bool);

int bpf_prog_offload_compile(struct bpf_prog *prog);
void bpf_prog_offload_destroy(struct bpf_prog *prog);
int bpf_prog_offload_info_fill(struct bpf_prog_info *info,
			       struct bpf_prog *prog);

int bpf_map_offload_info_fill(struct bpf_map_info *info, struct bpf_map *map);

int bpf_map_offload_lookup_elem(struct bpf_map *map, void *key, void *value);
int bpf_map_offload_update_elem(struct bpf_map *map,
				void *key, void *value, u64 flags);
int bpf_map_offload_delete_elem(struct bpf_map *map, void *key);
int bpf_map_offload_get_next_key(struct bpf_map *map,
				 void *key, void *next_key);

bool bpf_offload_prog_map_match(struct bpf_prog *prog, struct bpf_map *map);

struct bpf_offload_dev *
bpf_offload_dev_create(const struct bpf_prog_offload_ops *ops, void *priv);
void bpf_offload_dev_destroy(struct bpf_offload_dev *offdev);
void *bpf_offload_dev_priv(struct bpf_offload_dev *offdev);
int bpf_offload_dev_netdev_register(struct bpf_offload_dev *offdev,
				    struct net_device *netdev);
void bpf_offload_dev_netdev_unregister(struct bpf_offload_dev *offdev,
				       struct net_device *netdev);
bool bpf_offload_dev_match(struct bpf_prog *prog, struct net_device *netdev);

#if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL)
int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr);

static inline bool bpf_prog_is_dev_bound(const struct bpf_prog_aux *aux)
{
	return aux->offload_requested;
}

static inline bool bpf_map_is_dev_bound(struct bpf_map *map)
{
	return unlikely(map->ops == &bpf_map_offload_ops);
}

struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr);
void bpf_map_offload_map_free(struct bpf_map *map);
#else
static inline int bpf_prog_offload_init(struct bpf_prog *prog,
					union bpf_attr *attr)
{
	return -EOPNOTSUPP;
}

static inline bool bpf_prog_is_dev_bound(struct bpf_prog_aux *aux)
{
	return false;
}

static inline bool bpf_map_is_dev_bound(struct bpf_map *map)
{
	return false;
}

static inline struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr)
{
	return ERR_PTR(-EOPNOTSUPP);
}

static inline void bpf_map_offload_map_free(struct bpf_map *map)
{
}
#endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */

#if defined(CONFIG_BPF_STREAM_PARSER)
int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog, u32 which);
int sock_map_get_from_fd(const union bpf_attr *attr, struct bpf_prog *prog);
#else
static inline int sock_map_prog_update(struct bpf_map *map,
				       struct bpf_prog *prog, u32 which)
{
	return -EOPNOTSUPP;
}

static inline int sock_map_get_from_fd(const union bpf_attr *attr,
				       struct bpf_prog *prog)
{
	return -EINVAL;
}
#endif

#if defined(CONFIG_XDP_SOCKETS)
struct xdp_sock;
struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map, u32 key);
int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
		       struct xdp_sock *xs);
void __xsk_map_flush(struct bpf_map *map);
#else
struct xdp_sock;
static inline struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map,
						     u32 key)
{
	return NULL;
}

static inline int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,
				     struct xdp_sock *xs)
{
	return -EOPNOTSUPP;
}

static inline void __xsk_map_flush(struct bpf_map *map)
{
}
#endif

#if defined(CONFIG_INET) && defined(CONFIG_BPF_SYSCALL)
void bpf_sk_reuseport_detach(struct sock *sk);
int bpf_fd_reuseport_array_lookup_elem(struct bpf_map *map, void *key,
				       void *value);
int bpf_fd_reuseport_array_update_elem(struct bpf_map *map, void *key,
				       void *value, u64 map_flags);
#else
static inline void bpf_sk_reuseport_detach(struct sock *sk)
{
}

#ifdef CONFIG_BPF_SYSCALL
static inline int bpf_fd_reuseport_array_lookup_elem(struct bpf_map *map,
						     void *key, void *value)
{
	return -EOPNOTSUPP;
}

static inline int bpf_fd_reuseport_array_update_elem(struct bpf_map *map,
						     void *key, void *value,
						     u64 map_flags)
{
	return -EOPNOTSUPP;
}
#endif /* CONFIG_BPF_SYSCALL */
#endif /* defined(CONFIG_INET) && defined(CONFIG_BPF_SYSCALL) */

/* verifier prototypes for helper functions called from eBPF programs */
extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
extern const struct bpf_func_proto bpf_map_update_elem_proto;
extern const struct bpf_func_proto bpf_map_delete_elem_proto;
extern const struct bpf_func_proto bpf_map_push_elem_proto;
extern const struct bpf_func_proto bpf_map_pop_elem_proto;
extern const struct bpf_func_proto bpf_map_peek_elem_proto;

extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
extern const struct bpf_func_proto bpf_get_numa_node_id_proto;
extern const struct bpf_func_proto bpf_tail_call_proto;
extern const struct bpf_func_proto bpf_ktime_get_ns_proto;
extern const struct bpf_func_proto bpf_get_current_pid_tgid_proto;
extern const struct bpf_func_proto bpf_get_current_uid_gid_proto;
extern const struct bpf_func_proto bpf_get_current_comm_proto;
extern const struct bpf_func_proto bpf_get_stackid_proto;
extern const struct bpf_func_proto bpf_get_stack_proto;
extern const struct bpf_func_proto bpf_sock_map_update_proto;
extern const struct bpf_func_proto bpf_sock_hash_update_proto;
extern const struct bpf_func_proto bpf_get_current_cgroup_id_proto;
extern const struct bpf_func_proto bpf_msg_redirect_hash_proto;
extern const struct bpf_func_proto bpf_msg_redirect_map_proto;
extern const struct bpf_func_proto bpf_sk_redirect_hash_proto;
extern const struct bpf_func_proto bpf_sk_redirect_map_proto;
extern const struct bpf_func_proto bpf_spin_lock_proto;
extern const struct bpf_func_proto bpf_spin_unlock_proto;
extern const struct bpf_func_proto bpf_get_local_storage_proto;
extern const struct bpf_func_proto bpf_strtol_proto;
extern const struct bpf_func_proto bpf_strtoul_proto;

/* Shared helpers among cBPF and eBPF. */
void bpf_user_rnd_init_once(void);
u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);

#if defined(CONFIG_NET)
bool bpf_sock_common_is_valid_access(int off, int size,
				     enum bpf_access_type type,
				     struct bpf_insn_access_aux *info);
bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type,
			      struct bpf_insn_access_aux *info);
u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
				const struct bpf_insn *si,
				struct bpf_insn *insn_buf,
				struct bpf_prog *prog,
				u32 *target_size);
#else
static inline bool bpf_sock_common_is_valid_access(int off, int size,
						   enum bpf_access_type type,
						   struct bpf_insn_access_aux *info)
{
	return false;
}
static inline bool bpf_sock_is_valid_access(int off, int size,
					    enum bpf_access_type type,
					    struct bpf_insn_access_aux *info)
{
	return false;
}
static inline u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
					      const struct bpf_insn *si,
					      struct bpf_insn *insn_buf,
					      struct bpf_prog *prog,
					      u32 *target_size)
{
	return 0;
}
#endif

#ifdef CONFIG_INET
bool bpf_tcp_sock_is_valid_access(int off, int size, enum bpf_access_type type,
				  struct bpf_insn_access_aux *info);

u32 bpf_tcp_sock_convert_ctx_access(enum bpf_access_type type,
				    const struct bpf_insn *si,
				    struct bpf_insn *insn_buf,
				    struct bpf_prog *prog,
				    u32 *target_size);
#else
static inline bool bpf_tcp_sock_is_valid_access(int off, int size,
						enum bpf_access_type type,
						struct bpf_insn_access_aux *info)
{
	return false;
}

static inline u32 bpf_tcp_sock_convert_ctx_access(enum bpf_access_type type,
						  const struct bpf_insn *si,
						  struct bpf_insn *insn_buf,
						  struct bpf_prog *prog,
						  u32 *target_size)
{
	return 0;
}
#endif /* CONFIG_INET */

