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Root/mm/memory.c

1	/*
2	* linux/mm/memory.c
3	*
4	* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5	*/
6
7	/*
8	* demand-loading started 01.12.91 - seems it is high on the list of
9	* things wanted, and it should be easy to implement. - Linus
10	*/
11
12	/*
13	* Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14	* pages started 02.12.91, seems to work. - Linus.
15	*
16	* Tested sharing by executing about 30 /bin/sh: under the old kernel it
17	* would have taken more than the 6M I have free, but it worked well as
18	* far as I could see.
19	*
20	* Also corrected some "invalidate()"s - I wasn't doing enough of them.
21	*/
22
23	/*
24	* Real VM (paging to/from disk) started 18.12.91. Much more work and
25	* thought has to go into this. Oh, well..
26	* 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
27	* Found it. Everything seems to work now.
28	* 20.12.91 - Ok, making the swap-device changeable like the root.
29	*/
30
31	/*
32	* 05.04.94 - Multi-page memory management added for v1.1.
33	* Idea by Alex Bligh (alex@cconcepts.co.uk)
34	*
35	* 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36	* (Gerhard.Wichert@pdb.siemens.de)
37	*
38	* Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39	*/
40
41	#include <linux/kernel_stat.h>
42	#include <linux/mm.h>
43	#include <linux/hugetlb.h>
44	#include <linux/mman.h>
45	#include <linux/swap.h>
46	#include <linux/highmem.h>
47	#include <linux/pagemap.h>
48	#include <linux/ksm.h>
49	#include <linux/rmap.h>
50	#include <linux/export.h>
51	#include <linux/delayacct.h>
52	#include <linux/init.h>
53	#include <linux/writeback.h>
54	#include <linux/memcontrol.h>
55	#include <linux/mmu_notifier.h>
56	#include <linux/kallsyms.h>
57	#include <linux/swapops.h>
58	#include <linux/elf.h>
59	#include <linux/gfp.h>
60	#include <linux/migrate.h>
61	#include <linux/string.h>
62
63	#include <asm/io.h>
64	#include <asm/pgalloc.h>
65	#include <asm/uaccess.h>
66	#include <asm/tlb.h>
67	#include <asm/tlbflush.h>
68	#include <asm/pgtable.h>
69
70	#include "internal.h"
71
72	#ifdef LAST_NID_NOT_IN_PAGE_FLAGS
73	#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_nid.
74	#endif
75
76	#ifndef CONFIG_NEED_MULTIPLE_NODES
77	/* use the per-pgdat data instead for discontigmem - mbligh */
78	unsigned long max_mapnr;
79	struct page *mem_map;
80
81	EXPORT_SYMBOL(max_mapnr);
82	EXPORT_SYMBOL(mem_map);
83	#endif
84
85	/*
86	* A number of key systems in x86 including ioremap() rely on the assumption
87	* that high_memory defines the upper bound on direct map memory, then end
88	* of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
89	* highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
90	* and ZONE_HIGHMEM.
91	*/
92	void * high_memory;
93
94	EXPORT_SYMBOL(high_memory);
95
96	/*
97	* Randomize the address space (stacks, mmaps, brk, etc.).
98	*
99	* ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
100	* as ancient (libc5 based) binaries can segfault. )
101	*/
102	int randomize_va_space __read_mostly =
103	#ifdef CONFIG_COMPAT_BRK
104	1;
105	#else
106	2;
107	#endif
108
109	static int __init disable_randmaps(char *s)
110	{
111	randomize_va_space = 0;
112	return 1;
113	}
114	__setup("norandmaps", disable_randmaps);
115
116	unsigned long zero_pfn __read_mostly;
117	unsigned long highest_memmap_pfn __read_mostly;
118
119	/*
120	* CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
121	*/
122	static int __init init_zero_pfn(void)
123	{
124	zero_pfn = page_to_pfn(ZERO_PAGE(0));
125	return 0;
126	}
127	core_initcall(init_zero_pfn);
128
129
130	#if defined(SPLIT_RSS_COUNTING)
131
132	void sync_mm_rss(struct mm_struct *mm)
133	{
134	int i;
135
136	for (i = 0; i < NR_MM_COUNTERS; i++) {
137	if (current->rss_stat.count[i]) {
138	add_mm_counter(mm, i, current->rss_stat.count[i]);
139	current->rss_stat.count[i] = 0;
140	}
141	}
142	current->rss_stat.events = 0;
143	}
144
145	static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
146	{
147	struct task_struct *task = current;
148
149	if (likely(task->mm == mm))
150	task->rss_stat.count[member] += val;
151	else
152	add_mm_counter(mm, member, val);
153	}
154	#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
155	#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
156
157	/* sync counter once per 64 page faults */
158	#define TASK_RSS_EVENTS_THRESH (64)
159	static void check_sync_rss_stat(struct task_struct *task)
160	{
161	if (unlikely(task != current))
162	return;
163	if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
164	sync_mm_rss(task->mm);
165	}
166	#else /* SPLIT_RSS_COUNTING */
167
168	#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
169	#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
170
171	static void check_sync_rss_stat(struct task_struct *task)
172	{
173	}
174
175	#endif /* SPLIT_RSS_COUNTING */
176
177	#ifdef HAVE_GENERIC_MMU_GATHER
178
179	static int tlb_next_batch(struct mmu_gather *tlb)
180	{
181	struct mmu_gather_batch *batch;
182
183	batch = tlb->active;
184	if (batch->next) {
185	tlb->active = batch->next;
186	return 1;
187	}
188
189	if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
190	return 0;
191
192	batch = (void *)__get_free_pages(GFP_NOWAIT \| __GFP_NOWARN, 0);
193	if (!batch)
194	return 0;
195
196	tlb->batch_count++;
197	batch->next = NULL;
198	batch->nr = 0;
199	batch->max = MAX_GATHER_BATCH;
200
201	tlb->active->next = batch;
202	tlb->active = batch;
203
204	return 1;
205	}
206
207	/* tlb_gather_mmu
208	* Called to initialize an (on-stack) mmu_gather structure for page-table
209	* tear-down from @mm. The @fullmm argument is used when @mm is without
210	* users and we're going to destroy the full address space (exit/execve).
211	*/
212	void tlb_gather_mmu(struct mmu_gather tlb, struct mm_struct mm, unsigned long start, unsigned long end)
213	{
214	tlb->mm = mm;
215
216	/* Is it from 0 to ~0? */
217	tlb->fullmm = !(start \| (end+1));
218	tlb->need_flush_all = 0;
219	tlb->start = start;
220	tlb->end = end;
221	tlb->need_flush = 0;
222	tlb->local.next = NULL;
223	tlb->local.nr = 0;
224	tlb->local.max = ARRAY_SIZE(tlb->__pages);
225	tlb->active = &tlb->local;
226	tlb->batch_count = 0;
227
228	#ifdef CONFIG_HAVE_RCU_TABLE_FREE
229	tlb->batch = NULL;
230	#endif
231	}
232
233	void tlb_flush_mmu(struct mmu_gather *tlb)
234	{
235	struct mmu_gather_batch *batch;
236
237	if (!tlb->need_flush)
238	return;
239	tlb->need_flush = 0;
240	tlb_flush(tlb);
241	#ifdef CONFIG_HAVE_RCU_TABLE_FREE
242	tlb_table_flush(tlb);
243	#endif
244
245	for (batch = &tlb->local; batch; batch = batch->next) {
246	free_pages_and_swap_cache(batch->pages, batch->nr);
247	batch->nr = 0;
248	}
249	tlb->active = &tlb->local;
250	}
251
252	/* tlb_finish_mmu
253	* Called at the end of the shootdown operation to free up any resources
254	* that were required.
255	*/
256	void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
257	{
258	struct mmu_gather_batch batch, next;
259
260	tlb_flush_mmu(tlb);
261
262	/* keep the page table cache within bounds */
263	check_pgt_cache();
264
265	for (batch = tlb->local.next; batch; batch = next) {
266	next = batch->next;
267	free_pages((unsigned long)batch, 0);
268	}
269	tlb->local.next = NULL;
270	}
271
272	/* __tlb_remove_page
273	* Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
274	* handling the additional races in SMP caused by other CPUs caching valid
275	* mappings in their TLBs. Returns the number of free page slots left.
276	* When out of page slots we must call tlb_flush_mmu().
277	*/
278	int __tlb_remove_page(struct mmu_gather tlb, struct page page)
279	{
280	struct mmu_gather_batch *batch;
281
282	VM_BUG_ON(!tlb->need_flush);
283
284	batch = tlb->active;
285	batch->pages[batch->nr++] = page;
286	if (batch->nr == batch->max) {
287	if (!tlb_next_batch(tlb))
288	return 0;
289	batch = tlb->active;
290	}
291	VM_BUG_ON(batch->nr > batch->max);
292
293	return batch->max - batch->nr;
294	}
295
296	#endif /* HAVE_GENERIC_MMU_GATHER */
297
298	#ifdef CONFIG_HAVE_RCU_TABLE_FREE
299
300	/*
301	* See the comment near struct mmu_table_batch.
302	*/
303
304	static void tlb_remove_table_smp_sync(void *arg)
305	{
306	/* Simply deliver the interrupt */
307	}
308
309	static void tlb_remove_table_one(void *table)
310	{
311	/*
312	* This isn't an RCU grace period and hence the page-tables cannot be
313	* assumed to be actually RCU-freed.
314	*
315	* It is however sufficient for software page-table walkers that rely on
316	* IRQ disabling. See the comment near struct mmu_table_batch.
317	*/
318	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
319	__tlb_remove_table(table);
320	}
321
322	static void tlb_remove_table_rcu(struct rcu_head *head)
323	{
324	struct mmu_table_batch *batch;
325	int i;
326
327	batch = container_of(head, struct mmu_table_batch, rcu);
328
329	for (i = 0; i < batch->nr; i++)
330	__tlb_remove_table(batch->tables[i]);
331
332	free_page((unsigned long)batch);
333	}
334
335	void tlb_table_flush(struct mmu_gather *tlb)
336	{
337	struct mmu_table_batch **batch = &tlb->batch;
338
339	if (*batch) {
340	call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
341	*batch = NULL;
342	}
343	}
344
345	void tlb_remove_table(struct mmu_gather tlb, void table)
346	{
347	struct mmu_table_batch **batch = &tlb->batch;
348
349	tlb->need_flush = 1;
350
351	/*
352	* When there's less then two users of this mm there cannot be a
353	* concurrent page-table walk.
354	*/
355	if (atomic_read(&tlb->mm->mm_users) < 2) {
356	__tlb_remove_table(table);
357	return;
358	}
359
360	if (*batch == NULL) {
361	batch = (struct mmu_table_batch )__get_free_page(GFP_NOWAIT \| __GFP_NOWARN);
362	if (*batch == NULL) {
363	tlb_remove_table_one(table);
364	return;
365	}
366	(*batch)->nr = 0;
367	}
368	(batch)->tables[(batch)->nr++] = table;
369	if ((*batch)->nr == MAX_TABLE_BATCH)
370	tlb_table_flush(tlb);
371	}
372
373	#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
374
375	/*
376	* Note: this doesn't free the actual pages themselves. That
377	* has been handled earlier when unmapping all the memory regions.
378	*/
379	static void free_pte_range(struct mmu_gather tlb, pmd_t pmd,
380	unsigned long addr)
381	{
382	pgtable_t token = pmd_pgtable(*pmd);
383	pmd_clear(pmd);
384	pte_free_tlb(tlb, token, addr);
385	tlb->mm->nr_ptes--;
386	}
387
388	static inline void free_pmd_range(struct mmu_gather tlb, pud_t pud,
389	unsigned long addr, unsigned long end,
390	unsigned long floor, unsigned long ceiling)
391	{
392	pmd_t *pmd;
393	unsigned long next;
394	unsigned long start;
395
396	start = addr;
397	pmd = pmd_offset(pud, addr);
398	do {
399	next = pmd_addr_end(addr, end);
400	if (pmd_none_or_clear_bad(pmd))
401	continue;
402	free_pte_range(tlb, pmd, addr);
403	} while (pmd++, addr = next, addr != end);
404
405	start &= PUD_MASK;
406	if (start < floor)
407	return;
408	if (ceiling) {
409	ceiling &= PUD_MASK;
410	if (!ceiling)
411	return;
412	}
413	if (end - 1 > ceiling - 1)
414	return;
415
416	pmd = pmd_offset(pud, start);
417	pud_clear(pud);
418	pmd_free_tlb(tlb, pmd, start);
419	}
420
421	static inline void free_pud_range(struct mmu_gather tlb, pgd_t pgd,
422	unsigned long addr, unsigned long end,
423	unsigned long floor, unsigned long ceiling)
424	{
425	pud_t *pud;
426	unsigned long next;
427	unsigned long start;
428
429	start = addr;
430	pud = pud_offset(pgd, addr);
431	do {
432	next = pud_addr_end(addr, end);
433	if (pud_none_or_clear_bad(pud))
434	continue;
435	free_pmd_range(tlb, pud, addr, next, floor, ceiling);
436	} while (pud++, addr = next, addr != end);
437
438	start &= PGDIR_MASK;
439	if (start < floor)
440	return;
441	if (ceiling) {
442	ceiling &= PGDIR_MASK;
443	if (!ceiling)
444	return;
445	}
446	if (end - 1 > ceiling - 1)
447	return;
448
449	pud = pud_offset(pgd, start);
450	pgd_clear(pgd);
451	pud_free_tlb(tlb, pud, start);
452	}
453
454	/*
455	* This function frees user-level page tables of a process.
456	*
457	* Must be called with pagetable lock held.
458	*/
459	void free_pgd_range(struct mmu_gather *tlb,
460	unsigned long addr, unsigned long end,
461	unsigned long floor, unsigned long ceiling)
462	{
463	pgd_t *pgd;
464	unsigned long next;
465
466	/*
467	* The next few lines have given us lots of grief...
468	*
469	* Why are we testing PMD* at this top level? Because often
470	* there will be no work to do at all, and we'd prefer not to
471	* go all the way down to the bottom just to discover that.
472	*
473	* Why all these "- 1"s? Because 0 represents both the bottom
474	* of the address space and the top of it (using -1 for the
475	* top wouldn't help much: the masks would do the wrong thing).
476	* The rule is that addr 0 and floor 0 refer to the bottom of
477	* the address space, but end 0 and ceiling 0 refer to the top
478	* Comparisons need to use "end - 1" and "ceiling - 1" (though
479	* that end 0 case should be mythical).
480	*
481	* Wherever addr is brought up or ceiling brought down, we must
482	* be careful to reject "the opposite 0" before it confuses the
483	* subsequent tests. But what about where end is brought down
484	* by PMD_SIZE below? no, end can't go down to 0 there.
485	*
486	* Whereas we round start (addr) and ceiling down, by different
487	* masks at different levels, in order to test whether a table
488	* now has no other vmas using it, so can be freed, we don't
489	* bother to round floor or end up - the tests don't need that.