#endif /* _LINUX_BPF_H */
='sha1'>f8891e5e1f93
1da177e4c3f4
3bb1a852ab6c

1da177e4c3f4




f7b7fd8f3ebb



f1a9ee758de7
1da177e4c3f4

d6277db4ab27





1da177e4c3f4
d6277db4ab27

1da177e4c3f4
e815af95f949

d6277db4ab27
1da177e4c3f4
d6277db4ab27


e1dbeda60a7e
1da177e4c3f4
1da177e4c3f4
e1dbeda60a7e


1da177e4c3f4


c878538598d1

1da177e4c3f4












b15e0905f2b9
1da177e4c3f4
f3fe65122da0
1da177e4c3f4

e815af95f949

1da177e4c3f4

d6277db4ab27


3bb1a852ab6c
1da177e4c3f4
3bb1a852ab6c
32a4330d4156






1da177e4c3f4
b15e0905f2b9

05ff51376f01
1da177e4c3f4
e815af95f949
1da177e4c3f4
b15e0905f2b9
c878538598d1

e815af95f949

1da177e4c3f4





05ff51376f01
1da177e4c3f4

1da177e4c3f4





f1a9ee758de7

3fcfab16c5b8
1da177e4c3f4






d6277db4ab27
1da177e4c3f4


3bb1a852ab6c




1da177e4c3f4


3bb1a852ab6c
1da177e4c3f4


8357376d3df2


1da177e4c3f4


05ff51376f01
1da177e4c3f4

























1da177e4c3f4
















930d915252ed
831441862956
1da177e4c3f4



3e1d1d28d99d
1da177e4c3f4









b1296cc48b39


1da177e4c3f4



b1296cc48b39





1da177e4c3f4










f3fe65122da0
1da177e4c3f4


7fb1d9fca5c6
1da177e4c3f4


02a0e53d8227
1da177e4c3f4
8d0986e289a4
1da177e4c3f4
8d0986e289a4
1da177e4c3f4



d6277db4ab27





e07aa05b606d

d6277db4ab27








e815af95f949
d6277db4ab27



c878538598d1

d6277db4ab27

c878538598d1

bbdb396a60b2
d6277db4ab27


c878538598d1

d6277db4ab27

c878538598d1

d6277db4ab27








76395d37611e

c878538598d1
76395d37611e

d6277db4ab27






1da177e4c3f4
69e05944af39
1da177e4c3f4
d6277db4ab27
69e05944af39
d6277db4ab27

d6277db4ab27





66e1707bc346
1da177e4c3f4


69e05944af39
76395d37611e
972d1a7b1405
d6277db4ab27




1da177e4c3f4
d6277db4ab27





1da177e4c3f4
d6277db4ab27











d6277db4ab27








d6277db4ab27
d6277db4ab27




76395d37611e

d6277db4ab27




3fcfab16c5b8
d6277db4ab27
248a0301e703
d6277db4ab27




76395d37611e
d6277db4ab27

76395d37611e
d6277db4ab27

76395d37611e
d6277db4ab27

1da177e4c3f4
d6277db4ab27
1da177e4c3f4



1da177e4c3f4



9c7b216d23e8
69e05944af39
1da177e4c3f4


58c0a4a7864b
1da177e4c3f4
8bb7844286fb
58c0a4a7864b

1da177e4c3f4







1da177e4c3f4
3218ae14b1e3





















1da177e4c3f4

3218ae14b1e3
69e05944af39
1da177e4c3f4
9422ffba4adc
3218ae14b1e3
1da177e4c3f4




9eeff2395e3c






9eeff2395e3c


1b2ffb7896ad




9eeff2395e3c
a92f71263af9





9eeff2395e3c
9614634fe6a1





0ff38490c836





9eeff2395e3c

179e96395b1f
9eeff2395e3c
7fb2d46d396b
69e05944af39
9eeff2395e3c

8695949a1d7c
05ff51376f01
179e96395b1f


69e05944af39

179e96395b1f
d6277db4ab27
66e1707bc346
179e96395b1f
83e33a471176
9eeff2395e3c

9eeff2395e3c
d4f7796e9b38





9eeff2395e3c

c84db23c6e58
0ff38490c836








3bb1a852ab6c
0ff38490c836



c84db23c6e58
83e33a471176

2a16e3f4b0c4
7fb2d46d396b
0ff38490c836



2a16e3f4b0c4
0ff38490c836

2a16e3f4b0c4
0ff38490c836
83e33a471176

0ff38490c836
83e33a471176






2a16e3f4b0c4

9eeff2395e3c
d4f7796e9b38
05ff51376f01
9eeff2395e3c
179e96395b1f


179e96395b1f
d773ed6b856a
179e96395b1f

0ff38490c836

34aa1330f9b3
9614634fe6a1




179e96395b1f
34aa1330f9b3
0ff38490c836


9614634fe6a1
179e96395b1f
d773ed6b856a


179e96395b1f
d773ed6b856a
179e96395b1f
d773ed6b856a
179e96395b1f







89fa30242fac
37c0708dbee5
179e96395b1f
d773ed6b856a






179e96395b1f
9eeff2395e3c
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
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034




















                                                                     
                         













                                                                  
                        
                          
                          
                             





                          

                     
                     


                                                                           
                                     
                       


                          


                                                      




                                                                 

                       

                              

                  
 






                                                                       







                                                                               

  

































                                                                         
                                                                             






                                                   
                                                 
 



                                                       
 
                                 



             
                                                   



                                    
 
                                   









                                                                            
                                                                            






                                                                              

                                                      
   

                                                                

                                  
                              




                                                
                                                                              



                                                             
                                                                          

                                                        
                                  

                                             












                                                                           






                                                      
                                      
 

                                                                              

                                             

                                                              
                                                                  







                                                
                   





























                                                                          
                                          























                                                                                

                                                  


                          





                               











                                                                           
  

                                                               
   

                                                                               
























                                                                              
                                        

















                                                                            

                                               







                                                               
                                                    


                                               








                                                                             



                                                                
                                                           





                                    





                                                                            
                                                                    
 

                                              

                                            
          






















                                                                              

























                                                                 
  
                                                           
   
                                                                  

                                                                       



                                  
                                       

















                                              
                                            

                                 



                                                       



                                                                             













                                                                              

                                                  
                                                 
                         
                 
 
                                                                      
                                                                       

                                                                               






                                                              
                                                           
                                                           
                                                     


                                             





                                                                         
                                                        









                                                                  
                                                                               
                                                 

                                                  
                                                 
                         
                                               


                                                                     
                                                                         




                                                     

                                                                             
                                                  
                                 









































                                                                                
                                                               
                                         


                                  
                               










                                                              
                                         



                                                      
                                                
                            

 














                                                                             
                                                   




























                                                                        
  












                                                                   

                                                       


                                                

                                                                
                                                            
 
                                   
                           
 
                                                                       





                                       


                                                          
                                          
 


                                                         
                                   





                                                              
 
















































                                                                             





                        














                                                                          
  

















                                                                      

                                                                               
   

                                                                           


                             
                                     
                                       




                                       
            
                                  


                                       
                                        
 
                                                                  

                                                                   

                                                                             
                                                           
                                                           



                                                                         


                                                 
                                      






















                                                                              
                                         

                                          

                                                                             
                      
                                                                             
                                                                
 


                                  
                                           




                                                       
                                                 
                                         










                                                                      
                                        
                                     
     
                           
                               
                            

 













                                                                                

                                                     

                                                                        

 
















                                                                            
                                                                         
                                                                      
 
                              
                             
                                





                                                                        
 
                           


                                   
                               
 


                                                  



                                                                              
                                                                     






                                                                                

                                                                          
                                                       












                                                                               
                                                                             

                  







































                                                                           



                                                                               
                     

                                           


                                       


                                                                             
                                         
                                                         

                                         






                                                                        
                                                                       












                                                                  
                                         
                                 
                                             

                                      
                                                            
                                                                         

                                                
                                                                          








                                                         
                                                          










                                                                
                                         
                                 
                                             
                                                          
                                                                        

                                                
                                                                        





                                                         
                                                        
 


                                                          
 
                               




                                                                                

                                                                 


                                  
                                 
                                       




                                                                         

                                                                   





                                              

                                                                     





                                                

                                          
                                                   
                                                                             
                                                
                                                                           


                                  
                                                     
                                                                             
                                                  

                                                                              


                 
                                           
                            

















                                                                              
                                                                    
                                                                
 
                                       

              
                                  


                                             
                                          

                                 
                                                                    

                                 
                                                            
 
                                                                                

                                                                

                                          
                                                                
         
                            














                                                                             

                                                                              


                     
                                        
                                       
                                                                     

                                    
 
                                   



                                             
                                                                    

                                 

                                                                     


                                                                  
                                   
                                    

                                             






                                                                         
                                    
                                                                      

                                                          

                                                           










                                                                             

                                                                   
                                                                        
                                              


                                                                     

                                                                       
                                                      
         
                                                                              
                                                             
                        
    








                                                                            
                                            

                                             
                                                                    

                                 
                                               



                   

















                                                                               

                                                                       

                                  
                                     









                                                          
                                                         

                                    
                                                                           






                                                                  



                                                                           
















                                                                               
                                                               
 


                         
                                    
                                   
                                                                     


                                       

                                                     
                               

                                                      
          




                                                                           


                          
                         
                                        
                                   
 

                                                




                                                                      



                                                                  
                                   

                                 





                                                                     
 

                                                  
 

                                                              
                                         
 


                                                                             
                                      
                         
                 


                                 


                                                                  

                                                                             












                                                                               
                                    
 
                                                  

                                         

                                                                 