490	*/
491
492	addr &= PMD_MASK;
493	if (addr < floor) {
494	addr += PMD_SIZE;
495	if (!addr)
496	return;
497	}
498	if (ceiling) {
499	ceiling &= PMD_MASK;
500	if (!ceiling)
501	return;
502	}
503	if (end - 1 > ceiling - 1)
504	end -= PMD_SIZE;
505	if (addr > end - 1)
506	return;
507
508	pgd = pgd_offset(tlb->mm, addr);
509	do {
510	next = pgd_addr_end(addr, end);
511	if (pgd_none_or_clear_bad(pgd))
512	continue;
513	free_pud_range(tlb, pgd, addr, next, floor, ceiling);
514	} while (pgd++, addr = next, addr != end);
515	}
516
517	void free_pgtables(struct mmu_gather tlb, struct vm_area_struct vma,
518	unsigned long floor, unsigned long ceiling)
519	{
520	while (vma) {
521	struct vm_area_struct *next = vma->vm_next;
522	unsigned long addr = vma->vm_start;
523
524	/*
525	* Hide vma from rmap and truncate_pagecache before freeing
526	* pgtables
527	*/
528	unlink_anon_vmas(vma);
529	unlink_file_vma(vma);
530
531	if (is_vm_hugetlb_page(vma)) {
532	hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
533	floor, next? next->vm_start: ceiling);
534	} else {
535	/*
536	* Optimization: gather nearby vmas into one call down
537	*/
538	while (next && next->vm_start <= vma->vm_end + PMD_SIZE
539	&& !is_vm_hugetlb_page(next)) {
540	vma = next;
541	next = vma->vm_next;
542	unlink_anon_vmas(vma);
543	unlink_file_vma(vma);
544	}
545	free_pgd_range(tlb, addr, vma->vm_end,
546	floor, next? next->vm_start: ceiling);
547	}
548	vma = next;
549	}
550	}
551
552	int __pte_alloc(struct mm_struct mm, struct vm_area_struct vma,
553	pmd_t *pmd, unsigned long address)
554	{
555	pgtable_t new = pte_alloc_one(mm, address);
556	int wait_split_huge_page;
557	if (!new)
558	return -ENOMEM;
559
560	/*
561	* Ensure all pte setup (eg. pte page lock and page clearing) are
562	* visible before the pte is made visible to other CPUs by being
563	* put into page tables.
564	*
565	* The other side of the story is the pointer chasing in the page
566	* table walking code (when walking the page table without locking;
567	* ie. most of the time). Fortunately, these data accesses consist
568	* of a chain of data-dependent loads, meaning most CPUs (alpha
569	* being the notable exception) will already guarantee loads are
570	* seen in-order. See the alpha page table accessors for the
571	* smp_read_barrier_depends() barriers in page table walking code.
572	*/
573	smp_wmb(); /* Could be smp_wmb__xxx(before\|after)_spin_lock */
574
575	spin_lock(&mm->page_table_lock);
576	wait_split_huge_page = 0;
577	if (likely(pmd_none(pmd))) { / Has another populated it ? */
578	mm->nr_ptes++;
579	pmd_populate(mm, pmd, new);
580	new = NULL;
581	} else if (unlikely(pmd_trans_splitting(*pmd)))
582	wait_split_huge_page = 1;
583	spin_unlock(&mm->page_table_lock);
584	if (new)
585	pte_free(mm, new);
586	if (wait_split_huge_page)
587	wait_split_huge_page(vma->anon_vma, pmd);
588	return 0;
589	}
590
591	int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
592	{
593	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
594	if (!new)
595	return -ENOMEM;
596
597	smp_wmb(); /* See comment in __pte_alloc */
598
599	spin_lock(&init_mm.page_table_lock);
600	if (likely(pmd_none(pmd))) { / Has another populated it ? */
601	pmd_populate_kernel(&init_mm, pmd, new);
602	new = NULL;
603	} else
604	VM_BUG_ON(pmd_trans_splitting(*pmd));
605	spin_unlock(&init_mm.page_table_lock);
606	if (new)
607	pte_free_kernel(&init_mm, new);
608	return 0;
609	}
610
611	static inline void init_rss_vec(int *rss)
612	{
613	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
614	}
615
616	static inline void add_mm_rss_vec(struct mm_struct mm, int rss)
617	{
618	int i;
619
620	if (current->mm == mm)
621	sync_mm_rss(mm);
622	for (i = 0; i < NR_MM_COUNTERS; i++)
623	if (rss[i])
624	add_mm_counter(mm, i, rss[i]);
625	}
626
627	/*
628	* This function is called to print an error when a bad pte
629	* is found. For example, we might have a PFN-mapped pte in
630	* a region that doesn't allow it.
631	*
632	* The calling function must still handle the error.
633	*/
634	static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
635	pte_t pte, struct page *page)
636	{
637	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
638	pud_t *pud = pud_offset(pgd, addr);
639	pmd_t *pmd = pmd_offset(pud, addr);
640	struct address_space *mapping;
641	pgoff_t index;
642	static unsigned long resume;
643	static unsigned long nr_shown;
644	static unsigned long nr_unshown;
645
646	/*
647	* Allow a burst of 60 reports, then keep quiet for that minute;
648	* or allow a steady drip of one report per second.
649	*/
650	if (nr_shown == 60) {
651	if (time_before(jiffies, resume)) {
652	nr_unshown++;
653	return;
654	}
655	if (nr_unshown) {
656	printk(KERN_ALERT
657	"BUG: Bad page map: %lu messages suppressed\n",
658	nr_unshown);
659	nr_unshown = 0;
660	}
661	nr_shown = 0;
662	}
663	if (nr_shown++ == 0)
664	resume = jiffies + 60 * HZ;
665
666	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
667	index = linear_page_index(vma, addr);
668
669	printk(KERN_ALERT
670	"BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
671	current->comm,
672	(long long)pte_val(pte), (long long)pmd_val(*pmd));
673	if (page)
674	dump_page(page);
675	printk(KERN_ALERT
676	"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
677	(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
678	/*
679	* Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
680	*/
681	if (vma->vm_ops)
682	printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
683	vma->vm_ops->fault);
684	if (vma->vm_file && vma->vm_file->f_op)
685	printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
686	vma->vm_file->f_op->mmap);
687	dump_stack();
688	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
689	}
690
691	static inline bool is_cow_mapping(vm_flags_t flags)
692	{
693	return (flags & (VM_SHARED \| VM_MAYWRITE)) == VM_MAYWRITE;
694	}
695
696	/*
697	* vm_normal_page -- This function gets the "struct page" associated with a pte.
698	*
699	* "Special" mappings do not wish to be associated with a "struct page" (either
700	* it doesn't exist, or it exists but they don't want to touch it). In this
701	* case, NULL is returned here. "Normal" mappings do have a struct page.
702	*
703	* There are 2 broad cases. Firstly, an architecture may define a pte_special()
704	* pte bit, in which case this function is trivial. Secondly, an architecture
705	* may not have a spare pte bit, which requires a more complicated scheme,
706	* described below.
707	*
708	* A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
709	* special mapping (even if there are underlying and valid "struct pages").
710	* COWed pages of a VM_PFNMAP are always normal.
711	*
712	* The way we recognize COWed pages within VM_PFNMAP mappings is through the
713	* rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
714	* set, and the vm_pgoff will point to the first PFN mapped: thus every special
715	* mapping will always honor the rule
716	*
717	* pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
718	*
719	* And for normal mappings this is false.
720	*
721	* This restricts such mappings to be a linear translation from virtual address
722	* to pfn. To get around this restriction, we allow arbitrary mappings so long
723	* as the vma is not a COW mapping; in that case, we know that all ptes are
724	* special (because none can have been COWed).
725	*
726	*
727	* In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
728	*
729	* VM_MIXEDMAP mappings can likewise contain memory with or without "struct
730	* page" backing, however the difference is that _all_ pages with a struct
731	* page (that is, those where pfn_valid is true) are refcounted and considered
732	* normal pages by the VM. The disadvantage is that pages are refcounted
733	* (which can be slower and simply not an option for some PFNMAP users). The
734	* advantage is that we don't have to follow the strict linearity rule of
735	* PFNMAP mappings in order to support COWable mappings.
736	*
737	*/
738	#ifdef __HAVE_ARCH_PTE_SPECIAL
739	# define HAVE_PTE_SPECIAL 1
740	#else
741	# define HAVE_PTE_SPECIAL 0
742	#endif
743	struct page vm_normal_page(struct vm_area_struct vma, unsigned long addr,
744	pte_t pte)
745	{
746	unsigned long pfn = pte_pfn(pte);
747
748	if (HAVE_PTE_SPECIAL) {
749	if (likely(!pte_special(pte)))
750	goto check_pfn;
751	if (vma->vm_flags & (VM_PFNMAP \| VM_MIXEDMAP))
752	return NULL;
753	if (!is_zero_pfn(pfn))
754	print_bad_pte(vma, addr, pte, NULL);
755	return NULL;
756	}
757
758	/* !HAVE_PTE_SPECIAL case follows: */
759
760	if (unlikely(vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP))) {
761	if (vma->vm_flags & VM_MIXEDMAP) {
762	if (!pfn_valid(pfn))
763	return NULL;
764	goto out;
765	} else {
766	unsigned long off;
767	off = (addr - vma->vm_start) >> PAGE_SHIFT;
768	if (pfn == vma->vm_pgoff + off)
769	return NULL;
770	if (!is_cow_mapping(vma->vm_flags))
771	return NULL;
772	}
773	}
774
775	if (is_zero_pfn(pfn))
776	return NULL;
777	check_pfn:
778	if (unlikely(pfn > highest_memmap_pfn)) {
779	print_bad_pte(vma, addr, pte, NULL);
780	return NULL;
781	}
782
783	/*
784	* NOTE! We still have PageReserved() pages in the page tables.
785	* eg. VDSO mappings can cause them to exist.
786	*/
787	out:
788	return pfn_to_page(pfn);
789	}
790
791	/*
792	* copy one vm_area from one task to the other. Assumes the page tables
793	* already present in the new task to be cleared in the whole range
794	* covered by this vma.
795	*/
796
797	static inline unsigned long
798	copy_one_pte(struct mm_struct dst_mm, struct mm_struct src_mm,
799	pte_t dst_pte, pte_t src_pte, struct vm_area_struct *vma,
800	unsigned long addr, int *rss)
801	{
802	unsigned long vm_flags = vma->vm_flags;
803	pte_t pte = *src_pte;
804	struct page *page;
805
806	/* pte contains position in swap or file, so copy. */
807	if (unlikely(!pte_present(pte))) {
808	if (!pte_file(pte)) {
809	swp_entry_t entry = pte_to_swp_entry(pte);
810
811	if (swap_duplicate(entry) < 0)
812	return entry.val;
813
814	/* make sure dst_mm is on swapoff's mmlist. */
815	if (unlikely(list_empty(&dst_mm->mmlist))) {
816	spin_lock(&mmlist_lock);
817	if (list_empty(&dst_mm->mmlist))
818	list_add(&dst_mm->mmlist,
819	&src_mm->mmlist);
820	spin_unlock(&mmlist_lock);
821	}
822	if (likely(!non_swap_entry(entry)))
823	rss[MM_SWAPENTS]++;
824	else if (is_migration_entry(entry)) {
825	page = migration_entry_to_page(entry);
826
827	if (PageAnon(page))
828	rss[MM_ANONPAGES]++;
829	else
830	rss[MM_FILEPAGES]++;
831
832	if (is_write_migration_entry(entry) &&
833	is_cow_mapping(vm_flags)) {
834	/*
835	* COW mappings require pages in both
836	* parent and child to be set to read.
837	*/
838	make_migration_entry_read(&entry);
839	pte = swp_entry_to_pte(entry);
840	if (pte_swp_soft_dirty(*src_pte))
841	pte = pte_swp_mksoft_dirty(pte);
842	set_pte_at(src_mm, addr, src_pte, pte);
843	}
844	}
845	}
846	goto out_set_pte;
847	}
848
849	/*
850	* If it's a COW mapping, write protect it both
851	* in the parent and the child
852	*/
853	if (is_cow_mapping(vm_flags)) {
854	ptep_set_wrprotect(src_mm, addr, src_pte);
855	pte = pte_wrprotect(pte);
856	}
857
858	/*
859	* If it's a shared mapping, mark it clean in
860	* the child
861	*/
862	if (vm_flags & VM_SHARED)
863	pte = pte_mkclean(pte);
864	pte = pte_mkold(pte);
865
866	page = vm_normal_page(vma, addr, pte);
867	if (page) {
868	get_page(page);
869	page_dup_rmap(page);
870	if (PageAnon(page))
871	rss[MM_ANONPAGES]++;
872	else
873	rss[MM_FILEPAGES]++;
874	}
875
876	out_set_pte:
877	set_pte_at(dst_mm, addr, dst_pte, pte);
878	return 0;
879	}
880
881	int copy_pte_range(struct mm_struct dst_mm, struct mm_struct src_mm,
882	pmd_t dst_pmd, pmd_t src_pmd, struct vm_area_struct *vma,
883	unsigned long addr, unsigned long end)
884	{
885	pte_t orig_src_pte, orig_dst_pte;
886	pte_t src_pte, dst_pte;
887	spinlock_t src_ptl, dst_ptl;
888	int progress = 0;
889	int rss[NR_MM_COUNTERS];
890	swp_entry_t entry = (swp_entry_t){0};
891
892	again:
893	init_rss_vec(rss);
894
895	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
896	if (!dst_pte)
897	return -ENOMEM;
898	src_pte = pte_offset_map(src_pmd, addr);
899	src_ptl = pte_lockptr(src_mm, src_pmd);
900	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
901	orig_src_pte = src_pte;
902	orig_dst_pte = dst_pte;
903	arch_enter_lazy_mmu_mode();
904
905	do {
906	/*
907	* We are holding two locks at this point - either of them
908	* could generate latencies in another task on another CPU.
909	*/
910	if (progress >= 32) {
911	progress = 0;
912	if (need_resched() \|\|
913	spin_needbreak(src_ptl) \|\| spin_needbreak(dst_ptl))
914	break;
915	}
916	if (pte_none(*src_pte)) {
917	progress++;
918	continue;
919	}
920	entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
921	vma, addr, rss);
922	if (entry.val)
923	break;
924	progress += 8;
925	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
926
927	arch_leave_lazy_mmu_mode();
928	spin_unlock(src_ptl);
929	pte_unmap(orig_src_pte);
930	add_mm_rss_vec(dst_mm, rss);
931	pte_unmap_unlock(orig_dst_pte, dst_ptl);
932	cond_resched();
933
934	if (entry.val) {
935	if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
936	return -ENOMEM;
937	progress = 0;
938	}
939	if (addr != end)
940	goto again;
941	return 0;
942	}
943
944	static inline int copy_pmd_range(struct mm_struct dst_mm, struct mm_struct src_mm,
945	pud_t dst_pud, pud_t src_pud, struct vm_area_struct *vma,
946	unsigned long addr, unsigned long end)
947	{
948	pmd_t src_pmd, dst_pmd;
949	unsigned long next;
950
951	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
952	if (!dst_pmd)
953	return -ENOMEM;
954	src_pmd = pmd_offset(src_pud, addr);
955	do {
956	next = pmd_addr_end(addr, end);
957	if (pmd_trans_huge(*src_pmd)) {
958	int err;
959	VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
960	err = copy_huge_pmd(dst_mm, src_mm,
961	dst_pmd, src_pmd, addr, vma);
962	if (err == -ENOMEM)
963	return -ENOMEM;
964	if (!err)
965	continue;
966	/* fall through */
967	}
968	if (pmd_none_or_clear_bad(src_pmd))
969	continue;
970	if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
971	vma, addr, next))
972	return -ENOMEM;
973	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
974	return 0;
975	}
976
977	static inline int copy_pud_range(struct mm_struct dst_mm, struct mm_struct src_mm,
978	pgd_t dst_pgd, pgd_t src_pgd, struct vm_area_struct *vma,
979	unsigned long addr, unsigned long end)
980	{
981	pud_t src_pud, dst_pud;
982	unsigned long next;
983
984	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
985	if (!dst_pud)
986	return -ENOMEM;
987	src_pud = pud_offset(src_pgd, addr);
988	do {
989	next = pud_addr_end(addr, end);
990	if (pud_none_or_clear_bad(src_pud))
991	continue;
992	if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
993	vma, addr, next))
994	return -ENOMEM;
995	} while (dst_pud++, src_pud++, addr = next, addr != end);
996	return 0;
997	}
998
999	int copy_page_range(struct mm_struct dst_mm, struct mm_struct src_mm,
1000	struct vm_area_struct *vma)
1001	{
1002	pgd_t src_pgd, dst_pgd;
1003	unsigned long next;
1004	unsigned long addr = vma->vm_start;
1005	unsigned long end = vma->vm_end;
1006	unsigned long mmun_start; /* For mmu_notifiers */
1007	unsigned long mmun_end; /* For mmu_notifiers */
1008	bool is_cow;
1009	int ret;
1010
1011	/*
1012	* Don't copy ptes where a page fault will fill them correctly.
1013	* Fork becomes much lighter when there are big shared or private
1014	* readonly mappings. The tradeoff is that copy_page_range is more
1015	* efficient than faulting.
1016	*/
1017	if (!(vma->vm_flags & (VM_HUGETLB \| VM_NONLINEAR \|
1018	VM_PFNMAP \| VM_MIXEDMAP))) {
1019	if (!vma->anon_vma)
1020	return 0;
1021	}
1022
1023	if (is_vm_hugetlb_page(vma))
1024	return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1025
1026	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1027	/*
1028	* We do not free on error cases below as remove_vma
1029	* gets called on error from higher level routine
1030	*/
1031	ret = track_pfn_copy(vma);
1032	if (ret)
1033	return ret;
1034	}
1035
1036	/*
1037	* We need to invalidate the secondary MMU mappings only when
1038	* there could be a permission downgrade on the ptes of the
1039	* parent mm. And a permission downgrade will only happen if
1040	* is_cow_mapping() returns true.
1041	*/
1042	is_cow = is_cow_mapping(vma->vm_flags);
1043	mmun_start = addr;
1044	mmun_end = end;
1045	if (is_cow)
1046	mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1047	mmun_end);
1048
1049	ret = 0;
1050	dst_pgd = pgd_offset(dst_mm, addr);
1051	src_pgd = pgd_offset(src_mm, addr);
1052	do {
1053	next = pgd_addr_end(addr, end);
1054	if (pgd_none_or_clear_bad(src_pgd))
1055	continue;
1056	if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1057	vma, addr, next))) {
1058	ret = -ENOMEM;
1059	break;
1060	}
1061	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
1062
1063	if (is_cow)
1064	mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1065	return ret;
1066	}
1067
1068	static unsigned long zap_pte_range(struct mmu_gather *tlb,
1069	struct vm_area_struct vma, pmd_t pmd,
1070	unsigned long addr, unsigned long end,
1071	struct zap_details *details)
1072	{
1073	struct mm_struct *mm = tlb->mm;
1074	int force_flush = 0;
1075	int rss[NR_MM_COUNTERS];
1076	spinlock_t *ptl;
1077	pte_t *start_pte;
1078	pte_t *pte;
1079
1080	again:
1081	init_rss_vec(rss);
1082	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1083	pte = start_pte;
1084	arch_enter_lazy_mmu_mode();
1085	do {
1086	pte_t ptent = *pte;
1087	if (pte_none(ptent)) {
1088	continue;
1089	}
1090
1091	if (pte_present(ptent)) {
1092	struct page *page;
1093
1094	page = vm_normal_page(vma, addr, ptent);
1095	if (unlikely(details) && page) {
1096	/*
1097	* unmap_shared_mapping_pages() wants to
1098	* invalidate cache without truncating:
1099	* unmap shared but keep private pages.
1100	*/
1101	if (details->check_mapping &&
1102	details->check_mapping != page->mapping)
1103	continue;
1104	/*
1105	* Each page->index must be checked when
1106	* invalidating or truncating nonlinear.
1107	*/
1108	if (details->nonlinear_vma &&
1109	(page->index < details->first_index \|\|
1110	page->index > details->last_index))
1111	continue;
1112	}
1113	ptent = ptep_get_and_clear_full(mm, addr, pte,
1114	tlb->fullmm);
1115	tlb_remove_tlb_entry(tlb, pte, addr);
1116	if (unlikely(!page))
1117	continue;
1118	if (unlikely(details) && details->nonlinear_vma
1119	&& linear_page_index(details->nonlinear_vma,
1120	addr) != page->index) {
1121	pte_t ptfile = pgoff_to_pte(page->index);
1122	if (pte_soft_dirty(ptent))
1123	pte_file_mksoft_dirty(ptfile);
1124	set_pte_at(mm, addr, pte, ptfile);
1125	}
1126	if (PageAnon(page))
1127	rss[MM_ANONPAGES]--;
1128	else {
1129	if (pte_dirty(ptent))
1130	set_page_dirty(page);
1131	if (pte_young(ptent) &&
1132	likely(!(vma->vm_flags & VM_SEQ_READ)))
1133	mark_page_accessed(page);
1134	rss[MM_FILEPAGES]--;
1135	}
1136	page_remove_rmap(page);
1137	if (unlikely(page_mapcount(page) < 0))
1138	print_bad_pte(vma, addr, ptent, page);
1139	force_flush = !__tlb_remove_page(tlb, page);
1140	if (force_flush)
1141	break;
1142	continue;
1143	}
1144	/*
1145	* If details->check_mapping, we leave swap entries;
1146	* if details->nonlinear_vma, we leave file entries.
1147	*/
1148	if (unlikely(details))
1149	continue;
1150	if (pte_file(ptent)) {
1151	if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1152	print_bad_pte(vma, addr, ptent, NULL);
1153	} else {
1154	swp_entry_t entry = pte_to_swp_entry(ptent);
1155
1156	if (!non_swap_entry(entry))
1157	rss[MM_SWAPENTS]--;
1158	else if (is_migration_entry(entry)) {
1159	struct page *page;
1160
1161	page = migration_entry_to_page(entry);
1162
1163	if (PageAnon(page))
1164	rss[MM_ANONPAGES]--;
1165	else
1166	rss[MM_FILEPAGES]--;
1167	}
1168	if (unlikely(!free_swap_and_cache(entry)))
1169	print_bad_pte(vma, addr, ptent, NULL);
1170	}
1171	pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1172	} while (pte++, addr += PAGE_SIZE, addr != end);
1173
1174	add_mm_rss_vec(mm, rss);
1175	arch_leave_lazy_mmu_mode();
1176	pte_unmap_unlock(start_pte, ptl);
1177
1178	/*
1179	* mmu_gather ran out of room to batch pages, we break out of
1180	* the PTE lock to avoid doing the potential expensive TLB invalidate
1181	* and page-free while holding it.
1182	*/
1183	if (force_flush) {
1184	unsigned long old_end;
1185
1186	force_flush = 0;
1187
1188	/*
1189	* Flush the TLB just for the previous segment,
1190	* then update the range to be the remaining
1191	* TLB range.
1192	*/
1193	old_end = tlb->end;
1194	tlb->end = addr;
1195
1196	tlb_flush_mmu(tlb);
1197
1198	tlb->start = addr;
1199	tlb->end = old_end;
1200
1201	if (addr != end)
1202	goto again;
1203	}
1204
1205	return addr;
1206	}
1207
1208	static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1209	struct vm_area_struct vma, pud_t pud,
1210	unsigned long addr, unsigned long end,
1211	struct zap_details *details)
1212	{
1213	pmd_t *pmd;
1214	unsigned long next;
1215
1216	pmd = pmd_offset(pud, addr);
1217	do {
1218	next = pmd_addr_end(addr, end);
1219	if (pmd_trans_huge(*pmd)) {
1220	if (next - addr != HPAGE_PMD_SIZE) {
1221	#ifdef CONFIG_DEBUG_VM
1222	if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
1223	pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
1224	__func__, addr, end,
1225	vma->vm_start,
1226	vma->vm_end);
1227	BUG();
1228	}
1229	#endif
1230	split_huge_page_pmd(vma, addr, pmd);
1231	} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1232	goto next;
1233	/* fall through */
1234	}
1235	/*
1236	* Here there can be other concurrent MADV_DONTNEED or
1237	* trans huge page faults running, and if the pmd is
1238	* none or trans huge it can change under us. This is
1239	* because MADV_DONTNEED holds the mmap_sem in read
1240	* mode.
1241	*/
1242	if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1243	goto next;
1244	next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1245	next:
1246	cond_resched();
1247	} while (pmd++, addr = next, addr != end);
1248
1249	return addr;
1250	}
1251
1252	static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1253	struct vm_area_struct vma, pgd_t pgd,
1254	unsigned long addr, unsigned long end,
1255	struct zap_details *details)
1256	{
1257	pud_t *pud;
1258	unsigned long next;
1259
1260	pud = pud_offset(pgd, addr);
1261	do {
1262	next = pud_addr_end(addr, end);
1263	if (pud_none_or_clear_bad(pud))
1264	continue;
1265	next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1266	} while (pud++, addr = next, addr != end);
1267
1268	return addr;
1269	}
1270
1271	static void unmap_page_range(struct mmu_gather *tlb,
1272	struct vm_area_struct *vma,
1273	unsigned long addr, unsigned long end,
1274	struct zap_details *details)
1275	{
1276	pgd_t *pgd;
1277	unsigned long next;
1278
1279	if (details && !details->check_mapping && !details->nonlinear_vma)
1280	details = NULL;
1281
1282	BUG_ON(addr >= end);
1283	mem_cgroup_uncharge_start();
1284	tlb_start_vma(tlb, vma);
1285	pgd = pgd_offset(vma->vm_mm, addr);
1286	do {
1287	next = pgd_addr_end(addr, end);
1288	if (pgd_none_or_clear_bad(pgd))
1289	continue;
1290	next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1291	} while (pgd++, addr = next, addr != end);
1292	tlb_end_vma(tlb, vma);
1293	mem_cgroup_uncharge_end();
1294	}
1295
1296
1297	static void unmap_single_vma(struct mmu_gather *tlb,
1298	struct vm_area_struct *vma, unsigned long start_addr,
1299	unsigned long end_addr,
1300	struct zap_details *details)
1301	{
1302	unsigned long start = max(vma->vm_start, start_addr);
1303	unsigned long end;
1304
1305	if (start >= vma->vm_end)
1306	return;
1307	end = min(vma->vm_end, end_addr);
1308	if (end <= vma->vm_start)
1309	return;
1310
1311	if (vma->vm_file)
1312	uprobe_munmap(vma, start, end);
1313
1314	if (unlikely(vma->vm_flags & VM_PFNMAP))
1315	untrack_pfn(vma, 0, 0);
1316
1317	if (start != end) {
1318	if (unlikely(is_vm_hugetlb_page(vma))) {
1319	/*
1320	* It is undesirable to test vma->vm_file as it
1321	* should be non-null for valid hugetlb area.
1322	* However, vm_file will be NULL in the error
1323	* cleanup path of do_mmap_pgoff. When
1324	* hugetlbfs ->mmap method fails,
1325	* do_mmap_pgoff() nullifies vma->vm_file
1326	* before calling this function to clean up.
1327	* Since no pte has actually been setup, it is
1328	* safe to do nothing in this case.
1329	*/
1330	if (vma->vm_file) {
1331	mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
1332	__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1333	mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
1334	}
1335	} else
1336	unmap_page_range(tlb, vma, start, end, details);
1337	}
1338	}
1339
1340	/**
1341	* unmap_vmas - unmap a range of memory covered by a list of vma's
1342	* @tlb: address of the caller's struct mmu_gather
1343	* @vma: the starting vma
1344	* @start_addr: virtual address at which to start unmapping
1345	* @end_addr: virtual address at which to end unmapping
1346	*
1347	* Unmap all pages in the vma list.
1348	*
1349	* Only addresses between `start' and `end' will be unmapped.
1350	*
1351	* The VMA list must be sorted in ascending virtual address order.
1352	*
1353	* unmap_vmas() assumes that the caller will flush the whole unmapped address
1354	* range after unmap_vmas() returns. So the only responsibility here is to
1355	* ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1356	* drops the lock and schedules.
1357	*/
1358	void unmap_vmas(struct mmu_gather *tlb,
1359	struct vm_area_struct *vma, unsigned long start_addr,
1360	unsigned long end_addr)
1361	{
1362	struct mm_struct *mm = vma->vm_mm;
1363
1364	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1365	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1366	unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1367	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1368	}
1369
1370	/**
1371	* zap_page_range - remove user pages in a given range
1372	* @vma: vm_area_struct holding the applicable pages
1373	* @start: starting address of pages to zap
1374	* @size: number of bytes to zap
1375	* @details: details of nonlinear truncation or shared cache invalidation
1376	*
1377	* Caller must protect the VMA list
1378	*/
1379	void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1380	unsigned long size, struct zap_details *details)
1381	{
1382	struct mm_struct *mm = vma->vm_mm;
1383	struct mmu_gather tlb;
1384	unsigned long end = start + size;
1385
1386	lru_add_drain();
1387	tlb_gather_mmu(&tlb, mm, start, end);
1388	update_hiwater_rss(mm);
1389	mmu_notifier_invalidate_range_start(mm, start, end);
1390	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1391	unmap_single_vma(&tlb, vma, start, end, details);
1392	mmu_notifier_invalidate_range_end(mm, start, end);
1393	tlb_finish_mmu(&tlb, start, end);
1394	}
1395
1396	/**
1397	* zap_page_range_single - remove user pages in a given range
1398	* @vma: vm_area_struct holding the applicable pages
1399	* @address: starting address of pages to zap
1400	* @size: number of bytes to zap
1401	* @details: details of nonlinear truncation or shared cache invalidation
1402	*
1403	* The range must fit into one VMA.
1404	*/
1405	static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1406	unsigned long size, struct zap_details *details)
1407	{
1408	struct mm_struct *mm = vma->vm_mm;
1409	struct mmu_gather tlb;
1410	unsigned long end = address + size;
1411
1412	lru_add_drain();
1413	tlb_gather_mmu(&tlb, mm, address, end);
1414	update_hiwater_rss(mm);
1415	mmu_notifier_invalidate_range_start(mm, address, end);
1416	unmap_single_vma(&tlb, vma, address, end, details);
1417	mmu_notifier_invalidate_range_end(mm, address, end);
1418	tlb_finish_mmu(&tlb, address, end);
1419	}
1420
1421	/**
1422	* zap_vma_ptes - remove ptes mapping the vma
1423	* @vma: vm_area_struct holding ptes to be zapped
1424	* @address: starting address of pages to zap
1425	* @size: number of bytes to zap
1426	*
1427	* This function only unmaps ptes assigned to VM_PFNMAP vmas.
1428	*
1429	* The entire address range must be fully contained within the vma.
1430	*
1431	* Returns 0 if successful.
1432	*/
1433	int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1434	unsigned long size)
1435	{
1436	if (address < vma->vm_start \|\| address + size > vma->vm_end \|\|
1437	!(vma->vm_flags & VM_PFNMAP))
1438	return -1;
1439	zap_page_range_single(vma, address, size, NULL);
1440	return 0;
1441	}
1442	EXPORT_SYMBOL_GPL(zap_vma_ptes);
1443
1444	/**
1445	* follow_page_mask - look up a page descriptor from a user-virtual address
1446	* @vma: vm_area_struct mapping @address
1447	* @address: virtual address to look up
1448	* @flags: flags modifying lookup behaviour
1449	* @page_mask: on output, *page_mask is set according to the size of the page
1450	*
1451	* @flags can have FOLL_ flags set, defined in <linux/mm.h>
1452	*
1453	* Returns the mapped (struct page *), %NULL if no mapping exists, or
1454	* an error pointer if there is a mapping to something not represented
1455	* by a page descriptor (see also vm_normal_page()).