                                         


                                                                             
                                                    
                                          
                                                                    






                                                                                 
                                                          

                                                                        
                                                                      
                                                       
                                                            
                                         
                                                                  

                                                                          

                                                                              





                                                                          
                                                                            

                                                     





                                                                             

                                                                             
                                                      






                                                                               
                                                     


                              




                                                                                


                                                          
                                                       


                               


                                


                                
                            

























                                                                 
















                                                                        
                                                             
                        



                                        
 









                                                                                


                                               



                                                        





                                                                              










                                                                       
                                  


                                 
                                                                  


                                                
                                                            
                       
                                                   
                       
                                                   



                





                                                                              

                                                                        








                                          
                                                                            



                                                                  

                                                                               

                                                                           

                                                                          
                                                                               


                         

                                                                         

                                                                     

                                                                    








                                                                          

                                          
                                                                             

 






                                                                          
   
                                                       
 
                                         
                              

                                           





                                             
                                                      


                                                
 
                                      
                                                         




                                                                    
                              





                                                        
         











                                                                








                                                                           
                                          




                                                                             

                                                               




                                                                     
                                                                
                 
         




                                                                           
                   

                                                         
                                                                              

                                                                             
         

    
                                      
 



                   



                                                                     
                                                             
                                                                   


                         
                
 
                                                                  

                                                         







                                                                          
 





















                                                                           

                                   
                
 
                     
                                               
                                




                                         






                                                                          


                                    




                                                                   
  





                                                                   
  





                                                                          





                                                                          

                                                            
                                                                                
 
                                                           
                                                  

                                           
                     
                                       


                                                                       

                                                                  
                                     
                                            
                                                      
          
                                       

                             
                       





                                                                            

                                          
 








                                                                     
                                                                    



                                                                         
 

                                                                      
                  
                                                                             



                                                                              
                  

                                                                              
                   
                                                                     

                                                                    
                         






                                                                     

         
                                
                                                        
                                        
 


                                                                       
                    
                

          

                                                               
          




                                                                        
           
                                                  


                                                                             
                         
 


                                            
          
                                                               
           
                                                                       







                                                                          
                                    
                                                                    
                         






                                                              
 
      
/*
 *  linux/mm/vmscan.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  Swap reorganised 29.12.95, Stephen Tweedie.
 *  kswapd added: 7.1.96  sct
 *  Removed kswapd_ctl limits, and swap out as many pages as needed
 *  to bring the system back to freepages.high: 2.4.97, Rik van Riel.
 *  Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
 *  Multiqueue VM started 5.8.00, Rik van Riel.
 */

#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/vmstat.h>
#include <linux/file.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h>	/* for try_to_release_page(),
					buffer_heads_over_limit */
#include <linux/mm_inline.h>
#include <linux/pagevec.h>
#include <linux/backing-dev.h>
#include <linux/rmap.h>
#include <linux/topology.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/notifier.h>
#include <linux/rwsem.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/memcontrol.h>

#include <asm/tlbflush.h>
#include <asm/div64.h>

#include <linux/swapops.h>

#include "internal.h"

struct scan_control {
	/* Incremented by the number of inactive pages that were scanned */
	unsigned long nr_scanned;

	/* This context's GFP mask */
	gfp_t gfp_mask;

	int may_writepage;

	/* Can pages be swapped as part of reclaim? */
	int may_swap;

	/* This context's SWAP_CLUSTER_MAX. If freeing memory for
	 * suspend, we effectively ignore SWAP_CLUSTER_MAX.
	 * In this context, it doesn't matter that we scan the
	 * whole list at once. */
	int swap_cluster_max;

	int swappiness;

	int all_unreclaimable;

	int order;

	/*
	 * Pages that have (or should have) IO pending.  If we run into
	 * a lot of these, we're better off waiting a little for IO to
	 * finish rather than scanning more pages in the VM.
	 */
	int nr_io_pages;

	/* Which cgroup do we reclaim from */
	struct mem_cgroup *mem_cgroup;

	/* Pluggable isolate pages callback */
	unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst,
			unsigned long *scanned, int order, int mode,
			struct zone *z, struct mem_cgroup *mem_cont,
			int active);
};

#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))

#ifdef ARCH_HAS_PREFETCH
#define prefetch_prev_lru_page(_page, _base, _field)			\
	do {								\
		if ((_page)->lru.prev != _base) {			\
			struct page *prev;				\
									\
			prev = lru_to_page(&(_page->lru));		\
			prefetch(&prev->_field);			\
		}							\
	} while (0)
#else
#define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
#endif

#ifdef ARCH_HAS_PREFETCHW
#define prefetchw_prev_lru_page(_page, _base, _field)			\
	do {								\
		if ((_page)->lru.prev != _base) {			\
			struct page *prev;				\
									\
			prev = lru_to_page(&(_page->lru));		\
			prefetchw(&prev->_field);			\
		}							\
	} while (0)
#else
#define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
#endif

/*
 * From 0 .. 100.  Higher means more swappy.
 */
int vm_swappiness = 60;
long vm_total_pages;	/* The total number of pages which the VM controls */

static LIST_HEAD(shrinker_list);
static DECLARE_RWSEM(shrinker_rwsem);

/*
 * Add a shrinker callback to be called from the vm
 */
void register_shrinker(struct shrinker *shrinker)
{
	shrinker->nr = 0;
	down_write(&shrinker_rwsem);
	list_add_tail(&shrinker->list, &shrinker_list);
	up_write(&shrinker_rwsem);
}
EXPORT_SYMBOL(register_shrinker);

/*
 * Remove one
 */
void unregister_shrinker(struct shrinker *shrinker)
{
	down_write(&shrinker_rwsem);
	list_del(&shrinker->list);
	up_write(&shrinker_rwsem);
}
EXPORT_SYMBOL(unregister_shrinker);

#define SHRINK_BATCH 128
/*
 * Call the shrink functions to age shrinkable caches
 *
 * Here we assume it costs one seek to replace a lru page and that it also
 * takes a seek to recreate a cache object.  With this in mind we age equal
 * percentages of the lru and ageable caches.  This should balance the seeks
 * generated by these structures.
 *
 * If the vm encountered mapped pages on the LRU it increase the pressure on
 * slab to avoid swapping.
 *
 * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
 *
 * `lru_pages' represents the number of on-LRU pages in all the zones which
 * are eligible for the caller's allocation attempt.  It is used for balancing
 * slab reclaim versus page reclaim.
 *
 * Returns the number of slab objects which we shrunk.
 */
unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
			unsigned long lru_pages)
{
	struct shrinker *shrinker;
	unsigned long ret = 0;

	if (scanned == 0)
		scanned = SWAP_CLUSTER_MAX;

	if (!down_read_trylock(&shrinker_rwsem))
		return 1;	/* Assume we'll be able to shrink next time */

	list_for_each_entry(shrinker, &shrinker_list, list) {
		unsigned long long delta;
		unsigned long total_scan;
		unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask);

		delta = (4 * scanned) / shrinker->seeks;
		delta *= max_pass;
		do_div(delta, lru_pages + 1);
		shrinker->nr += delta;
		if (shrinker->nr < 0) {
			printk(KERN_ERR "%s: nr=%ld\n",
					__FUNCTION__, shrinker->nr);
			shrinker->nr = max_pass;
		}

		/*
		 * Avoid risking looping forever due to too large nr value:
		 * never try to free more than twice the estimate number of
		 * freeable entries.
		 */
		if (shrinker->nr > max_pass * 2)
			shrinker->nr = max_pass * 2;

		total_scan = shrinker->nr;
		shrinker->nr = 0;

		while (total_scan >= SHRINK_BATCH) {
			long this_scan = SHRINK_BATCH;
			int shrink_ret;
			int nr_before;

			nr_before = (*shrinker->shrink)(0, gfp_mask);
			shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask);
			if (shrink_ret == -1)
				break;
			if (shrink_ret < nr_before)
				ret += nr_before - shrink_ret;
			count_vm_events(SLABS_SCANNED, this_scan);
			total_scan -= this_scan;

			cond_resched();
		}

		shrinker->nr += total_scan;
	}
	up_read(&shrinker_rwsem);
	return ret;
}

/* Called without lock on whether page is mapped, so answer is unstable */
static inline int page_mapping_inuse(struct page *page)
{
	struct address_space *mapping;

	/* Page is in somebody's page tables. */
	if (page_mapped(page))
		return 1;

	/* Be more reluctant to reclaim swapcache than pagecache */
	if (PageSwapCache(page))
		return 1;

	mapping = page_mapping(page);
	if (!mapping)
		return 0;

	/* File is mmap'd by somebody? */
	return mapping_mapped(mapping);
}

static inline int is_page_cache_freeable(struct page *page)
{
	return page_count(page) - !!PagePrivate(page) == 2;
}

static int may_write_to_queue(struct backing_dev_info *bdi)
{
	if (current->flags & PF_SWAPWRITE)
		return 1;
	if (!bdi_write_congested(bdi))
		return 1;
	if (bdi == current->backing_dev_info)
		return 1;
	return 0;
}