1456	*/
1457	struct page follow_page_mask(struct vm_area_struct vma,
1458	unsigned long address, unsigned int flags,
1459	unsigned int *page_mask)
1460	{
1461	pgd_t *pgd;
1462	pud_t *pud;
1463	pmd_t *pmd;
1464	pte_t *ptep, pte;
1465	spinlock_t *ptl;
1466	struct page *page;
1467	struct mm_struct *mm = vma->vm_mm;
1468
1469	*page_mask = 0;
1470
1471	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1472	if (!IS_ERR(page)) {
1473	BUG_ON(flags & FOLL_GET);
1474	goto out;
1475	}
1476
1477	page = NULL;
1478	pgd = pgd_offset(mm, address);
1479	if (pgd_none(pgd) \|\| unlikely(pgd_bad(pgd)))
1480	goto no_page_table;
1481
1482	pud = pud_offset(pgd, address);
1483	if (pud_none(*pud))
1484	goto no_page_table;
1485	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1486	if (flags & FOLL_GET)
1487	goto out;
1488	page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1489	goto out;
1490	}
1491	if (unlikely(pud_bad(*pud)))
1492	goto no_page_table;
1493
1494	pmd = pmd_offset(pud, address);
1495	if (pmd_none(*pmd))
1496	goto no_page_table;
1497	if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1498	page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1499	if (flags & FOLL_GET) {
1500	/*
1501	* Refcount on tail pages are not well-defined and
1502	* shouldn't be taken. The caller should handle a NULL
1503	* return when trying to follow tail pages.
1504	*/
1505	if (PageHead(page))
1506	get_page(page);
1507	else {
1508	page = NULL;
1509	goto out;
1510	}
1511	}
1512	goto out;
1513	}
1514	if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
1515	goto no_page_table;
1516	if (pmd_trans_huge(*pmd)) {
1517	if (flags & FOLL_SPLIT) {
1518	split_huge_page_pmd(vma, address, pmd);
1519	goto split_fallthrough;
1520	}
1521	spin_lock(&mm->page_table_lock);
1522	if (likely(pmd_trans_huge(*pmd))) {
1523	if (unlikely(pmd_trans_splitting(*pmd))) {
1524	spin_unlock(&mm->page_table_lock);
1525	wait_split_huge_page(vma->anon_vma, pmd);
1526	} else {
1527	page = follow_trans_huge_pmd(vma, address,
1528	pmd, flags);
1529	spin_unlock(&mm->page_table_lock);
1530	*page_mask = HPAGE_PMD_NR - 1;
1531	goto out;
1532	}
1533	} else
1534	spin_unlock(&mm->page_table_lock);
1535	/* fall through */
1536	}
1537	split_fallthrough:
1538	if (unlikely(pmd_bad(*pmd)))
1539	goto no_page_table;
1540
1541	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1542
1543	pte = *ptep;
1544	if (!pte_present(pte)) {
1545	swp_entry_t entry;
1546	/*
1547	* KSM's break_ksm() relies upon recognizing a ksm page
1548	* even while it is being migrated, so for that case we
1549	* need migration_entry_wait().
1550	*/
1551	if (likely(!(flags & FOLL_MIGRATION)))
1552	goto no_page;
1553	if (pte_none(pte) \|\| pte_file(pte))
1554	goto no_page;
1555	entry = pte_to_swp_entry(pte);
1556	if (!is_migration_entry(entry))
1557	goto no_page;
1558	pte_unmap_unlock(ptep, ptl);
1559	migration_entry_wait(mm, pmd, address);
1560	goto split_fallthrough;
1561	}
1562	if ((flags & FOLL_NUMA) && pte_numa(pte))
1563	goto no_page;
1564	if ((flags & FOLL_WRITE) && !pte_write(pte))
1565	goto unlock;
1566
1567	page = vm_normal_page(vma, address, pte);
1568	if (unlikely(!page)) {
1569	if ((flags & FOLL_DUMP) \|\|
1570	!is_zero_pfn(pte_pfn(pte)))
1571	goto bad_page;
1572	page = pte_page(pte);
1573	}
1574
1575	if (flags & FOLL_GET)
1576	get_page_foll(page);
1577	if (flags & FOLL_TOUCH) {
1578	if ((flags & FOLL_WRITE) &&
1579	!pte_dirty(pte) && !PageDirty(page))
1580	set_page_dirty(page);
1581	/*
1582	* pte_mkyoung() would be more correct here, but atomic care
1583	* is needed to avoid losing the dirty bit: it is easier to use
1584	* mark_page_accessed().
1585	*/
1586	mark_page_accessed(page);
1587	}
1588	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1589	/*
1590	* The preliminary mapping check is mainly to avoid the
1591	* pointless overhead of lock_page on the ZERO_PAGE
1592	* which might bounce very badly if there is contention.
1593	*
1594	* If the page is already locked, we don't need to
1595	* handle it now - vmscan will handle it later if and
1596	* when it attempts to reclaim the page.
1597	*/
1598	if (page->mapping && trylock_page(page)) {
1599	lru_add_drain(); /* push cached pages to LRU */
1600	/*
1601	* Because we lock page here, and migration is
1602	* blocked by the pte's page reference, and we
1603	* know the page is still mapped, we don't even
1604	* need to check for file-cache page truncation.
1605	*/
1606	mlock_vma_page(page);
1607	unlock_page(page);
1608	}
1609	}
1610	unlock:
1611	pte_unmap_unlock(ptep, ptl);
1612	out:
1613	return page;
1614
1615	bad_page:
1616	pte_unmap_unlock(ptep, ptl);
1617	return ERR_PTR(-EFAULT);
1618
1619	no_page:
1620	pte_unmap_unlock(ptep, ptl);
1621	if (!pte_none(pte))
1622	return page;
1623
1624	no_page_table:
1625	/*
1626	* When core dumping an enormous anonymous area that nobody
1627	* has touched so far, we don't want to allocate unnecessary pages or
1628	* page tables. Return error instead of NULL to skip handle_mm_fault,
1629	* then get_dump_page() will return NULL to leave a hole in the dump.
1630	* But we can only make this optimization where a hole would surely
1631	* be zero-filled if handle_mm_fault() actually did handle it.
1632	*/
1633	if ((flags & FOLL_DUMP) &&
1634	(!vma->vm_ops \|\| !vma->vm_ops->fault))
1635	return ERR_PTR(-EFAULT);
1636	return page;
1637	}
1638
1639	static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1640	{
1641	return stack_guard_page_start(vma, addr) \|\|
1642	stack_guard_page_end(vma, addr+PAGE_SIZE);
1643	}
1644
1645	/**
1646	* __get_user_pages() - pin user pages in memory
1647	* @tsk: task_struct of target task
1648	* @mm: mm_struct of target mm
1649	* @start: starting user address
1650	* @nr_pages: number of pages from start to pin
1651	* @gup_flags: flags modifying pin behaviour
1652	* @pages: array that receives pointers to the pages pinned.
1653	* Should be at least nr_pages long. Or NULL, if caller
1654	* only intends to ensure the pages are faulted in.
1655	* @vmas: array of pointers to vmas corresponding to each page.
1656	* Or NULL if the caller does not require them.
1657	* @nonblocking: whether waiting for disk IO or mmap_sem contention
1658	*
1659	* Returns number of pages pinned. This may be fewer than the number
1660	* requested. If nr_pages is 0 or negative, returns 0. If no pages
1661	* were pinned, returns -errno. Each page returned must be released
1662	* with a put_page() call when it is finished with. vmas will only
1663	* remain valid while mmap_sem is held.
1664	*
1665	* Must be called with mmap_sem held for read or write.
1666	*
1667	* __get_user_pages walks a process's page tables and takes a reference to
1668	* each struct page that each user address corresponds to at a given
1669	* instant. That is, it takes the page that would be accessed if a user
1670	* thread accesses the given user virtual address at that instant.
1671	*
1672	* This does not guarantee that the page exists in the user mappings when
1673	* __get_user_pages returns, and there may even be a completely different
1674	* page there in some cases (eg. if mmapped pagecache has been invalidated
1675	* and subsequently re faulted). However it does guarantee that the page
1676	* won't be freed completely. And mostly callers simply care that the page
1677	* contains data that was valid at some point in time. Typically, an IO
1678	* or similar operation cannot guarantee anything stronger anyway because
1679	* locks can't be held over the syscall boundary.
1680	*
1681	* If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1682	* the page is written to, set_page_dirty (or set_page_dirty_lock, as
1683	* appropriate) must be called after the page is finished with, and
1684	* before put_page is called.
1685	*
1686	* If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1687	* or mmap_sem contention, and if waiting is needed to pin all pages,
1688	* *@nonblocking will be set to 0.
1689	*
1690	* In most cases, get_user_pages or get_user_pages_fast should be used
1691	* instead of __get_user_pages. __get_user_pages should be used only if
1692	* you need some special @gup_flags.
1693	*/
1694	long __get_user_pages(struct task_struct tsk, struct mm_struct mm,
1695	unsigned long start, unsigned long nr_pages,
1696	unsigned int gup_flags, struct page **pages,
1697	struct vm_area_struct *vmas, int nonblocking)
1698	{
1699	long i;
1700	unsigned long vm_flags;
1701	unsigned int page_mask;
1702
1703	if (!nr_pages)
1704	return 0;
1705
1706	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1707
1708	/*
1709	* Require read or write permissions.
1710	* If FOLL_FORCE is set, we only require the "MAY" flags.
1711	*/
1712	vm_flags = (gup_flags & FOLL_WRITE) ?
1713	(VM_WRITE \| VM_MAYWRITE) : (VM_READ \| VM_MAYREAD);
1714	vm_flags &= (gup_flags & FOLL_FORCE) ?
1715	(VM_MAYREAD \| VM_MAYWRITE) : (VM_READ \| VM_WRITE);
1716
1717	/*
1718	* If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault
1719	* would be called on PROT_NONE ranges. We must never invoke
1720	* handle_mm_fault on PROT_NONE ranges or the NUMA hinting
1721	* page faults would unprotect the PROT_NONE ranges if
1722	* _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd
1723	* bitflag. So to avoid that, don't set FOLL_NUMA if
1724	* FOLL_FORCE is set.
1725	*/
1726	if (!(gup_flags & FOLL_FORCE))
1727	gup_flags \|= FOLL_NUMA;
1728
1729	i = 0;
1730
1731	do {
1732	struct vm_area_struct *vma;
1733
1734	vma = find_extend_vma(mm, start);
1735	if (!vma && in_gate_area(mm, start)) {
1736	unsigned long pg = start & PAGE_MASK;
1737	pgd_t *pgd;
1738	pud_t *pud;
1739	pmd_t *pmd;
1740	pte_t *pte;
1741
1742	/* user gate pages are read-only */
1743	if (gup_flags & FOLL_WRITE)
1744	return i ? : -EFAULT;
1745	if (pg > TASK_SIZE)
1746	pgd = pgd_offset_k(pg);
1747	else
1748	pgd = pgd_offset_gate(mm, pg);
1749	BUG_ON(pgd_none(*pgd));
1750	pud = pud_offset(pgd, pg);
1751	BUG_ON(pud_none(*pud));
1752	pmd = pmd_offset(pud, pg);
1753	if (pmd_none(*pmd))
1754	return i ? : -EFAULT;
1755	VM_BUG_ON(pmd_trans_huge(*pmd));
1756	pte = pte_offset_map(pmd, pg);
1757	if (pte_none(*pte)) {
1758	pte_unmap(pte);
1759	return i ? : -EFAULT;
1760	}
1761	vma = get_gate_vma(mm);
1762	if (pages) {
1763	struct page *page;
1764
1765	page = vm_normal_page(vma, start, *pte);
1766	if (!page) {
1767	if (!(gup_flags & FOLL_DUMP) &&
1768	is_zero_pfn(pte_pfn(*pte)))
1769	page = pte_page(*pte);
1770	else {
1771	pte_unmap(pte);
1772	return i ? : -EFAULT;
1773	}
1774	}
1775	pages[i] = page;
1776	get_page(page);
1777	}
1778	pte_unmap(pte);
1779	page_mask = 0;
1780	goto next_page;
1781	}
1782
1783	if (!vma \|\|
1784	(vma->vm_flags & (VM_IO \| VM_PFNMAP)) \|\|
1785	!(vm_flags & vma->vm_flags))
1786	return i ? : -EFAULT;
1787
1788	if (is_vm_hugetlb_page(vma)) {
1789	i = follow_hugetlb_page(mm, vma, pages, vmas,
1790	&start, &nr_pages, i, gup_flags);
1791	continue;
1792	}
1793
1794	do {
1795	struct page *page;
1796	unsigned int foll_flags = gup_flags;
1797	unsigned int page_increm;
1798
1799	/*
1800	* If we have a pending SIGKILL, don't keep faulting
1801	* pages and potentially allocating memory.
1802	*/
1803	if (unlikely(fatal_signal_pending(current)))
1804	return i ? i : -ERESTARTSYS;
1805
1806	cond_resched();
1807	while (!(page = follow_page_mask(vma, start,
1808	foll_flags, &page_mask))) {
1809	int ret;
1810	unsigned int fault_flags = 0;
1811
1812	/* For mlock, just skip the stack guard page. */
1813	if (foll_flags & FOLL_MLOCK) {
1814	if (stack_guard_page(vma, start))
1815	goto next_page;
1816	}
1817	if (foll_flags & FOLL_WRITE)
1818	fault_flags \|= FAULT_FLAG_WRITE;
1819	if (nonblocking)
1820	fault_flags \|= FAULT_FLAG_ALLOW_RETRY;
1821	if (foll_flags & FOLL_NOWAIT)
1822	fault_flags \|= (FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_RETRY_NOWAIT);
1823
1824	ret = handle_mm_fault(mm, vma, start,
1825	fault_flags);
1826
1827	if (ret & VM_FAULT_ERROR) {
1828	if (ret & VM_FAULT_OOM)
1829	return i ? i : -ENOMEM;
1830	if (ret & (VM_FAULT_HWPOISON \|
1831	VM_FAULT_HWPOISON_LARGE)) {
1832	if (i)
1833	return i;
1834	else if (gup_flags & FOLL_HWPOISON)
1835	return -EHWPOISON;
1836	else
1837	return -EFAULT;
1838	}
1839	if (ret & VM_FAULT_SIGBUS)
1840	return i ? i : -EFAULT;
1841	BUG();
1842	}
1843
1844	if (tsk) {
1845	if (ret & VM_FAULT_MAJOR)
1846	tsk->maj_flt++;
1847	else
1848	tsk->min_flt++;
1849	}
1850
1851	if (ret & VM_FAULT_RETRY) {
1852	if (nonblocking)
1853	*nonblocking = 0;
1854	return i;
1855	}
1856
1857	/*
1858	* The VM_FAULT_WRITE bit tells us that
1859	* do_wp_page has broken COW when necessary,
1860	* even if maybe_mkwrite decided not to set
1861	* pte_write. We can thus safely do subsequent
1862	* page lookups as if they were reads. But only
1863	* do so when looping for pte_write is futile:
1864	* in some cases userspace may also be wanting
1865	* to write to the gotten user page, which a
1866	* read fault here might prevent (a readonly
1867	* page might get reCOWed by userspace write).