/*
 * We detected a synchronous write error writing a page out.  Probably
 * -ENOSPC.  We need to propagate that into the address_space for a subsequent
 * fsync(), msync() or close().
 *
 * The tricky part is that after writepage we cannot touch the mapping: nothing
 * prevents it from being freed up.  But we have a ref on the page and once
 * that page is locked, the mapping is pinned.
 *
 * We're allowed to run sleeping lock_page() here because we know the caller has
 * __GFP_FS.
 */
static void handle_write_error(struct address_space *mapping,
				struct page *page, int error)
{
	lock_page(page);
	if (page_mapping(page) == mapping)
		mapping_set_error(mapping, error);
	unlock_page(page);
}

/* Request for sync pageout. */
enum pageout_io {
	PAGEOUT_IO_ASYNC,
	PAGEOUT_IO_SYNC,
};

/* possible outcome of pageout() */
typedef enum {
	/* failed to write page out, page is locked */
	PAGE_KEEP,
	/* move page to the active list, page is locked */
	PAGE_ACTIVATE,
	/* page has been sent to the disk successfully, page is unlocked */
	PAGE_SUCCESS,
	/* page is clean and locked */
	PAGE_CLEAN,
} pageout_t;

/*
 * pageout is called by shrink_page_list() for each dirty page.
 * Calls ->writepage().
 */
static pageout_t pageout(struct page *page, struct address_space *mapping,
						enum pageout_io sync_writeback)
{
	/*
	 * If the page is dirty, only perform writeback if that write
	 * will be non-blocking.  To prevent this allocation from being
	 * stalled by pagecache activity.  But note that there may be
	 * stalls if we need to run get_block().  We could test
	 * PagePrivate for that.
	 *
	 * If this process is currently in generic_file_write() against
	 * this page's queue, we can perform writeback even if that
	 * will block.
	 *
	 * If the page is swapcache, write it back even if that would
	 * block, for some throttling. This happens by accident, because
	 * swap_backing_dev_info is bust: it doesn't reflect the
	 * congestion state of the swapdevs.  Easy to fix, if needed.
	 * See swapfile.c:page_queue_congested().
	 */
	if (!is_page_cache_freeable(page))
		return PAGE_KEEP;
	if (!mapping) {
		/*
		 * Some data journaling orphaned pages can have
		 * page->mapping == NULL while being dirty with clean buffers.
		 */
		if (PagePrivate(page)) {
			if (try_to_free_buffers(page)) {
				ClearPageDirty(page);
				printk("%s: orphaned page\n", __FUNCTION__);
				return PAGE_CLEAN;
			}
		}
		return PAGE_KEEP;
	}
	if (mapping->a_ops->writepage == NULL)
		return PAGE_ACTIVATE;
	if (!may_write_to_queue(mapping->backing_dev_info))
		return PAGE_KEEP;

	if (clear_page_dirty_for_io(page)) {
		int res;
		struct writeback_control wbc = {
			.sync_mode = WB_SYNC_NONE,
			.nr_to_write = SWAP_CLUSTER_MAX,
			.range_start = 0,
			.range_end = LLONG_MAX,
			.nonblocking = 1,
			.for_reclaim = 1,
		};

		SetPageReclaim(page);
		res = mapping->a_ops->writepage(page, &wbc);
		if (res < 0)
			handle_write_error(mapping, page, res);
		if (res == AOP_WRITEPAGE_ACTIVATE) {
			ClearPageReclaim(page);
			return PAGE_ACTIVATE;
		}

		/*
		 * Wait on writeback if requested to. This happens when
		 * direct reclaiming a large contiguous area and the
		 * first attempt to free a range of pages fails.
		 */
		if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC)
			wait_on_page_writeback(page);

		if (!PageWriteback(page)) {
			/* synchronous write or broken a_ops? */
			ClearPageReclaim(page);
		}
		inc_zone_page_state(page, NR_VMSCAN_WRITE);
		return PAGE_SUCCESS;
	}

	return PAGE_CLEAN;
}

/*
 * Attempt to detach a locked page from its ->mapping.  If it is dirty or if
 * someone else has a ref on the page, abort and return 0.  If it was
 * successfully detached, return 1.  Assumes the caller has a single ref on
 * this page.
 */
int remove_mapping(struct address_space *mapping, struct page *page)
{
	BUG_ON(!PageLocked(page));
	BUG_ON(mapping != page_mapping(page));

	write_lock_irq(&mapping->tree_lock);
	/*
	 * The non racy check for a busy page.
	 *
	 * Must be careful with the order of the tests. When someone has
	 * a ref to the page, it may be possible that they dirty it then
	 * drop the reference. So if PageDirty is tested before page_count
	 * here, then the following race may occur:
	 *
	 * get_user_pages(&page);
	 * [user mapping goes away]
	 * write_to(page);
	 *				!PageDirty(page)    [good]
	 * SetPageDirty(page);
	 * put_page(page);
	 *				!page_count(page)   [good, discard it]
	 *
	 * [oops, our write_to data is lost]
	 *
	 * Reversing the order of the tests ensures such a situation cannot
	 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
	 * load is not satisfied before that of page->_count.
	 *
	 * Note that if SetPageDirty is always performed via set_page_dirty,
	 * and thus under tree_lock, then this ordering is not required.
	 */
	if (unlikely(page_count(page) != 2))
		goto cannot_free;
	smp_rmb();
	if (unlikely(PageDirty(page)))
		goto cannot_free;

	if (PageSwapCache(page)) {
		swp_entry_t swap = { .val = page_private(page) };
		__delete_from_swap_cache(page);
		write_unlock_irq(&mapping->tree_lock);
		swap_free(swap);
		__put_page(page);	/* The pagecache ref */
		return 1;
	}

	__remove_from_page_cache(page);
	write_unlock_irq(&mapping->tree_lock);
	__put_page(page);
	return 1;

cannot_free:
	write_unlock_irq(&mapping->tree_lock);
	return 0;
}

/*
 * shrink_page_list() returns the number of reclaimed pages
 */
static unsigned long shrink_page_list(struct list_head *page_list,
					struct scan_control *sc,
					enum pageout_io sync_writeback)
{
	LIST_HEAD(ret_pages);
	struct pagevec freed_pvec;
	int pgactivate = 0;
	unsigned long nr_reclaimed = 0;

	cond_resched();

	pagevec_init(&freed_pvec, 1);
	while (!list_empty(page_list)) {
		struct address_space *mapping;
		struct page *page;
		int may_enter_fs;
		int referenced;

		cond_resched();

		page = lru_to_page(page_list);
		list_del(&page->lru);

		if (TestSetPageLocked(page))
			goto keep;

		VM_BUG_ON(PageActive(page));

		sc->nr_scanned++;

		if (!sc->may_swap && page_mapped(page))
			goto keep_locked;

		/* Double the slab pressure for mapped and swapcache pages */
		if (page_mapped(page) || PageSwapCache(page))
			sc->nr_scanned++;

		may_enter_fs = (sc->gfp_mask & __GFP_FS) ||
			(PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));

		if (PageWriteback(page)) {
			/*
			 * Synchronous reclaim is performed in two passes,
			 * first an asynchronous pass over the list to
			 * start parallel writeback, and a second synchronous
			 * pass to wait for the IO to complete.  Wait here
			 * for any page for which writeback has already
			 * started.
			 */
			if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
				wait_on_page_writeback(page);
			else {
				sc->nr_io_pages++;
				goto keep_locked;
			}
		}

		referenced = page_referenced(page, 1, sc->mem_cgroup);
		/* In active use or really unfreeable?  Activate it. */
		if (sc->order <= PAGE_ALLOC_COSTLY_ORDER &&
					referenced && page_mapping_inuse(page))
			goto activate_locked;

#ifdef CONFIG_SWAP
		/*
		 * Anonymous process memory has backing store?
		 * Try to allocate it some swap space here.
		 */
		if (PageAnon(page) && !PageSwapCache(page))
			if (!add_to_swap(page, GFP_ATOMIC))
				goto activate_locked;
#endif /* CONFIG_SWAP */

		mapping = page_mapping(page);

		/*
		 * The page is mapped into the page tables of one or more
		 * processes. Try to unmap it here.
		 */
		if (page_mapped(page) && mapping) {
			switch (try_to_unmap(page, 0)) {
			case SWAP_FAIL:
				goto activate_locked;
			case SWAP_AGAIN:
				goto keep_locked;
			case SWAP_SUCCESS:
				; /* try to free the page below */
			}
		}

		if (PageDirty(page)) {
			if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
				goto keep_locked;
			if (!may_enter_fs) {
				sc->nr_io_pages++;
				goto keep_locked;
			}
			if (!sc->may_writepage)
				goto keep_locked;