1868	*/
1869	if ((ret & VM_FAULT_WRITE) &&
1870	!(vma->vm_flags & VM_WRITE))
1871	foll_flags &= ~FOLL_WRITE;
1872
1873	cond_resched();
1874	}
1875	if (IS_ERR(page))
1876	return i ? i : PTR_ERR(page);
1877	if (pages) {
1878	pages[i] = page;
1879
1880	flush_anon_page(vma, page, start);
1881	flush_dcache_page(page);
1882	page_mask = 0;
1883	}
1884	next_page:
1885	if (vmas) {
1886	vmas[i] = vma;
1887	page_mask = 0;
1888	}
1889	page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
1890	if (page_increm > nr_pages)
1891	page_increm = nr_pages;
1892	i += page_increm;
1893	start += page_increm * PAGE_SIZE;
1894	nr_pages -= page_increm;
1895	} while (nr_pages && start < vma->vm_end);
1896	} while (nr_pages);
1897	return i;
1898	}
1899	EXPORT_SYMBOL(__get_user_pages);
1900
1901	/*
1902	* fixup_user_fault() - manually resolve a user page fault
1903	* @tsk: the task_struct to use for page fault accounting, or
1904	* NULL if faults are not to be recorded.
1905	* @mm: mm_struct of target mm
1906	* @address: user address
1907	* @fault_flags:flags to pass down to handle_mm_fault()
1908	*
1909	* This is meant to be called in the specific scenario where for locking reasons
1910	* we try to access user memory in atomic context (within a pagefault_disable()
1911	* section), this returns -EFAULT, and we want to resolve the user fault before
1912	* trying again.
1913	*
1914	* Typically this is meant to be used by the futex code.
1915	*
1916	* The main difference with get_user_pages() is that this function will
1917	* unconditionally call handle_mm_fault() which will in turn perform all the
1918	* necessary SW fixup of the dirty and young bits in the PTE, while
1919	* handle_mm_fault() only guarantees to update these in the struct page.
1920	*
1921	* This is important for some architectures where those bits also gate the
1922	* access permission to the page because they are maintained in software. On
1923	* such architectures, gup() will not be enough to make a subsequent access
1924	* succeed.
1925	*
1926	* This should be called with the mm_sem held for read.
1927	*/
1928	int fixup_user_fault(struct task_struct tsk, struct mm_struct mm,
1929	unsigned long address, unsigned int fault_flags)
1930	{
1931	struct vm_area_struct *vma;
1932	int ret;
1933
1934	vma = find_extend_vma(mm, address);
1935	if (!vma \|\| address < vma->vm_start)
1936	return -EFAULT;
1937
1938	ret = handle_mm_fault(mm, vma, address, fault_flags);
1939	if (ret & VM_FAULT_ERROR) {
1940	if (ret & VM_FAULT_OOM)
1941	return -ENOMEM;
1942	if (ret & (VM_FAULT_HWPOISON \| VM_FAULT_HWPOISON_LARGE))
1943	return -EHWPOISON;
1944	if (ret & VM_FAULT_SIGBUS)
1945	return -EFAULT;
1946	BUG();
1947	}
1948	if (tsk) {
1949	if (ret & VM_FAULT_MAJOR)
1950	tsk->maj_flt++;
1951	else
1952	tsk->min_flt++;
1953	}
1954	return 0;
1955	}
1956
1957	/*
1958	* get_user_pages() - pin user pages in memory
1959	* @tsk: the task_struct to use for page fault accounting, or
1960	* NULL if faults are not to be recorded.
1961	* @mm: mm_struct of target mm
1962	* @start: starting user address
1963	* @nr_pages: number of pages from start to pin
1964	* @write: whether pages will be written to by the caller
1965	* @force: whether to force write access even if user mapping is
1966	* readonly. This will result in the page being COWed even
1967	* in MAP_SHARED mappings. You do not want this.
1968	* @pages: array that receives pointers to the pages pinned.
1969	* Should be at least nr_pages long. Or NULL, if caller
1970	* only intends to ensure the pages are faulted in.
1971	* @vmas: array of pointers to vmas corresponding to each page.
1972	* Or NULL if the caller does not require them.
1973	*
1974	* Returns number of pages pinned. This may be fewer than the number
1975	* requested. If nr_pages is 0 or negative, returns 0. If no pages
1976	* were pinned, returns -errno. Each page returned must be released
1977	* with a put_page() call when it is finished with. vmas will only
1978	* remain valid while mmap_sem is held.
1979	*
1980	* Must be called with mmap_sem held for read or write.
1981	*
1982	* get_user_pages walks a process's page tables and takes a reference to
1983	* each struct page that each user address corresponds to at a given
1984	* instant. That is, it takes the page that would be accessed if a user
1985	* thread accesses the given user virtual address at that instant.
1986	*
1987	* This does not guarantee that the page exists in the user mappings when
1988	* get_user_pages returns, and there may even be a completely different
1989	* page there in some cases (eg. if mmapped pagecache has been invalidated
1990	* and subsequently re faulted). However it does guarantee that the page
1991	* won't be freed completely. And mostly callers simply care that the page
1992	* contains data that was valid at some point in time. Typically, an IO
1993	* or similar operation cannot guarantee anything stronger anyway because
1994	* locks can't be held over the syscall boundary.
1995	*
1996	* If write=0, the page must not be written to. If the page is written to,
1997	* set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1998	* after the page is finished with, and before put_page is called.
1999	*
2000	* get_user_pages is typically used for fewer-copy IO operations, to get a
2001	* handle on the memory by some means other than accesses via the user virtual
2002	* addresses. The pages may be submitted for DMA to devices or accessed via
2003	* their kernel linear mapping (via the kmap APIs). Care should be taken to
2004	* use the correct cache flushing APIs.
2005	*
2006	* See also get_user_pages_fast, for performance critical applications.
2007	*/
2008	long get_user_pages(struct task_struct tsk, struct mm_struct mm,
2009	unsigned long start, unsigned long nr_pages, int write,
2010	int force, struct page pages, struct vm_area_struct vmas)
2011	{
2012	int flags = FOLL_TOUCH;
2013
2014	if (pages)
2015	flags \|= FOLL_GET;
2016	if (write)
2017	flags \|= FOLL_WRITE;
2018	if (force)
2019	flags \|= FOLL_FORCE;
2020
2021	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
2022	NULL);
2023	}
2024	EXPORT_SYMBOL(get_user_pages);
2025
2026	/**
2027	* get_dump_page() - pin user page in memory while writing it to core dump
2028	* @addr: user address
2029	*
2030	* Returns struct page pointer of user page pinned for dump,
2031	* to be freed afterwards by page_cache_release() or put_page().
2032	*
2033	* Returns NULL on any kind of failure - a hole must then be inserted into
2034	* the corefile, to preserve alignment with its headers; and also returns
2035	* NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
2036	* allowing a hole to be left in the corefile to save diskspace.
2037	*
2038	* Called without mmap_sem, but after all other threads have been killed.
2039	*/
2040	#ifdef CONFIG_ELF_CORE
2041	struct page *get_dump_page(unsigned long addr)
2042	{
2043	struct vm_area_struct *vma;
2044	struct page *page;
2045
2046	if (__get_user_pages(current, current->mm, addr, 1,
2047	FOLL_FORCE \| FOLL_DUMP \| FOLL_GET, &page, &vma,
2048	NULL) < 1)
2049	return NULL;
2050	flush_cache_page(vma, addr, page_to_pfn(page));
2051	return page;
2052	}
2053	#endif /* CONFIG_ELF_CORE */
2054
2055	pte_t __get_locked_pte(struct mm_struct mm, unsigned long addr,
2056	spinlock_t **ptl)
2057	{
2058	pgd_t * pgd = pgd_offset(mm, addr);
2059	pud_t * pud = pud_alloc(mm, pgd, addr);
2060	if (pud) {
2061	pmd_t * pmd = pmd_alloc(mm, pud, addr);
2062	if (pmd) {
2063	VM_BUG_ON(pmd_trans_huge(*pmd));
2064	return pte_alloc_map_lock(mm, pmd, addr, ptl);
2065	}
2066	}
2067	return NULL;
2068	}
2069
2070	/*
2071	* This is the old fallback for page remapping.
2072	*
2073	* For historical reasons, it only allows reserved pages. Only
2074	* old drivers should use this, and they needed to mark their
2075	* pages reserved for the old functions anyway.
2076	*/
2077	static int insert_page(struct vm_area_struct *vma, unsigned long addr,
2078	struct page *page, pgprot_t prot)
2079	{
2080	struct mm_struct *mm = vma->vm_mm;
2081	int retval;
2082	pte_t *pte;
2083	spinlock_t *ptl;
2084
2085	retval = -EINVAL;
2086	if (PageAnon(page))
2087	goto out;
2088	retval = -ENOMEM;
2089	flush_dcache_page(page);
2090	pte = get_locked_pte(mm, addr, &ptl);
2091	if (!pte)
2092	goto out;
2093	retval = -EBUSY;
2094	if (!pte_none(*pte))
2095	goto out_unlock;
2096
2097	/* Ok, finally just insert the thing.. */
2098	get_page(page);
2099	inc_mm_counter_fast(mm, MM_FILEPAGES);
2100	page_add_file_rmap(page);
2101	set_pte_at(mm, addr, pte, mk_pte(page, prot));
2102
2103	retval = 0;
2104	pte_unmap_unlock(pte, ptl);
2105	return retval;
2106	out_unlock:
2107	pte_unmap_unlock(pte, ptl);
2108	out:
2109	return retval;
2110	}
2111
2112	/**
2113	* vm_insert_page - insert single page into user vma
2114	* @vma: user vma to map to
2115	* @addr: target user address of this page
2116	* @page: source kernel page
2117	*
2118	* This allows drivers to insert individual pages they've allocated
2119	* into a user vma.
2120	*
2121	* The page has to be a nice clean _individual_ kernel allocation.
2122	* If you allocate a compound page, you need to have marked it as
2123	* such (__GFP_COMP), or manually just split the page up yourself
2124	* (see split_page()).
2125	*
2126	* NOTE! Traditionally this was done with "remap_pfn_range()" which
2127	* took an arbitrary page protection parameter. This doesn't allow
2128	* that. Your vma protection will have to be set up correctly, which
2129	* means that if you want a shared writable mapping, you'd better
2130	* ask for a shared writable mapping!
2131	*
2132	* The page does not need to be reserved.
2133	*
2134	* Usually this function is called from f_op->mmap() handler
2135	* under mm->mmap_sem write-lock, so it can change vma->vm_flags.
2136	* Caller must set VM_MIXEDMAP on vma if it wants to call this
2137	* function from other places, for example from page-fault handler.
2138	*/
2139	int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2140	struct page *page)
2141	{
2142	if (addr < vma->vm_start \|\| addr >= vma->vm_end)
2143	return -EFAULT;
2144	if (!page_count(page))
2145	return -EINVAL;
2146	if (!(vma->vm_flags & VM_MIXEDMAP)) {
2147	BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
2148	BUG_ON(vma->vm_flags & VM_PFNMAP);
2149	vma->vm_flags \|= VM_MIXEDMAP;
2150	}
2151	return insert_page(vma, addr, page, vma->vm_page_prot);
2152	}
2153	EXPORT_SYMBOL(vm_insert_page);
2154
2155	static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2156	unsigned long pfn, pgprot_t prot)
2157	{
2158	struct mm_struct *mm = vma->vm_mm;
2159	int retval;
2160	pte_t *pte, entry;
2161	spinlock_t *ptl;
2162
2163	retval = -ENOMEM;
2164	pte = get_locked_pte(mm, addr, &ptl);
2165	if (!pte)
2166	goto out;
2167	retval = -EBUSY;
2168	if (!pte_none(*pte))
2169	goto out_unlock;
2170
2171	/* Ok, finally just insert the thing.. */
2172	entry = pte_mkspecial(pfn_pte(pfn, prot));
2173	set_pte_at(mm, addr, pte, entry);
2174	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2175
2176	retval = 0;
2177	out_unlock:
2178	pte_unmap_unlock(pte, ptl);
2179	out:
2180	return retval;
2181	}
2182
2183	/**
2184	* vm_insert_pfn - insert single pfn into user vma
2185	* @vma: user vma to map to
2186	* @addr: target user address of this page
2187	* @pfn: source kernel pfn
2188	*
2189	* Similar to vm_insert_page, this allows drivers to insert individual pages
2190	* they've allocated into a user vma. Same comments apply.
2191	*
2192	* This function should only be called from a vm_ops->fault handler, and
2193	* in that case the handler should return NULL.
2194	*
2195	* vma cannot be a COW mapping.
2196	*
2197	* As this is called only for pages that do not currently exist, we
2198	* do not need to flush old virtual caches or the TLB.
2199	*/
2200	int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2201	unsigned long pfn)
2202	{
2203	int ret;
2204	pgprot_t pgprot = vma->vm_page_prot;
2205	/*
2206	* Technically, architectures with pte_special can avoid all these
2207	* restrictions (same for remap_pfn_range). However we would like
2208	* consistency in testing and feature parity among all, so we should
2209	* try to keep these invariants in place for everybody.
2210	*/
2211	BUG_ON(!(vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP)));
2212	BUG_ON((vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP)) ==
2213	(VM_PFNMAP\|VM_MIXEDMAP));
2214	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2215	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2216
2217	if (addr < vma->vm_start \|\| addr >= vma->vm_end)
2218	return -EFAULT;
2219	if (track_pfn_insert(vma, &pgprot, pfn))
2220	return -EINVAL;
2221
2222	ret = insert_pfn(vma, addr, pfn, pgprot);
2223
2224	return ret;
2225	}
2226	EXPORT_SYMBOL(vm_insert_pfn);
2227
2228	int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2229	unsigned long pfn)
2230	{
2231	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2232
2233	if (addr < vma->vm_start \|\| addr >= vma->vm_end)
2234	return -EFAULT;
2235
2236	/*
2237	* If we don't have pte special, then we have to use the pfn_valid()
2238	* based VM_MIXEDMAP scheme (see vm_normal_page), and thus we must
2239	* refcount the page if pfn_valid is true (hence insert_page rather
2240	* than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2241	* without pte special, it would there be refcounted as a normal page.
2242	*/
2243	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2244	struct page *page;
2245
2246	page = pfn_to_page(pfn);
2247	return insert_page(vma, addr, page, vma->vm_page_prot);
2248	}
2249	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2250	}
2251	EXPORT_SYMBOL(vm_insert_mixed);
2252
2253	/*
2254	* maps a range of physical memory into the requested pages. the old
2255	* mappings are removed. any references to nonexistent pages results
2256	* in null mappings (currently treated as "copy-on-access")
2257	*/
2258	static int remap_pte_range(struct mm_struct mm, pmd_t pmd,
2259	unsigned long addr, unsigned long end,
2260	unsigned long pfn, pgprot_t prot)
2261	{
2262	pte_t *pte;
2263	spinlock_t *ptl;
2264
2265	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2266	if (!pte)
2267	return -ENOMEM;
2268	arch_enter_lazy_mmu_mode();
2269	do {
2270	BUG_ON(!pte_none(*pte));
2271	set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2272	pfn++;
2273	} while (pte++, addr += PAGE_SIZE, addr != end);
2274	arch_leave_lazy_mmu_mode();
2275	pte_unmap_unlock(pte - 1, ptl);
2276	return 0;
2277	}
2278
2279	static inline int remap_pmd_range(struct mm_struct mm, pud_t pud,
2280	unsigned long addr, unsigned long end,
2281	unsigned long pfn, pgprot_t prot)
2282	{
2283	pmd_t *pmd;
2284	unsigned long next;
2285
2286	pfn -= addr >> PAGE_SHIFT;
2287	pmd = pmd_alloc(mm, pud, addr);
2288	if (!pmd)
2289	return -ENOMEM;
2290	VM_BUG_ON(pmd_trans_huge(*pmd));
2291	do {
2292	next = pmd_addr_end(addr, end);
2293	if (remap_pte_range(mm, pmd, addr, next,
2294	pfn + (addr >> PAGE_SHIFT), prot))
2295	return -ENOMEM;
2296	} while (pmd++, addr = next, addr != end);
2297	return 0;
2298	}
2299
2300	static inline int remap_pud_range(struct mm_struct mm, pgd_t pgd,
2301	unsigned long addr, unsigned long end,
2302	unsigned long pfn, pgprot_t prot)
2303	{
2304	pud_t *pud;
2305	unsigned long next;
2306
2307	pfn -= addr >> PAGE_SHIFT;
2308	pud = pud_alloc(mm, pgd, addr);
2309	if (!pud)
2310	return -ENOMEM;
2311	do {
2312	next = pud_addr_end(addr, end);
2313	if (remap_pmd_range(mm, pud, addr, next,
2314	pfn + (addr >> PAGE_SHIFT), prot))
2315	return -ENOMEM;
2316	} while (pud++, addr = next, addr != end);
2317	return 0;
2318	}
2319
2320	/**
2321	* remap_pfn_range - remap kernel memory to userspace
2322	* @vma: user vma to map to
2323	* @addr: target user address to start at
2324	* @pfn: physical address of kernel memory
2325	* @size: size of map area
2326	* @prot: page protection flags for this mapping
2327	*
2328	* Note: this is only safe if the mm semaphore is held when called.