			/* Page is dirty, try to write it out here */
			switch (pageout(page, mapping, sync_writeback)) {
			case PAGE_KEEP:
				goto keep_locked;
			case PAGE_ACTIVATE:
				goto activate_locked;
			case PAGE_SUCCESS:
				if (PageWriteback(page) || PageDirty(page)) {
					sc->nr_io_pages++;
					goto keep;
				}
				/*
				 * A synchronous write - probably a ramdisk.  Go
				 * ahead and try to reclaim the page.
				 */
				if (TestSetPageLocked(page))
					goto keep;
				if (PageDirty(page) || PageWriteback(page))
					goto keep_locked;
				mapping = page_mapping(page);
			case PAGE_CLEAN:
				; /* try to free the page below */
			}
		}

		/*
		 * If the page has buffers, try to free the buffer mappings
		 * associated with this page. If we succeed we try to free
		 * the page as well.
		 *
		 * We do this even if the page is PageDirty().
		 * try_to_release_page() does not perform I/O, but it is
		 * possible for a page to have PageDirty set, but it is actually
		 * clean (all its buffers are clean).  This happens if the
		 * buffers were written out directly, with submit_bh(). ext3
		 * will do this, as well as the blockdev mapping. 
		 * try_to_release_page() will discover that cleanness and will
		 * drop the buffers and mark the page clean - it can be freed.
		 *
		 * Rarely, pages can have buffers and no ->mapping.  These are
		 * the pages which were not successfully invalidated in
		 * truncate_complete_page().  We try to drop those buffers here
		 * and if that worked, and the page is no longer mapped into
		 * process address space (page_count == 1) it can be freed.
		 * Otherwise, leave the page on the LRU so it is swappable.
		 */
		if (PagePrivate(page)) {
			if (!try_to_release_page(page, sc->gfp_mask))
				goto activate_locked;
			if (!mapping && page_count(page) == 1)
				goto free_it;
		}

		if (!mapping || !remove_mapping(mapping, page))
			goto keep_locked;

free_it:
		unlock_page(page);
		nr_reclaimed++;
		if (!pagevec_add(&freed_pvec, page))
			__pagevec_release_nonlru(&freed_pvec);
		continue;

activate_locked:
		SetPageActive(page);
		pgactivate++;
keep_locked:
		unlock_page(page);
keep:
		list_add(&page->lru, &ret_pages);
		VM_BUG_ON(PageLRU(page));
	}
	list_splice(&ret_pages, page_list);
	if (pagevec_count(&freed_pvec))
		__pagevec_release_nonlru(&freed_pvec);
	count_vm_events(PGACTIVATE, pgactivate);
	return nr_reclaimed;
}

/* LRU Isolation modes. */
#define ISOLATE_INACTIVE 0	/* Isolate inactive pages. */
#define ISOLATE_ACTIVE 1	/* Isolate active pages. */
#define ISOLATE_BOTH 2		/* Isolate both active and inactive pages. */

/*
 * Attempt to remove the specified page from its LRU.  Only take this page
 * if it is of the appropriate PageActive status.  Pages which are being
 * freed elsewhere are also ignored.
 *
 * page:	page to consider
 * mode:	one of the LRU isolation modes defined above
 *
 * returns 0 on success, -ve errno on failure.
 */
int __isolate_lru_page(struct page *page, int mode)
{
	int ret = -EINVAL;

	/* Only take pages on the LRU. */
	if (!PageLRU(page))
		return ret;

	/*
	 * When checking the active state, we need to be sure we are
	 * dealing with comparible boolean values.  Take the logical not
	 * of each.
	 */
	if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
		return ret;

	ret = -EBUSY;
	if (likely(get_page_unless_zero(page))) {
		/*
		 * Be careful not to clear PageLRU until after we're
		 * sure the page is not being freed elsewhere -- the
		 * page release code relies on it.
		 */
		ClearPageLRU(page);
		ret = 0;
	}

	return ret;
}

/*
 * zone->lru_lock is heavily contended.  Some of the functions that
 * shrink the lists perform better by taking out a batch of pages
 * and working on them outside the LRU lock.
 *
 * For pagecache intensive workloads, this function is the hottest
 * spot in the kernel (apart from copy_*_user functions).
 *
 * Appropriate locks must be held before calling this function.
 *
 * @nr_to_scan:	The number of pages to look through on the list.
 * @src:	The LRU list to pull pages off.
 * @dst:	The temp list to put pages on to.
 * @scanned:	The number of pages that were scanned.
 * @order:	The caller's attempted allocation order
 * @mode:	One of the LRU isolation modes
 *
 * returns how many pages were moved onto *@dst.
 */
static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
		struct list_head *src, struct list_head *dst,
		unsigned long *scanned, int order, int mode)
{
	unsigned long nr_taken = 0;
	unsigned long scan;

	for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
		struct page *page;
		unsigned long pfn;
		unsigned long end_pfn;
		unsigned long page_pfn;
		int zone_id;

		page = lru_to_page(src);
		prefetchw_prev_lru_page(page, src, flags);

		VM_BUG_ON(!PageLRU(page));

		switch (__isolate_lru_page(page, mode)) {
		case 0:
			list_move(&page->lru, dst);
			nr_taken++;
			break;

		case -EBUSY:
			/* else it is being freed elsewhere */
			list_move(&page->lru, src);
			continue;

		default:
			BUG();
		}

		if (!order)
			continue;

		/*
		 * Attempt to take all pages in the order aligned region
		 * surrounding the tag page.  Only take those pages of
		 * the same active state as that tag page.  We may safely
		 * round the target page pfn down to the requested order
		 * as the mem_map is guarenteed valid out to MAX_ORDER,
		 * where that page is in a different zone we will detect
		 * it from its zone id and abort this block scan.
		 */
		zone_id = page_zone_id(page);
		page_pfn = page_to_pfn(page);
		pfn = page_pfn & ~((1 << order) - 1);
		end_pfn = pfn + (1 << order);
		for (; pfn < end_pfn; pfn++) {
			struct page *cursor_page;

			/* The target page is in the block, ignore it. */
			if (unlikely(pfn == page_pfn))
				continue;

			/* Avoid holes within the zone. */
			if (unlikely(!pfn_valid_within(pfn)))
				break;

			cursor_page = pfn_to_page(pfn);
			/* Check that we have not crossed a zone boundary. */
			if (unlikely(page_zone_id(cursor_page) != zone_id))
				continue;
			switch (__isolate_lru_page(cursor_page, mode)) {
			case 0:
				list_move(&cursor_page->lru, dst);
				nr_taken++;
				scan++;
				break;

			case -EBUSY:
				/* else it is being freed elsewhere */
				list_move(&cursor_page->lru, src);
			default:
				break;
			}
		}
	}

	*scanned = scan;
	return nr_taken;
}

static unsigned long isolate_pages_global(unsigned long nr,
					struct list_head *dst,
					unsigned long *scanned, int order,
					int mode, struct zone *z,
					struct mem_cgroup *mem_cont,
					int active)
{
	if (active)
		return isolate_lru_pages(nr, &z->active_list, dst,
						scanned, order, mode);
	else
		return isolate_lru_pages(nr, &z->inactive_list, dst,
						scanned, order, mode);
}

/*
 * clear_active_flags() is a helper for shrink_active_list(), clearing
 * any active bits from the pages in the list.
 */
static unsigned long clear_active_flags(struct list_head *page_list)
{
	int nr_active = 0;
	struct page *page;

	list_for_each_entry(page, page_list, lru)
		if (PageActive(page)) {
			ClearPageActive(page);
			nr_active++;
		}

	return nr_active;
}

/*
 * shrink_inactive_list() is a helper for shrink_zone().  It returns the number
 * of reclaimed pages
 */
static unsigned long shrink_inactive_list(unsigned long max_scan,
				struct zone *zone, struct scan_control *sc)
{
	LIST_HEAD(page_list);
	struct pagevec pvec;
	unsigned long nr_scanned = 0;
	unsigned long nr_reclaimed = 0;

	pagevec_init(&pvec, 1);

	lru_add_drain();
	spin_lock_irq(&zone->lru_lock);
	do {
		struct page *page;
		unsigned long nr_taken;
		unsigned long nr_scan;
		unsigned long nr_freed;
		unsigned long nr_active;

		nr_taken = sc->isolate_pages(sc->swap_cluster_max,
			     &page_list, &nr_scan, sc->order,
			     (sc->order > PAGE_ALLOC_COSTLY_ORDER)?
					     ISOLATE_BOTH : ISOLATE_INACTIVE,
				zone, sc->mem_cgroup, 0);
		nr_active = clear_active_flags(&page_list);
		__count_vm_events(PGDEACTIVATE, nr_active);

		__mod_zone_page_state(zone, NR_ACTIVE, -nr_active);
		__mod_zone_page_state(zone, NR_INACTIVE,
						-(nr_taken - nr_active));
		zone->pages_scanned += nr_scan;
		spin_unlock_irq(&zone->lru_lock);

		nr_scanned += nr_scan;
		nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);