2329	*/
2330	int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2331	unsigned long pfn, unsigned long size, pgprot_t prot)
2332	{
2333	pgd_t *pgd;
2334	unsigned long next;
2335	unsigned long end = addr + PAGE_ALIGN(size);
2336	struct mm_struct *mm = vma->vm_mm;
2337	int err;
2338
2339	/*
2340	* Physically remapped pages are special. Tell the
2341	* rest of the world about it:
2342	* VM_IO tells people not to look at these pages
2343	* (accesses can have side effects).
2344	* VM_PFNMAP tells the core MM that the base pages are just
2345	* raw PFN mappings, and do not have a "struct page" associated
2346	* with them.
2347	* VM_DONTEXPAND
2348	* Disable vma merging and expanding with mremap().
2349	* VM_DONTDUMP
2350	* Omit vma from core dump, even when VM_IO turned off.
2351	*
2352	* There's a horrible special case to handle copy-on-write
2353	* behaviour that some programs depend on. We mark the "original"
2354	* un-COW'ed pages by matching them up with "vma->vm_pgoff".
2355	* See vm_normal_page() for details.
2356	*/
2357	if (is_cow_mapping(vma->vm_flags)) {
2358	if (addr != vma->vm_start \|\| end != vma->vm_end)
2359	return -EINVAL;
2360	vma->vm_pgoff = pfn;
2361	}
2362
2363	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2364	if (err)
2365	return -EINVAL;
2366
2367	vma->vm_flags \|= VM_IO \| VM_PFNMAP \| VM_DONTEXPAND \| VM_DONTDUMP;
2368
2369	BUG_ON(addr >= end);
2370	pfn -= addr >> PAGE_SHIFT;
2371	pgd = pgd_offset(mm, addr);
2372	flush_cache_range(vma, addr, end);
2373	do {
2374	next = pgd_addr_end(addr, end);
2375	err = remap_pud_range(mm, pgd, addr, next,
2376	pfn + (addr >> PAGE_SHIFT), prot);
2377	if (err)
2378	break;
2379	} while (pgd++, addr = next, addr != end);
2380
2381	if (err)
2382	untrack_pfn(vma, pfn, PAGE_ALIGN(size));
2383
2384	return err;
2385	}
2386	EXPORT_SYMBOL(remap_pfn_range);
2387
2388	/**
2389	* vm_iomap_memory - remap memory to userspace
2390	* @vma: user vma to map to
2391	* @start: start of area
2392	* @len: size of area
2393	*
2394	* This is a simplified io_remap_pfn_range() for common driver use. The
2395	* driver just needs to give us the physical memory range to be mapped,
2396	* we'll figure out the rest from the vma information.
2397	*
2398	* NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2399	* whatever write-combining details or similar.
2400	*/
2401	int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2402	{
2403	unsigned long vm_len, pfn, pages;
2404
2405	/* Check that the physical memory area passed in looks valid */
2406	if (start + len < start)
2407	return -EINVAL;
2408	/*
2409	* You really shouldn't map things that aren't page-aligned,
2410	* but we've historically allowed it because IO memory might
2411	* just have smaller alignment.
2412	*/
2413	len += start & ~PAGE_MASK;
2414	pfn = start >> PAGE_SHIFT;
2415	pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2416	if (pfn + pages < pfn)
2417	return -EINVAL;
2418
2419	/* We start the mapping 'vm_pgoff' pages into the area */
2420	if (vma->vm_pgoff > pages)
2421	return -EINVAL;
2422	pfn += vma->vm_pgoff;
2423	pages -= vma->vm_pgoff;
2424
2425	/* Can we fit all of the mapping? */
2426	vm_len = vma->vm_end - vma->vm_start;
2427	if (vm_len >> PAGE_SHIFT > pages)
2428	return -EINVAL;
2429
2430	/* Ok, let it rip */
2431	return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2432	}
2433	EXPORT_SYMBOL(vm_iomap_memory);
2434
2435	static int apply_to_pte_range(struct mm_struct mm, pmd_t pmd,
2436	unsigned long addr, unsigned long end,
2437	pte_fn_t fn, void *data)
2438	{
2439	pte_t *pte;
2440	int err;
2441	pgtable_t token;
2442	spinlock_t *uninitialized_var(ptl);
2443
2444	pte = (mm == &init_mm) ?
2445	pte_alloc_kernel(pmd, addr) :
2446	pte_alloc_map_lock(mm, pmd, addr, &ptl);
2447	if (!pte)
2448	return -ENOMEM;
2449
2450	BUG_ON(pmd_huge(*pmd));
2451
2452	arch_enter_lazy_mmu_mode();
2453
2454	token = pmd_pgtable(*pmd);
2455
2456	do {
2457	err = fn(pte++, token, addr, data);
2458	if (err)
2459	break;
2460	} while (addr += PAGE_SIZE, addr != end);
2461
2462	arch_leave_lazy_mmu_mode();
2463
2464	if (mm != &init_mm)
2465	pte_unmap_unlock(pte-1, ptl);
2466	return err;
2467	}
2468
2469	static int apply_to_pmd_range(struct mm_struct mm, pud_t pud,
2470	unsigned long addr, unsigned long end,
2471	pte_fn_t fn, void *data)
2472	{
2473	pmd_t *pmd;
2474	unsigned long next;
2475	int err;
2476
2477	BUG_ON(pud_huge(*pud));
2478
2479	pmd = pmd_alloc(mm, pud, addr);
2480	if (!pmd)
2481	return -ENOMEM;
2482	do {
2483	next = pmd_addr_end(addr, end);
2484	err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2485	if (err)
2486	break;
2487	} while (pmd++, addr = next, addr != end);
2488	return err;
2489	}
2490
2491	static int apply_to_pud_range(struct mm_struct mm, pgd_t pgd,
2492	unsigned long addr, unsigned long end,
2493	pte_fn_t fn, void *data)
2494	{
2495	pud_t *pud;
2496	unsigned long next;
2497	int err;
2498
2499	pud = pud_alloc(mm, pgd, addr);
2500	if (!pud)
2501	return -ENOMEM;
2502	do {
2503	next = pud_addr_end(addr, end);
2504	err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2505	if (err)
2506	break;
2507	} while (pud++, addr = next, addr != end);
2508	return err;
2509	}
2510
2511	/*
2512	* Scan a region of virtual memory, filling in page tables as necessary
2513	* and calling a provided function on each leaf page table.
2514	*/
2515	int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2516	unsigned long size, pte_fn_t fn, void *data)
2517	{
2518	pgd_t *pgd;
2519	unsigned long next;
2520	unsigned long end = addr + size;
2521	int err;
2522
2523	BUG_ON(addr >= end);
2524	pgd = pgd_offset(mm, addr);
2525	do {
2526	next = pgd_addr_end(addr, end);
2527	err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2528	if (err)
2529	break;
2530	} while (pgd++, addr = next, addr != end);
2531
2532	return err;
2533	}
2534	EXPORT_SYMBOL_GPL(apply_to_page_range);
2535
2536	/*
2537	* handle_pte_fault chooses page fault handler according to an entry
2538	* which was read non-atomically. Before making any commitment, on
2539	* those architectures or configurations (e.g. i386 with PAE) which
2540	* might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2541	* must check under lock before unmapping the pte and proceeding
2542	* (but do_wp_page is only called after already making such a check;
2543	* and do_anonymous_page can safely check later on).
2544	*/
2545	static inline int pte_unmap_same(struct mm_struct mm, pmd_t pmd,
2546	pte_t *page_table, pte_t orig_pte)
2547	{
2548	int same = 1;
2549	#if defined(CONFIG_SMP) \|\| defined(CONFIG_PREEMPT)
2550	if (sizeof(pte_t) > sizeof(unsigned long)) {
2551	spinlock_t *ptl = pte_lockptr(mm, pmd);
2552	spin_lock(ptl);
2553	same = pte_same(*page_table, orig_pte);
2554	spin_unlock(ptl);
2555	}
2556	#endif
2557	pte_unmap(page_table);
2558	return same;
2559	}
2560
2561	static inline void cow_user_page(struct page dst, struct page src, unsigned long va, struct vm_area_struct *vma)
2562	{
2563	/*
2564	* If the source page was a PFN mapping, we don't have
2565	* a "struct page" for it. We do a best-effort copy by
2566	* just copying from the original user address. If that
2567	* fails, we just zero-fill it. Live with it.
2568	*/
2569	if (unlikely(!src)) {
2570	void *kaddr = kmap_atomic(dst);
2571	void __user uaddr = (void __user )(va & PAGE_MASK);
2572
2573	/*
2574	* This really shouldn't fail, because the page is there
2575	* in the page tables. But it might just be unreadable,
2576	* in which case we just give up and fill the result with
2577	* zeroes.
2578	*/
2579	if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2580	clear_page(kaddr);
2581	kunmap_atomic(kaddr);
2582	flush_dcache_page(dst);
2583	} else
2584	copy_user_highpage(dst, src, va, vma);
2585	}
2586
2587	/*
2588	* This routine handles present pages, when users try to write
2589	* to a shared page. It is done by copying the page to a new address
2590	* and decrementing the shared-page counter for the old page.
2591	*
2592	* Note that this routine assumes that the protection checks have been
2593	* done by the caller (the low-level page fault routine in most cases).
2594	* Thus we can safely just mark it writable once we've done any necessary
2595	* COW.
2596	*
2597	* We also mark the page dirty at this point even though the page will
2598	* change only once the write actually happens. This avoids a few races,
2599	* and potentially makes it more efficient.
2600	*
2601	* We enter with non-exclusive mmap_sem (to exclude vma changes,
2602	* but allow concurrent faults), with pte both mapped and locked.
2603	* We return with mmap_sem still held, but pte unmapped and unlocked.
2604	*/
2605	static int do_wp_page(struct mm_struct mm, struct vm_area_struct vma,
2606	unsigned long address, pte_t page_table, pmd_t pmd,
2607	spinlock_t *ptl, pte_t orig_pte)
2608	__releases(ptl)
2609	{
2610	struct page old_page, new_page = NULL;
2611	pte_t entry;
2612	int ret = 0;
2613	int page_mkwrite = 0;
2614	struct page *dirty_page = NULL;
2615	unsigned long mmun_start = 0; /* For mmu_notifiers */
2616	unsigned long mmun_end = 0; /* For mmu_notifiers */
2617
2618	old_page = vm_normal_page(vma, address, orig_pte);
2619	if (!old_page) {
2620	/*
2621	* VM_MIXEDMAP !pfn_valid() case
2622	*
2623	* We should not cow pages in a shared writeable mapping.
2624	* Just mark the pages writable as we can't do any dirty
2625	* accounting on raw pfn maps.
2626	*/
2627	if ((vma->vm_flags & (VM_WRITE\|VM_SHARED)) ==
2628	(VM_WRITE\|VM_SHARED))
2629	goto reuse;
2630	goto gotten;
2631	}
2632
2633	/*
2634	* Take out anonymous pages first, anonymous shared vmas are
2635	* not dirty accountable.
2636	*/
2637	if (PageAnon(old_page) && !PageKsm(old_page)) {
2638	if (!trylock_page(old_page)) {
2639	page_cache_get(old_page);
2640	pte_unmap_unlock(page_table, ptl);
2641	lock_page(old_page);
2642	page_table = pte_offset_map_lock(mm, pmd, address,
2643	&ptl);
2644	if (!pte_same(*page_table, orig_pte)) {
2645	unlock_page(old_page);
2646	goto unlock;
2647	}
2648	page_cache_release(old_page);
2649	}
2650	if (reuse_swap_page(old_page)) {
2651	/*
2652	* The page is all ours. Move it to our anon_vma so
2653	* the rmap code will not search our parent or siblings.
2654	* Protected against the rmap code by the page lock.
2655	*/
2656	page_move_anon_rmap(old_page, vma, address);
2657	unlock_page(old_page);
2658	goto reuse;
2659	}
2660	unlock_page(old_page);
2661	} else if (unlikely((vma->vm_flags & (VM_WRITE\|VM_SHARED)) ==
2662	(VM_WRITE\|VM_SHARED))) {
2663	/*
2664	* Only catch write-faults on shared writable pages,
2665	* read-only shared pages can get COWed by
2666	* get_user_pages(.write=1, .force=1).
2667	*/
2668	if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2669	struct vm_fault vmf;
2670	int tmp;
2671
2672	vmf.virtual_address = (void __user *)(address &
2673	PAGE_MASK);
2674	vmf.pgoff = old_page->index;
2675	vmf.flags = FAULT_FLAG_WRITE\|FAULT_FLAG_MKWRITE;
2676	vmf.page = old_page;
2677
2678	/*
2679	* Notify the address space that the page is about to
2680	* become writable so that it can prohibit this or wait
2681	* for the page to get into an appropriate state.
2682	*
2683	* We do this without the lock held, so that it can
2684	* sleep if it needs to.
2685	*/
2686	page_cache_get(old_page);
2687	pte_unmap_unlock(page_table, ptl);
2688
2689	tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2690	if (unlikely(tmp &
2691	(VM_FAULT_ERROR \| VM_FAULT_NOPAGE))) {
2692	ret = tmp;
2693	goto unwritable_page;
2694	}
2695	if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2696	lock_page(old_page);
2697	if (!old_page->mapping) {
2698	ret = 0; /* retry the fault */
2699	unlock_page(old_page);
2700	goto unwritable_page;
2701	}
2702	} else
2703	VM_BUG_ON(!PageLocked(old_page));
2704
2705	/*
2706	* Since we dropped the lock we need to revalidate
2707	* the PTE as someone else may have changed it. If
2708	* they did, we just return, as we can count on the
2709	* MMU to tell us if they didn't also make it writable.
2710	*/
2711	page_table = pte_offset_map_lock(mm, pmd, address,
2712	&ptl);
2713	if (!pte_same(*page_table, orig_pte)) {
2714	unlock_page(old_page);
2715	goto unlock;
2716	}
2717
2718	page_mkwrite = 1;
2719	}
2720	dirty_page = old_page;
2721	get_page(dirty_page);
2722
2723	reuse:
2724	flush_cache_page(vma, address, pte_pfn(orig_pte));
2725	entry = pte_mkyoung(orig_pte);
2726	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2727	if (ptep_set_access_flags(vma, address, page_table, entry,1))
2728	update_mmu_cache(vma, address, page_table);
2729	pte_unmap_unlock(page_table, ptl);
2730	ret \|= VM_FAULT_WRITE;
2731
2732	if (!dirty_page)
2733	return ret;
2734
2735	/*
2736	* Yes, Virginia, this is actually required to prevent a race
2737	* with clear_page_dirty_for_io() from clearing the page dirty
2738	* bit after it clear all dirty ptes, but before a racing
2739	* do_wp_page installs a dirty pte.
2740	*
2741	* __do_fault is protected similarly.
2742	*/
2743	if (!page_mkwrite) {
2744	wait_on_page_locked(dirty_page);
2745	set_page_dirty_balance(dirty_page, page_mkwrite);
2746	/* file_update_time outside page_lock */
2747	if (vma->vm_file)
2748	file_update_time(vma->vm_file);
2749	}
2750	put_page(dirty_page);
2751	if (page_mkwrite) {
2752	struct address_space *mapping = dirty_page->mapping;
2753
2754	set_page_dirty(dirty_page);
2755	unlock_page(dirty_page);
2756	page_cache_release(dirty_page);
2757	if (mapping) {
2758	/*
2759	* Some device drivers do not set page.mapping
2760	* but still dirty their pages
2761	*/
2762	balance_dirty_pages_ratelimited(mapping);
2763	}
2764	}
2765
2766	return ret;
2767	}
2768
2769	/*
2770	* Ok, we need to copy. Oh, well..
2771	*/
2772	page_cache_get(old_page);
2773	gotten:
2774	pte_unmap_unlock(page_table, ptl);
2775
2776	if (unlikely(anon_vma_prepare(vma)))
2777	goto oom;
2778
2779	if (is_zero_pfn(pte_pfn(orig_pte))) {
2780	new_page = alloc_zeroed_user_highpage_movable(vma, address);
2781	if (!new_page)
2782	goto oom;
2783	} else {
2784	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2785	if (!new_page)
2786	goto oom;
2787	cow_user_page(new_page, old_page, address, vma);
2788	}
2789	__SetPageUptodate(new_page);
2790
2791	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2792	goto oom_free_new;
2793
2794	mmun_start = address & PAGE_MASK;
2795	mmun_end = mmun_start + PAGE_SIZE;
2796	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2797
2798	/*
2799	* Re-check the pte - we dropped the lock
2800	*/
2801	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2802	if (likely(pte_same(*page_table, orig_pte))) {
2803	if (old_page) {
2804	if (!PageAnon(old_page)) {
2805	dec_mm_counter_fast(mm, MM_FILEPAGES);
2806	inc_mm_counter_fast(mm, MM_ANONPAGES);
2807	}
2808	} else
2809	inc_mm_counter_fast(mm, MM_ANONPAGES);
2810	flush_cache_page(vma, address, pte_pfn(orig_pte));
2811	entry = mk_pte(new_page, vma->vm_page_prot);
2812	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2813	/*
2814	* Clear the pte entry and flush it first, before updating the
2815	* pte with the new entry. This will avoid a race condition
2816	* seen in the presence of one thread doing SMC and another
2817	* thread doing COW.
2818	*/
2819	ptep_clear_flush(vma, address, page_table);
2820	page_add_new_anon_rmap(new_page, vma, address);
2821	/*
2822	* We call the notify macro here because, when using secondary
2823	* mmu page tables (such as kvm shadow page tables), we want the
2824	* new page to be mapped directly into the secondary page table.
2825	*/
2826	set_pte_at_notify(mm, address, page_table, entry);
2827	update_mmu_cache(vma, address, page_table);
2828	if (old_page) {
2829	/*
2830	* Only after switching the pte to the new page may
2831	* we remove the mapcount here. Otherwise another
2832	* process may come and find the rmap count decremented
2833	* before the pte is switched to the new page, and
2834	* "reuse" the old page writing into it while our pte
2835	* here still points into it and can be read by other
2836	* threads.
2837	*
2838	* The critical issue is to order this
2839	* page_remove_rmap with the ptp_clear_flush above.
2840	* Those stores are ordered by (if nothing else,)
2841	* the barrier present in the atomic_add_negative
2842	* in page_remove_rmap.
2843	*
2844	* Then the TLB flush in ptep_clear_flush ensures that
2845	* no process can access the old page before the
2846	* decremented mapcount is visible. And the old page
2847	* cannot be reused until after the decremented
2848	* mapcount is visible. So transitively, TLBs to
2849	* old page will be flushed before it can be reused.
2850	*/
2851	page_remove_rmap(old_page);
2852	}
2853
2854	/* Free the old page.. */
2855	new_page = old_page;
2856	ret \|= VM_FAULT_WRITE;
2857	} else
2858	mem_cgroup_uncharge_page(new_page);
2859
2860	if (new_page)
2861	page_cache_release(new_page);
2862	unlock:
2863	pte_unmap_unlock(page_table, ptl);
2864	if (mmun_end > mmun_start)
2865	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2866	if (old_page) {
2867	/*
2868	* Don't let another task, with possibly unlocked vma,
2869	* keep the mlocked page.
2870	*/
2871	if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2872	lock_page(old_page); /* LRU manipulation */
2873	munlock_vma_page(old_page);
2874	unlock_page(old_page);
2875	}
2876	page_cache_release(old_page);
2877	}
2878	return ret;
2879	oom_free_new:
2880	page_cache_release(new_page);
2881	oom:
2882	if (old_page)
2883	page_cache_release(old_page);
2884	return VM_FAULT_OOM;
2885
2886	unwritable_page:
2887	page_cache_release(old_page);
2888	return ret;
2889	}
2890
2891	static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2892	unsigned long start_addr, unsigned long end_addr,
2893	struct zap_details *details)
2894	{
2895	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2896	}
2897
2898	static inline void unmap_mapping_range_tree(struct rb_root *root,
2899	struct zap_details *details)
2900	{
2901	struct vm_area_struct *vma;
2902	pgoff_t vba, vea, zba, zea;
2903
2904	vma_interval_tree_foreach(vma, root,
2905	details->first_index, details->last_index) {
2906
2907	vba = vma->vm_pgoff;
2908	vea = vba + vma_pages(vma) - 1;
2909	/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2910	zba = details->first_index;
2911	if (zba < vba)
2912	zba = vba;
2913	zea = details->last_index;
2914	if (zea > vea)
2915	zea = vea;
2916
2917	unmap_mapping_range_vma(vma,
2918	((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2919	((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2920	details);
2921	}
2922	}
2923
2924	static inline void unmap_mapping_range_list(struct list_head *head,
2925	struct zap_details *details)
2926	{
2927	struct vm_area_struct *vma;
2928
2929	/*
2930	* In nonlinear VMAs there is no correspondence between virtual address
2931	* offset and file offset. So we must perform an exhaustive search
2932	* across all the pages in each nonlinear VMA, not just the pages
2933	* whose virtual address lies outside the file truncation point.
2934	*/
2935	list_for_each_entry(vma, head, shared.nonlinear) {
2936	details->nonlinear_vma = vma;
2937	unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2938	}
2939	}
2940
2941	/**
2942	* unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2943	* @mapping: the address space containing mmaps to be unmapped.
2944	* @holebegin: byte in first page to unmap, relative to the start of
2945	* the underlying file. This will be rounded down to a PAGE_SIZE
2946	* boundary. Note that this is different from truncate_pagecache(), which
2947	* must keep the partial page. In contrast, we must get rid of
2948	* partial pages.
2949	* @holelen: size of prospective hole in bytes. This will be rounded
2950	* up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2951	* end of the file.
2952	* @even_cows: 1 when truncating a file, unmap even private COWed pages;
2953	* but 0 when invalidating pagecache, don't throw away private data.
2954	*/
2955	void unmap_mapping_range(struct address_space *mapping,
2956	loff_t const holebegin, loff_t const holelen, int even_cows)
2957	{
2958	struct zap_details details;
2959	pgoff_t hba = holebegin >> PAGE_SHIFT;
2960	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2961
2962	/* Check for overflow. */
2963	if (sizeof(holelen) > sizeof(hlen)) {
2964	long long holeend =
2965	(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2966	if (holeend & ~(long long)ULONG_MAX)
2967	hlen = ULONG_MAX - hba + 1;
2968	}
2969
2970	details.check_mapping = even_cows? NULL: mapping;
2971	details.nonlinear_vma = NULL;
2972	details.first_index = hba;
2973	details.last_index = hba + hlen - 1;
2974	if (details.last_index < details.first_index)
2975	details.last_index = ULONG_MAX;
2976
2977
2978	mutex_lock(&mapping->i_mmap_mutex);
2979	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2980	unmap_mapping_range_tree(&mapping->i_mmap, &details);
2981	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2982	unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2983	mutex_unlock(&mapping->i_mmap_mutex);
2984	}
2985	EXPORT_SYMBOL(unmap_mapping_range);
2986
2987	/*
2988	* We enter with non-exclusive mmap_sem (to exclude vma changes,
2989	* but allow concurrent faults), and pte mapped but not yet locked.
2990	* We return with mmap_sem still held, but pte unmapped and unlocked.
2991	*/
2992	static int do_swap_page(struct mm_struct mm, struct vm_area_struct vma,
2993	unsigned long address, pte_t page_table, pmd_t pmd,
2994	unsigned int flags, pte_t orig_pte)
2995	{
2996	spinlock_t *ptl;
2997	struct page page, swapcache;
2998	swp_entry_t entry;
2999	pte_t pte;
3000	int locked;
3001	struct mem_cgroup *ptr;
3002	int exclusive = 0;
3003	int ret = 0;
3004
3005	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3006	goto out;
3007
3008	entry = pte_to_swp_entry(orig_pte);
3009	if (unlikely(non_swap_entry(entry))) {
3010	if (is_migration_entry(entry)) {
3011	migration_entry_wait(mm, pmd, address);
3012	} else if (is_hwpoison_entry(entry)) {
3013	ret = VM_FAULT_HWPOISON;
3014	} else {
3015	print_bad_pte(vma, address, orig_pte, NULL);
3016	ret = VM_FAULT_SIGBUS;
3017	}
3018	goto out;
3019	}
3020	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
3021	page = lookup_swap_cache(entry);
3022	if (!page) {
3023	page = swapin_readahead(entry,
3024	GFP_HIGHUSER_MOVABLE, vma, address);
3025	if (!page) {
3026	/*
3027	* Back out if somebody else faulted in this pte
3028	* while we released the pte lock.
3029	*/
3030	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3031	if (likely(pte_same(*page_table, orig_pte)))
3032	ret = VM_FAULT_OOM;
3033	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3034	goto unlock;
3035	}
3036
3037	/* Had to read the page from swap area: Major fault */
3038	ret = VM_FAULT_MAJOR;
3039	count_vm_event(PGMAJFAULT);
3040	mem_cgroup_count_vm_event(mm, PGMAJFAULT);
3041	} else if (PageHWPoison(page)) {
3042	/*
3043	* hwpoisoned dirty swapcache pages are kept for killing
3044	* owner processes (which may be unknown at hwpoison time)
3045	*/
3046	ret = VM_FAULT_HWPOISON;
3047	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3048	swapcache = page;
3049	goto out_release;
3050	}
3051
3052	swapcache = page;
3053	locked = lock_page_or_retry(page, mm, flags);
3054
3055	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3056	if (!locked) {
3057	ret \|= VM_FAULT_RETRY;
3058	goto out_release;
3059	}
3060
3061	/*
3062	* Make sure try_to_free_swap or reuse_swap_page or swapoff did not
3063	* release the swapcache from under us. The page pin, and pte_same
3064	* test below, are not enough to exclude that. Even if it is still
3065	* swapcache, we need to check that the page's swap has not changed.
3066	*/
3067	if (unlikely(!PageSwapCache(page) \|\| page_private(page) != entry.val))
3068	goto out_page;
3069
3070	page = ksm_might_need_to_copy(page, vma, address);
3071	if (unlikely(!page)) {
3072	ret = VM_FAULT_OOM;
3073	page = swapcache;
3074	goto out_page;
3075	}
3076
3077	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
3078	ret = VM_FAULT_OOM;
3079	goto out_page;
3080	}
3081
3082	/*
3083	* Back out if somebody else already faulted in this pte.
3084	*/
3085	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3086	if (unlikely(!pte_same(*page_table, orig_pte)))
3087	goto out_nomap;
3088
3089	if (unlikely(!PageUptodate(page))) {
3090	ret = VM_FAULT_SIGBUS;
3091	goto out_nomap;
3092	}
3093
3094	/*
3095	* The page isn't present yet, go ahead with the fault.
3096	*
3097	* Be careful about the sequence of operations here.
3098	* To get its accounting right, reuse_swap_page() must be called
3099	* while the page is counted on swap but not yet in mapcount i.e.
3100	* before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3101	* must be called after the swap_free(), or it will never succeed.
3102	* Because delete_from_swap_page() may be called by reuse_swap_page(),
3103	* mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
3104	* in page->private. In this case, a record in swap_cgroup is silently
3105	* discarded at swap_free().
3106	*/
3107
3108	inc_mm_counter_fast(mm, MM_ANONPAGES);
3109	dec_mm_counter_fast(mm, MM_SWAPENTS);
3110	pte = mk_pte(page, vma->vm_page_prot);
3111	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
3112	pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3113	flags &= ~FAULT_FLAG_WRITE;
3114	ret \|= VM_FAULT_WRITE;
3115	exclusive = 1;
3116	}
3117	flush_icache_page(vma, page);
3118	if (pte_swp_soft_dirty(orig_pte))
3119	pte = pte_mksoft_dirty(pte);
3120	set_pte_at(mm, address, page_table, pte);
3121	if (page == swapcache)
3122	do_page_add_anon_rmap(page, vma, address, exclusive);
3123	else /* ksm created a completely new copy */
3124	page_add_new_anon_rmap(page, vma, address);
3125	/* It's better to call commit-charge after rmap is established */
3126	mem_cgroup_commit_charge_swapin(page, ptr);
3127
3128	swap_free(entry);
3129	if (vm_swap_full() \|\| (vma->vm_flags & VM_LOCKED) \|\| PageMlocked(page))
3130	try_to_free_swap(page);
3131	unlock_page(page);
3132	if (page != swapcache) {
3133	/*
3134	* Hold the lock to avoid the swap entry to be reused
3135	* until we take the PT lock for the pte_same() check
3136	* (to avoid false positives from pte_same). For
3137	* further safety release the lock after the swap_free
3138	* so that the swap count won't change under a
3139	* parallel locked swapcache.
3140	*/
3141	unlock_page(swapcache);
3142	page_cache_release(swapcache);
3143	}
3144
3145	if (flags & FAULT_FLAG_WRITE) {
3146	ret \|= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3147	if (ret & VM_FAULT_ERROR)
3148	ret &= VM_FAULT_ERROR;
3149	goto out;
3150	}
3151
3152	/* No need to invalidate - it was non-present before */
3153	update_mmu_cache(vma, address, page_table);
3154	unlock:
3155	pte_unmap_unlock(page_table, ptl);
3156	out:
3157	return ret;
3158	out_nomap:
3159	mem_cgroup_cancel_charge_swapin(ptr);
3160	pte_unmap_unlock(page_table, ptl);
3161	out_page:
3162	unlock_page(page);
3163	out_release:
3164	page_cache_release(page);
3165	if (page != swapcache) {
3166	unlock_page(swapcache);
3167	page_cache_release(swapcache);
3168	}
3169	return ret;
3170	}
3171
3172	/*
3173	* This is like a special single-page "expand_{down\|up}wards()",
3174	* except we must first make sure that 'address{-\|+}PAGE_SIZE'
3175	* doesn't hit another vma.
3176	*/
3177	static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3178	{
3179	address &= PAGE_MASK;
3180	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3181	struct vm_area_struct *prev = vma->vm_prev;
3182
3183	/*
3184	* Is there a mapping abutting this one below?
3185	*
3186	* That's only ok if it's the same stack mapping
3187	* that has gotten split..