		/*
		 * If we are direct reclaiming for contiguous pages and we do
		 * not reclaim everything in the list, try again and wait
		 * for IO to complete. This will stall high-order allocations
		 * but that should be acceptable to the caller
		 */
		if (nr_freed < nr_taken && !current_is_kswapd() &&
					sc->order > PAGE_ALLOC_COSTLY_ORDER) {
			congestion_wait(WRITE, HZ/10);

			/*
			 * The attempt at page out may have made some
			 * of the pages active, mark them inactive again.
			 */
			nr_active = clear_active_flags(&page_list);
			count_vm_events(PGDEACTIVATE, nr_active);

			nr_freed += shrink_page_list(&page_list, sc,
							PAGEOUT_IO_SYNC);
		}

		nr_reclaimed += nr_freed;
		local_irq_disable();
		if (current_is_kswapd()) {
			__count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan);
			__count_vm_events(KSWAPD_STEAL, nr_freed);
		} else
			__count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan);
		__count_zone_vm_events(PGSTEAL, zone, nr_freed);

		if (nr_taken == 0)
			goto done;

		spin_lock(&zone->lru_lock);
		/*
		 * Put back any unfreeable pages.
		 */
		while (!list_empty(&page_list)) {
			page = lru_to_page(&page_list);
			VM_BUG_ON(PageLRU(page));
			SetPageLRU(page);
			list_del(&page->lru);
			if (PageActive(page))
				add_page_to_active_list(zone, page);
			else
				add_page_to_inactive_list(zone, page);
			if (!pagevec_add(&pvec, page)) {
				spin_unlock_irq(&zone->lru_lock);
				__pagevec_release(&pvec);
				spin_lock_irq(&zone->lru_lock);
			}
		}
  	} while (nr_scanned < max_scan);
	spin_unlock(&zone->lru_lock);
done:
	local_irq_enable();
	pagevec_release(&pvec);
	return nr_reclaimed;
}

/*
 * We are about to scan this zone at a certain priority level.  If that priority
 * level is smaller (ie: more urgent) than the previous priority, then note
 * that priority level within the zone.  This is done so that when the next
 * process comes in to scan this zone, it will immediately start out at this
 * priority level rather than having to build up its own scanning priority.
 * Here, this priority affects only the reclaim-mapped threshold.
 */
static inline void note_zone_scanning_priority(struct zone *zone, int priority)
{
	if (priority < zone->prev_priority)
		zone->prev_priority = priority;
}

static inline int zone_is_near_oom(struct zone *zone)
{
	return zone->pages_scanned >= (zone_page_state(zone, NR_ACTIVE)
				+ zone_page_state(zone, NR_INACTIVE))*3;
}

/*
 * This moves pages from the active list to the inactive list.
 *
 * We move them the other way if the page is referenced by one or more
 * processes, from rmap.
 *
 * If the pages are mostly unmapped, the processing is fast and it is
 * appropriate to hold zone->lru_lock across the whole operation.  But if
 * the pages are mapped, the processing is slow (page_referenced()) so we
 * should drop zone->lru_lock around each page.  It's impossible to balance
 * this, so instead we remove the pages from the LRU while processing them.
 * It is safe to rely on PG_active against the non-LRU pages in here because
 * nobody will play with that bit on a non-LRU page.
 *
 * The downside is that we have to touch page->_count against each page.
 * But we had to alter page->flags anyway.
 */
static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
				struct scan_control *sc, int priority)
{
	unsigned long pgmoved;
	int pgdeactivate = 0;
	unsigned long pgscanned;
	LIST_HEAD(l_hold);	/* The pages which were snipped off */
	LIST_HEAD(l_inactive);	/* Pages to go onto the inactive_list */
	LIST_HEAD(l_active);	/* Pages to go onto the active_list */
	struct page *page;
	struct pagevec pvec;
	int reclaim_mapped = 0;

	if (sc->may_swap) {
		long mapped_ratio;
		long distress;
		long swap_tendency;
		long imbalance;

		if (zone_is_near_oom(zone))
			goto force_reclaim_mapped;

		/*
		 * `distress' is a measure of how much trouble we're having
		 * reclaiming pages.  0 -> no problems.  100 -> great trouble.
		 */
		distress = 100 >> min(zone->prev_priority, priority);

		/*
		 * The point of this algorithm is to decide when to start
		 * reclaiming mapped memory instead of just pagecache.  Work out
		 * how much memory
		 * is mapped.
		 */
		mapped_ratio = ((global_page_state(NR_FILE_MAPPED) +
				global_page_state(NR_ANON_PAGES)) * 100) /
					vm_total_pages;

		/*
		 * Now decide how much we really want to unmap some pages.  The
		 * mapped ratio is downgraded - just because there's a lot of
		 * mapped memory doesn't necessarily mean that page reclaim
		 * isn't succeeding.
		 *
		 * The distress ratio is important - we don't want to start
		 * going oom.
		 *
		 * A 100% value of vm_swappiness overrides this algorithm
		 * altogether.
		 */
		swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;

		/*
		 * If there's huge imbalance between active and inactive
		 * (think active 100 times larger than inactive) we should
		 * become more permissive, or the system will take too much
		 * cpu before it start swapping during memory pressure.
		 * Distress is about avoiding early-oom, this is about
		 * making swappiness graceful despite setting it to low
		 * values.
		 *
		 * Avoid div by zero with nr_inactive+1, and max resulting
		 * value is vm_total_pages.
		 */
		imbalance  = zone_page_state(zone, NR_ACTIVE);
		imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;

		/*
		 * Reduce the effect of imbalance if swappiness is low,
		 * this means for a swappiness very low, the imbalance
		 * must be much higher than 100 for this logic to make
		 * the difference.
		 *
		 * Max temporary value is vm_total_pages*100.
		 */
		imbalance *= (vm_swappiness + 1);
		imbalance /= 100;

		/*
		 * If not much of the ram is mapped, makes the imbalance
		 * less relevant, it's high priority we refill the inactive
		 * list with mapped pages only in presence of high ratio of
		 * mapped pages.
		 *
		 * Max temporary value is vm_total_pages*100.
		 */
		imbalance *= mapped_ratio;
		imbalance /= 100;

		/* apply imbalance feedback to swap_tendency */
		swap_tendency += imbalance;

		/*
		 * Now use this metric to decide whether to start moving mapped
		 * memory onto the inactive list.
		 */
		if (swap_tendency >= 100)
force_reclaim_mapped:
			reclaim_mapped = 1;
	}

	lru_add_drain();
	spin_lock_irq(&zone->lru_lock);
	pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
					ISOLATE_ACTIVE, zone,
					sc->mem_cgroup, 1);
	zone->pages_scanned += pgscanned;
	__mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
	spin_unlock_irq(&zone->lru_lock);

	while (!list_empty(&l_hold)) {
		cond_resched();
		page = lru_to_page(&l_hold);
		list_del(&page->lru);
		if (page_mapped(page)) {
			if (!reclaim_mapped ||
			    (total_swap_pages == 0 && PageAnon(page)) ||
			    page_referenced(page, 0, sc->mem_cgroup)) {
				list_add(&page->lru, &l_active);
				continue;
			}
		}
		list_add(&page->lru, &l_inactive);
	}

	pagevec_init(&pvec, 1);
	pgmoved = 0;
	spin_lock_irq(&zone->lru_lock);
	while (!list_empty(&l_inactive)) {
		page = lru_to_page(&l_inactive);
		prefetchw_prev_lru_page(page, &l_inactive, flags);
		VM_BUG_ON(PageLRU(page));
		SetPageLRU(page);
		VM_BUG_ON(!PageActive(page));
		ClearPageActive(page);

		list_move(&page->lru, &zone->inactive_list);
		mem_cgroup_move_lists(page_get_page_cgroup(page), false);
		pgmoved++;
		if (!pagevec_add(&pvec, page)) {
			__mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
			spin_unlock_irq(&zone->lru_lock);
			pgdeactivate += pgmoved;
			pgmoved = 0;
			if (buffer_heads_over_limit)
				pagevec_strip(&pvec);
			__pagevec_release(&pvec);
			spin_lock_irq(&zone->lru_lock);
		}
	}
	__mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
	pgdeactivate += pgmoved;
	if (buffer_heads_over_limit) {
		spin_unlock_irq(&zone->lru_lock);
		pagevec_strip(&pvec);
		spin_lock_irq(&zone->lru_lock);
	}

	pgmoved = 0;
	while (!list_empty(&l_active)) {
		page = lru_to_page(&l_active);
		prefetchw_prev_lru_page(page, &l_active, flags);
		VM_BUG_ON(PageLRU(page));
		SetPageLRU(page);
		VM_BUG_ON(!PageActive(page));
		list_move(&page->lru, &zone->active_list);
		mem_cgroup_move_lists(page_get_page_cgroup(page), true);
		pgmoved++;
		if (!pagevec_add(&pvec, page)) {
			__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
			pgmoved = 0;
			spin_unlock_irq(&zone->lru_lock);
			__pagevec_release(&pvec);
			spin_lock_irq(&zone->lru_lock);
		}
	}
	__mod_zone_page_state(zone, NR_ACTIVE, pgmoved);

	__count_zone_vm_events(PGREFILL, zone, pgscanned);
	__count_vm_events(PGDEACTIVATE, pgdeactivate);
	spin_unlock_irq(&zone->lru_lock);

	pagevec_release(&pvec);
}

/*
 * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
 */
static unsigned long shrink_zone(int priority, struct zone *zone,
				struct scan_control *sc)
{
	unsigned long nr_active;
	unsigned long nr_inactive;
	unsigned long nr_to_scan;
	unsigned long nr_reclaimed = 0;

	/*
	 * Add one to `nr_to_scan' just to make sure that the kernel will
	 * slowly sift through the active list.
	 */
	zone->nr_scan_active +=
		(zone_page_state(zone, NR_ACTIVE) >> priority) + 1;
	nr_active = zone->nr_scan_active;
	if (nr_active >= sc->swap_cluster_max)
		zone->nr_scan_active = 0;
	else
		nr_active = 0;

	zone->nr_scan_inactive +=
		(zone_page_state(zone, NR_INACTIVE) >> priority) + 1;
	nr_inactive = zone->nr_scan_inactive;
	if (nr_inactive >= sc->swap_cluster_max)
		zone->nr_scan_inactive = 0;
	else
		nr_inactive = 0;

	while (nr_active || nr_inactive) {
		if (nr_active) {
			nr_to_scan = min(nr_active,
					(unsigned long)sc->swap_cluster_max);
			nr_active -= nr_to_scan;
			shrink_active_list(nr_to_scan, zone, sc, priority);
		}

		if (nr_inactive) {
			nr_to_scan = min(nr_inactive,
					(unsigned long)sc->swap_cluster_max);
			nr_inactive -= nr_to_scan;
			nr_reclaimed += shrink_inactive_list(nr_to_scan, zone,
								sc);
		}
	}

	throttle_vm_writeout(sc->gfp_mask);
	return nr_reclaimed;
}

/*
 * This is the direct reclaim path, for page-allocating processes.  We only
 * try to reclaim pages from zones which will satisfy the caller's allocation
 * request.
 *
 * We reclaim from a zone even if that zone is over pages_high.  Because:
 * a) The caller may be trying to free *extra* pages to satisfy a higher-order
 *    allocation or
 * b) The zones may be over pages_high but they must go *over* pages_high to
 *    satisfy the `incremental min' zone defense algorithm.
 *
 * Returns the number of reclaimed pages.
 *
 * If a zone is deemed to be full of pinned pages then just give it a light
 * scan then give up on it.
 */
static unsigned long shrink_zones(int priority, struct zone **zones,
					struct scan_control *sc)
{
	unsigned long nr_reclaimed = 0;
	int i;

	sc->all_unreclaimable = 1;
	for (i = 0; zones[i] != NULL; i++) {
		struct zone *zone = zones[i];

		if (!populated_zone(zone))
			continue;

		if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
			continue;

		note_zone_scanning_priority(zone, priority);

		if (zone_is_all_unreclaimable(zone) && priority != DEF_PRIORITY)
			continue;	/* Let kswapd poll it */

		sc->all_unreclaimable = 0;

		nr_reclaimed += shrink_zone(priority, zone, sc);
	}
	return nr_reclaimed;
}
 
/*
 * This is the main entry point to direct page reclaim.
 *
 * If a full scan of the inactive list fails to free enough memory then we
 * are "out of memory" and something needs to be killed.
 *
 * If the caller is !__GFP_FS then the probability of a failure is reasonably
 * high - the zone may be full of dirty or under-writeback pages, which this
 * caller can't do much about.  We kick pdflush and take explicit naps in the
 * hope that some of these pages can be written.  But if the allocating task
 * holds filesystem locks which prevent writeout this might not work, and the
 * allocation attempt will fail.
 */
static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
					  struct scan_control *sc)
{
	int priority;
	int ret = 0;
	unsigned long total_scanned = 0;
	unsigned long nr_reclaimed = 0;
	struct reclaim_state *reclaim_state = current->reclaim_state;
	unsigned long lru_pages = 0;
	int i;

	count_vm_event(ALLOCSTALL);

	for (i = 0; zones[i] != NULL; i++) {
		struct zone *zone = zones[i];

		if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
			continue;

		lru_pages += zone_page_state(zone, NR_ACTIVE)
				+ zone_page_state(zone, NR_INACTIVE);
	}

	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
		sc->nr_scanned = 0;
		sc->nr_io_pages = 0;
		if (!priority)
			disable_swap_token();
		nr_reclaimed += shrink_zones(priority, zones, sc);
		/*
		 * Don't shrink slabs when reclaiming memory from
		 * over limit cgroups
		 */
		if (sc->mem_cgroup == NULL)
			shrink_slab(sc->nr_scanned, gfp_mask, lru_pages);
		if (reclaim_state) {
			nr_reclaimed += reclaim_state->reclaimed_slab;
			reclaim_state->reclaimed_slab = 0;
		}
		total_scanned += sc->nr_scanned;
		if (nr_reclaimed >= sc->swap_cluster_max) {
			ret = 1;
			goto out;
		}

		/*
		 * Try to write back as many pages as we just scanned.  This
		 * tends to cause slow streaming writers to write data to the
		 * disk smoothly, at the dirtying rate, which is nice.   But
		 * that's undesirable in laptop mode, where we *want* lumpy
		 * writeout.  So in laptop mode, write out the whole world.
		 */
		if (total_scanned > sc->swap_cluster_max +
					sc->swap_cluster_max / 2) {
			wakeup_pdflush(laptop_mode ? 0 : total_scanned);
			sc->may_writepage = 1;
		}

		/* Take a nap, wait for some writeback to complete */
		if (sc->nr_scanned && priority < DEF_PRIORITY - 2 &&
				sc->nr_io_pages > sc->swap_cluster_max)
			congestion_wait(WRITE, HZ/10);
	}
	/* top priority shrink_caches still had more to do? don't OOM, then */
	if (!sc->all_unreclaimable && sc->mem_cgroup == NULL)
		ret = 1;
out:
	/*
	 * Now that we've scanned all the zones at this priority level, note
	 * that level within the zone so that the next thread which performs
	 * scanning of this zone will immediately start out at this priority
	 * level.  This affects only the decision whether or not to bring
	 * mapped pages onto the inactive list.
	 */
	if (priority < 0)
		priority = 0;
	for (i = 0; zones[i] != NULL; i++) {
		struct zone *zone = zones[i];

		if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
			continue;

		zone->prev_priority = priority;
	}
	return ret;
}

unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
{
	struct scan_control sc = {
		.gfp_mask = gfp_mask,
		.may_writepage = !laptop_mode,
		.swap_cluster_max = SWAP_CLUSTER_MAX,
		.may_swap = 1,
		.swappiness = vm_swappiness,
		.order = order,
		.mem_cgroup = NULL,
		.isolate_pages = isolate_pages_global,
	};

	return do_try_to_free_pages(zones, gfp_mask, &sc);
}

#ifdef CONFIG_CGROUP_MEM_CONT

unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
						gfp_t gfp_mask)
{
	struct scan_control sc = {
		.gfp_mask = gfp_mask,
		.may_writepage = !laptop_mode,
		.may_swap = 1,
		.swap_cluster_max = SWAP_CLUSTER_MAX,
		.swappiness = vm_swappiness,
		.order = 0,
		.mem_cgroup = mem_cont,
		.isolate_pages = mem_cgroup_isolate_pages,
	};
	int node;
	struct zone **zones;
	int target_zone = gfp_zone(GFP_HIGHUSER_MOVABLE);

	for_each_online_node(node) {
		zones = NODE_DATA(node)->node_zonelists[target_zone].zones;
		if (do_try_to_free_pages(zones, sc.gfp_mask, &sc))
			return 1;
	}
	return 0;
}
#endif

/*
 * For kswapd, balance_pgdat() will work across all this node's zones until
 * they are all at pages_high.
 *
 * Returns the number of pages which were actually freed.
 *
 * There is special handling here for zones which are full of pinned pages.
 * This can happen if the pages are all mlocked, or if they are all used by
 * device drivers (say, ZONE_DMA).  Or if they are all in use by hugetlb.
 * What we do is to detect the case where all pages in the zone have been
 * scanned twice and there has been zero successful reclaim.  Mark the zone as
 * dead and from now on, only perform a short scan.  Basically we're polling
 * the zone for when the problem goes away.
 *
 * kswapd scans the zones in the highmem->normal->dma direction.  It skips
 * zones which have free_pages > pages_high, but once a zone is found to have
 * free_pages <= pages_high, we scan that zone and the lower zones regardless
 * of the number of free pages in the lower zones.  This interoperates with
 * the page allocator fallback scheme to ensure that aging of pages is balanced
 * across the zones.
 */
static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
{
	int all_zones_ok;
	int priority;
	int i;
	unsigned long total_scanned;
	unsigned long nr_reclaimed;
	struct reclaim_state *reclaim_state = current->reclaim_state;
	struct scan_control sc = {
		.gfp_mask = GFP_KERNEL,
		.may_swap = 1,
		.swap_cluster_max = SWAP_CLUSTER_MAX,
		.swappiness = vm_swappiness,
		.order = order,
		.mem_cgroup = NULL,
		.isolate_pages = isolate_pages_global,
	};
	/*
	 * temp_priority is used to remember the scanning priority at which
	 * this zone was successfully refilled to free_pages == pages_high.
	 */
	int temp_priority[MAX_NR_ZONES];

loop_again:
	total_scanned = 0;
	nr_reclaimed = 0;
	sc.may_writepage = !laptop_mode;
	count_vm_event(PAGEOUTRUN);

	for (i = 0; i < pgdat->nr_zones; i++)
		temp_priority[i] = DEF_PRIORITY;

	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
		int end_zone = 0;	/* Inclusive.  0 = ZONE_DMA */
		unsigned long lru_pages = 0;

		/* The swap token gets in the way of swapout... */
		if (!priority)
			disable_swap_token();

		sc.nr_io_pages = 0;
		all_zones_ok = 1;

		/*
		 * Scan in the highmem->dma direction for the highest
		 * zone which needs scanning
		 */
		for (i = pgdat->nr_zones - 1; i >= 0; i--) {
			struct zone *zone = pgdat->node_zones + i;

			if (!populated_zone(zone))
				continue;

			if (zone_is_all_unreclaimable(zone) &&
			    priority != DEF_PRIORITY)
				continue;

			if (!zone_watermark_ok(zone, order, zone->pages_high,
					       0, 0)) {
				end_zone = i;
				break;
			}
		}
		if (i < 0)
			goto out;

		for (i = 0; i <= end_zone; i++) {
			struct zone *zone = pgdat->node_zones + i;

			lru_pages += zone_page_state(zone, NR_ACTIVE)
					+ zone_page_state(zone, NR_INACTIVE);
		}

		/*
		 * Now scan the zone in the dma->highmem direction, stopping
		 * at the last zone which needs scanning.
		 *
		 * We do this because the page allocator works in the opposite
		 * direction.  This prevents the page allocator from allocating
		 * pages behind kswapd's direction of progress, which would
		 * cause too much scanning of the lower zones.
		 */
		for (i = 0; i <= end_zone; i++) {
			struct zone *zone = pgdat->node_zones + i;
			int nr_slab;

			if (!populated_zone(zone))
				continue;

			if (zone_is_all_unreclaimable(zone) &&
					priority != DEF_PRIORITY)
				continue;

			if (!zone_watermark_ok(zone, order, zone->pages_high,
					       end_zone, 0))
				all_zones_ok = 0;
			temp_priority[i] = priority;
			sc.nr_scanned = 0;
			note_zone_scanning_priority(zone, priority);
			/*
			 * We put equal pressure on every zone, unless one
			 * zone has way too many pages free already.
			 */
			if (!zone_watermark_ok(zone, order, 8*zone->pages_high,
						end_zone, 0))
				nr_reclaimed += shrink_zone(priority, zone, &sc);
			reclaim_state->reclaimed_slab = 0;
			nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
						lru_pages);
			nr_reclaimed += reclaim_state->reclaimed_slab;
			total_scanned += sc.nr_scanned;
			if (zone_is_all_unreclaimable(zone))
				continue;
			if (nr_slab == 0 && zone->pages_scanned >=
				(zone_page_state(zone, NR_ACTIVE)
				+ zone_page_state(zone, NR_INACTIVE)) * 6)
					zone_set_flag(zone,
						      ZONE_ALL_UNRECLAIMABLE);
			/*
			 * If we've done a decent amount of scanning and
			 * the reclaim ratio is low, start doing writepage
			 * even in laptop mode
			 */
			if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
			    total_scanned > nr_reclaimed + nr_reclaimed / 2)
				sc.may_writepage = 1;
		}
		if (all_zones_ok)
			break;		/* kswapd: all done */
		/*
		 * OK, kswapd is getting into trouble.  Take a nap, then take
		 * another pass across the zones.
		 */
		if (total_scanned && priority < DEF_PRIORITY - 2 &&
					sc.nr_io_pages > sc.swap_cluster_max)
			congestion_wait(WRITE, HZ/10);

		/*
		 * We do this so kswapd doesn't build up large priorities for
		 * example when it is freeing in parallel with allocators. It
		 * matches the direct reclaim path behaviour in terms of impact
		 * on zone->*_priority.
		 */
		if (nr_reclaimed >= SWAP_CLUSTER_MAX)
			break;
	}
out:
	/*
	 * Note within each zone the priority level at which this zone was
	 * brought into a happy state.  So that the next thread which scans this
	 * zone will start out at that priority level.
	 */
	for (i = 0; i < pgdat->nr_zones; i++) {
		struct zone *zone = pgdat->node_zones + i;

		zone->prev_priority = temp_priority[i];
	}
	if (!all_zones_ok) {
		cond_resched();

		try_to_freeze();

		goto loop_again;
	}

	return nr_reclaimed;
}

/*
 * The background pageout daemon, started as a kernel thread
 * from the init process. 
 *
 * This basically trickles out pages so that we have _some_
 * free memory available even if there is no other activity
 * that frees anything up. This is needed for things like routing
 * etc, where we otherwise might have all activity going on in
 * asynchronous contexts that cannot page things out.
 *
 * If there are applications that are active memory-allocators
 * (most normal use), this basically shouldn't matter.
 */
static int kswapd(void *p)
{
	unsigned long order;
	pg_data_t *pgdat = (pg_data_t*)p;
	struct task_struct *tsk = current;
	DEFINE_WAIT(wait);
	struct reclaim_state reclaim_state = {
		.reclaimed_slab = 0,
	};
	cpumask_t cpumask;

	cpumask = node_to_cpumask(pgdat->node_id);
	if (!cpus_empty(cpumask))
		set_cpus_allowed(tsk, cpumask);
	current->reclaim_state = &reclaim_state;

	/*
	 * Tell the memory management that we're a "memory allocator",
	 * and that if we need more memory we should get access to it
	 * regardless (see "__alloc_pages()"). "kswapd" should
	 * never get caught in the normal page freeing logic.
	 *
	 * (Kswapd normally doesn't need memory anyway, but sometimes
	 * you need a small amount of memory in order to be able to
	 * page out something else, and this flag essentially protects
	 * us from recursively trying to free more memory as we're
	 * trying to free the first piece of memory in the first place).
	 */
	tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
	set_freezable();

	order = 0;
	for ( ; ; ) {
		unsigned long new_order;

		prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
		new_order = pgdat->kswapd_max_order;
		pgdat->kswapd_max_order = 0;
		if (order < new_order) {
			/*
			 * Don't sleep if someone wants a larger 'order'
			 * allocation
			 */
			order = new_order;
		} else {
			if (!freezing(current))
				schedule();

			order = pgdat->kswapd_max_order;
		}
		finish_wait(&pgdat->kswapd_wait, &wait);

		if (!try_to_freeze()) {
			/* We can speed up thawing tasks if we don't call
			 * balance_pgdat after returning from the refrigerator
			 */
			balance_pgdat(pgdat, order);
		}
	}
	return 0;
}

/*
 * A zone is low on free memory, so wake its kswapd task to service it.
 */
void wakeup_kswapd(struct zone *zone, int order)
{
	pg_data_t *pgdat;

	if (!populated_zone(zone))
		return;

	pgdat = zone->zone_pgdat;
	if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0))
		return;
	if (pgdat->kswapd_max_order < order)
		pgdat->kswapd_max_order = order;
	if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
		return;
	if (!waitqueue_active(&pgdat->kswapd_wait))
		return;
	wake_up_interruptible(&pgdat->kswapd_wait);
}

#ifdef CONFIG_PM
/*
 * Helper function for shrink_all_memory().  Tries to reclaim 'nr_pages' pages
 * from LRU lists system-wide, for given pass and priority, and returns the
 * number of reclaimed pages
 *
 * For pass > 3 we also try to shrink the LRU lists that contain a few pages
 */
static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
				      int pass, struct scan_control *sc)
{
	struct zone *zone;
	unsigned long nr_to_scan, ret = 0;

	for_each_zone(zone) {

		if (!populated_zone(zone))
			continue;

		if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
			continue;

		/* For pass = 0 we don't shrink the active list */
		if (pass > 0) {
			zone->nr_scan_active +=
				(zone_page_state(zone, NR_ACTIVE) >> prio) + 1;