3188	*/
3189	if (prev && prev->vm_end == address)
3190	return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3191
3192	expand_downwards(vma, address - PAGE_SIZE);
3193	}
3194	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3195	struct vm_area_struct *next = vma->vm_next;
3196
3197	/* As VM_GROWSDOWN but s/below/above/ */
3198	if (next && next->vm_start == address + PAGE_SIZE)
3199	return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3200
3201	expand_upwards(vma, address + PAGE_SIZE);
3202	}
3203	return 0;
3204	}
3205
3206	/*
3207	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3208	* but allow concurrent faults), and pte mapped but not yet locked.
3209	* We return with mmap_sem still held, but pte unmapped and unlocked.
3210	*/
3211	static int do_anonymous_page(struct mm_struct mm, struct vm_area_struct vma,
3212	unsigned long address, pte_t page_table, pmd_t pmd,
3213	unsigned int flags)
3214	{
3215	struct page *page;
3216	spinlock_t *ptl;
3217	pte_t entry;
3218
3219	pte_unmap(page_table);
3220
3221	/* Check if we need to add a guard page to the stack */
3222	if (check_stack_guard_page(vma, address) < 0)
3223	return VM_FAULT_SIGBUS;
3224
3225	/* Use the zero-page for reads */
3226	if (!(flags & FAULT_FLAG_WRITE)) {
3227	entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3228	vma->vm_page_prot));
3229	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3230	if (!pte_none(*page_table))
3231	goto unlock;
3232	goto setpte;
3233	}
3234
3235	/* Allocate our own private page. */
3236	if (unlikely(anon_vma_prepare(vma)))
3237	goto oom;
3238	page = alloc_zeroed_user_highpage_movable(vma, address);
3239	if (!page)
3240	goto oom;
3241	/*
3242	* The memory barrier inside __SetPageUptodate makes sure that
3243	* preceeding stores to the page contents become visible before
3244	* the set_pte_at() write.
3245	*/
3246	__SetPageUptodate(page);
3247
3248	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3249	goto oom_free_page;
3250
3251	entry = mk_pte(page, vma->vm_page_prot);
3252	if (vma->vm_flags & VM_WRITE)
3253	entry = pte_mkwrite(pte_mkdirty(entry));
3254
3255	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3256	if (!pte_none(*page_table))
3257	goto release;
3258
3259	inc_mm_counter_fast(mm, MM_ANONPAGES);
3260	page_add_new_anon_rmap(page, vma, address);
3261	setpte:
3262	set_pte_at(mm, address, page_table, entry);
3263
3264	/* No need to invalidate - it was non-present before */
3265	update_mmu_cache(vma, address, page_table);
3266	unlock:
3267	pte_unmap_unlock(page_table, ptl);
3268	return 0;
3269	release:
3270	mem_cgroup_uncharge_page(page);
3271	page_cache_release(page);
3272	goto unlock;
3273	oom_free_page:
3274	page_cache_release(page);
3275	oom:
3276	return VM_FAULT_OOM;
3277	}
3278
3279	/*
3280	* __do_fault() tries to create a new page mapping. It aggressively
3281	* tries to share with existing pages, but makes a separate copy if
3282	* the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3283	* the next page fault.
3284	*
3285	* As this is called only for pages that do not currently exist, we
3286	* do not need to flush old virtual caches or the TLB.
3287	*
3288	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3289	* but allow concurrent faults), and pte neither mapped nor locked.
3290	* We return with mmap_sem still held, but pte unmapped and unlocked.
3291	*/
3292	static int __do_fault(struct mm_struct mm, struct vm_area_struct vma,
3293	unsigned long address, pmd_t *pmd,
3294	pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3295	{
3296	pte_t *page_table;
3297	spinlock_t *ptl;
3298	struct page *page;
3299	struct page *cow_page;
3300	pte_t entry;
3301	int anon = 0;
3302	struct page *dirty_page = NULL;
3303	struct vm_fault vmf;
3304	int ret;
3305	int page_mkwrite = 0;
3306
3307	/*
3308	* If we do COW later, allocate page befor taking lock_page()
3309	* on the file cache page. This will reduce lock holding time.
3310	*/
3311	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3312
3313	if (unlikely(anon_vma_prepare(vma)))
3314	return VM_FAULT_OOM;
3315
3316	cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3317	if (!cow_page)
3318	return VM_FAULT_OOM;
3319
3320	if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
3321	page_cache_release(cow_page);
3322	return VM_FAULT_OOM;
3323	}
3324	} else
3325	cow_page = NULL;
3326
3327	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3328	vmf.pgoff = pgoff;
3329	vmf.flags = flags;
3330	vmf.page = NULL;
3331
3332	ret = vma->vm_ops->fault(vma, &vmf);
3333	if (unlikely(ret & (VM_FAULT_ERROR \| VM_FAULT_NOPAGE \|
3334	VM_FAULT_RETRY)))
3335	goto uncharge_out;
3336
3337	if (unlikely(PageHWPoison(vmf.page))) {
3338	if (ret & VM_FAULT_LOCKED)
3339	unlock_page(vmf.page);
3340	ret = VM_FAULT_HWPOISON;
3341	goto uncharge_out;
3342	}
3343
3344	/*
3345	* For consistency in subsequent calls, make the faulted page always
3346	* locked.
3347	*/
3348	if (unlikely(!(ret & VM_FAULT_LOCKED)))
3349	lock_page(vmf.page);
3350	else
3351	VM_BUG_ON(!PageLocked(vmf.page));
3352
3353	/*
3354	* Should we do an early C-O-W break?
3355	*/
3356	page = vmf.page;
3357	if (flags & FAULT_FLAG_WRITE) {
3358	if (!(vma->vm_flags & VM_SHARED)) {
3359	page = cow_page;
3360	anon = 1;
3361	copy_user_highpage(page, vmf.page, address, vma);
3362	__SetPageUptodate(page);
3363	} else {
3364	/*
3365	* If the page will be shareable, see if the backing
3366	* address space wants to know that the page is about
3367	* to become writable
3368	*/
3369	if (vma->vm_ops->page_mkwrite) {
3370	int tmp;
3371
3372	unlock_page(page);
3373	vmf.flags = FAULT_FLAG_WRITE\|FAULT_FLAG_MKWRITE;
3374	tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3375	if (unlikely(tmp &
3376	(VM_FAULT_ERROR \| VM_FAULT_NOPAGE))) {
3377	ret = tmp;
3378	goto unwritable_page;
3379	}
3380	if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3381	lock_page(page);
3382	if (!page->mapping) {
3383	ret = 0; /* retry the fault */
3384	unlock_page(page);
3385	goto unwritable_page;
3386	}
3387	} else
3388	VM_BUG_ON(!PageLocked(page));
3389	page_mkwrite = 1;
3390	}
3391	}
3392
3393	}
3394
3395	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3396
3397	/*
3398	* This silly early PAGE_DIRTY setting removes a race
3399	* due to the bad i386 page protection. But it's valid
3400	* for other architectures too.
3401	*
3402	* Note that if FAULT_FLAG_WRITE is set, we either now have
3403	* an exclusive copy of the page, or this is a shared mapping,
3404	* so we can make it writable and dirty to avoid having to
3405	* handle that later.
3406	*/
3407	/* Only go through if we didn't race with anybody else... */
3408	if (likely(pte_same(*page_table, orig_pte))) {
3409	flush_icache_page(vma, page);
3410	entry = mk_pte(page, vma->vm_page_prot);
3411	if (flags & FAULT_FLAG_WRITE)
3412	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3413	else if (pte_file(orig_pte) && pte_file_soft_dirty(orig_pte))
3414	pte_mksoft_dirty(entry);
3415	if (anon) {
3416	inc_mm_counter_fast(mm, MM_ANONPAGES);
3417	page_add_new_anon_rmap(page, vma, address);
3418	} else {
3419	inc_mm_counter_fast(mm, MM_FILEPAGES);
3420	page_add_file_rmap(page);
3421	if (flags & FAULT_FLAG_WRITE) {
3422	dirty_page = page;
3423	get_page(dirty_page);
3424	}
3425	}
3426	set_pte_at(mm, address, page_table, entry);
3427
3428	/* no need to invalidate: a not-present page won't be cached */
3429	update_mmu_cache(vma, address, page_table);
3430	} else {
3431	if (cow_page)
3432	mem_cgroup_uncharge_page(cow_page);
3433	if (anon)
3434	page_cache_release(page);
3435	else
3436	anon = 1; /* no anon but release faulted_page */
3437	}
3438
3439	pte_unmap_unlock(page_table, ptl);
3440
3441	if (dirty_page) {
3442	struct address_space *mapping = page->mapping;
3443	int dirtied = 0;
3444
3445	if (set_page_dirty(dirty_page))
3446	dirtied = 1;
3447	unlock_page(dirty_page);
3448	put_page(dirty_page);
3449	if ((dirtied \|\| page_mkwrite) && mapping) {
3450	/*
3451	* Some device drivers do not set page.mapping but still
3452	* dirty their pages
3453	*/
3454	balance_dirty_pages_ratelimited(mapping);
3455	}
3456
3457	/* file_update_time outside page_lock */
3458	if (vma->vm_file && !page_mkwrite)
3459	file_update_time(vma->vm_file);
3460	} else {
3461	unlock_page(vmf.page);
3462	if (anon)
3463	page_cache_release(vmf.page);
3464	}
3465
3466	return ret;
3467
3468	unwritable_page:
3469	page_cache_release(page);
3470	return ret;
3471	uncharge_out:
3472	/* fs's fault handler get error */
3473	if (cow_page) {
3474	mem_cgroup_uncharge_page(cow_page);
3475	page_cache_release(cow_page);
3476	}
3477	return ret;
3478	}
3479
3480	static int do_linear_fault(struct mm_struct mm, struct vm_area_struct vma,
3481	unsigned long address, pte_t page_table, pmd_t pmd,
3482	unsigned int flags, pte_t orig_pte)
3483	{
3484	pgoff_t pgoff = (((address & PAGE_MASK)
3485	- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3486
3487	pte_unmap(page_table);
3488	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3489	}
3490
3491	/*
3492	* Fault of a previously existing named mapping. Repopulate the pte
3493	* from the encoded file_pte if possible. This enables swappable
3494	* nonlinear vmas.
3495	*
3496	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3497	* but allow concurrent faults), and pte mapped but not yet locked.
3498	* We return with mmap_sem still held, but pte unmapped and unlocked.
3499	*/
3500	static int do_nonlinear_fault(struct mm_struct mm, struct vm_area_struct vma,
3501	unsigned long address, pte_t page_table, pmd_t pmd,
3502	unsigned int flags, pte_t orig_pte)
3503	{
3504	pgoff_t pgoff;
3505
3506	flags \|= FAULT_FLAG_NONLINEAR;
3507
3508	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3509	return 0;
3510
3511	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3512	/*
3513	* Page table corrupted: show pte and kill process.
3514	*/
3515	print_bad_pte(vma, address, orig_pte, NULL);
3516	return VM_FAULT_SIGBUS;
3517	}
3518
3519	pgoff = pte_to_pgoff(orig_pte);
3520	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3521	}
3522
3523	int numa_migrate_prep(struct page page, struct vm_area_struct vma,
3524	unsigned long addr, int page_nid)
3525	{
3526	get_page(page);
3527
3528	count_vm_numa_event(NUMA_HINT_FAULTS);
3529	if (page_nid == numa_node_id())
3530	count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3531
3532	return mpol_misplaced(page, vma, addr);
3533	}
3534
3535	int do_numa_page(struct mm_struct mm, struct vm_area_struct vma,
3536	unsigned long addr, pte_t pte, pte_t ptep, pmd_t pmd)
3537	{
3538	struct page *page = NULL;
3539	spinlock_t *ptl;
3540	int page_nid = -1;
3541	int target_nid;
3542	bool migrated = false;
3543
3544	/*
3545	* The "pte" at this point cannot be used safely without
3546	* validation through pte_unmap_same(). It's of NUMA type but
3547	* the pfn may be screwed if the read is non atomic.
3548	*
3549	* ptep_modify_prot_start is not called as this is clearing
3550	* the _PAGE_NUMA bit and it is not really expected that there
3551	* would be concurrent hardware modifications to the PTE.
3552	*/
3553	ptl = pte_lockptr(mm, pmd);
3554	spin_lock(ptl);
3555	if (unlikely(!pte_same(*ptep, pte))) {
3556	pte_unmap_unlock(ptep, ptl);
3557	goto out;
3558	}
3559
3560	pte = pte_mknonnuma(pte);
3561	set_pte_at(mm, addr, ptep, pte);
3562	update_mmu_cache(vma, addr, ptep);
3563
3564	page = vm_normal_page(vma, addr, pte);
3565	if (!page) {
3566	pte_unmap_unlock(ptep, ptl);
3567	return 0;
3568	}
3569
3570	page_nid = page_to_nid(page);
3571	target_nid = numa_migrate_prep(page, vma, addr, page_nid);
3572	pte_unmap_unlock(ptep, ptl);
3573	if (target_nid == -1) {
3574	put_page(page);
3575	goto out;
3576	}
3577
3578	/* Migrate to the requested node */
3579	migrated = migrate_misplaced_page(page, target_nid);
3580	if (migrated)
3581	page_nid = target_nid;
3582
3583	out:
3584	if (page_nid != -1)
3585	task_numa_fault(page_nid, 1, migrated);
3586	return 0;
3587	}
3588
3589	/* NUMA hinting page fault entry point for regular pmds */
3590	#ifdef CONFIG_NUMA_BALANCING
3591	static int do_pmd_numa_page(struct mm_struct mm, struct vm_area_struct vma,
3592	unsigned long addr, pmd_t *pmdp)
3593	{
3594	pmd_t pmd;
3595	pte_t pte, orig_pte;
3596	unsigned long _addr = addr & PMD_MASK;
3597	unsigned long offset;
3598	spinlock_t *ptl;
3599	bool numa = false;
3600
3601	spin_lock(&mm->page_table_lock);
3602	pmd = *pmdp;
3603	if (pmd_numa(pmd)) {
3604	set_pmd_at(mm, _addr, pmdp, pmd_mknonnuma(pmd));
3605	numa = true;
3606	}
3607	spin_unlock(&mm->page_table_lock);
3608
3609	if (!numa)
3610	return 0;
3611
3612	/* we're in a page fault so some vma must be in the range */
3613	BUG_ON(!vma);
3614	BUG_ON(vma->vm_start >= _addr + PMD_SIZE);
3615	offset = max(_addr, vma->vm_start) & ~PMD_MASK;
3616	VM_BUG_ON(offset >= PMD_SIZE);
3617	orig_pte = pte = pte_offset_map_lock(mm, pmdp, _addr, &ptl);
3618	pte += offset >> PAGE_SHIFT;
3619	for (addr = _addr + offset; addr < _addr + PMD_SIZE; pte++, addr += PAGE_SIZE) {
3620	pte_t pteval = *pte;
3621	struct page *page;
3622	int page_nid = -1;
3623	int target_nid;
3624	bool migrated = false;
3625
3626	if (!pte_present(pteval))
3627	continue;
3628	if (!pte_numa(pteval))
3629	continue;
3630	if (addr >= vma->vm_end) {
3631	vma = find_vma(mm, addr);
3632	/* there's a pte present so there must be a vma */
3633	BUG_ON(!vma);
3634	BUG_ON(addr < vma->vm_start);
3635	}
3636	if (pte_numa(pteval)) {
3637	pteval = pte_mknonnuma(pteval);
3638	set_pte_at(mm, addr, pte, pteval);
3639	}
3640	page = vm_normal_page(vma, addr, pteval);
3641	if (unlikely(!page))
3642	continue;
3643	/* only check non-shared pages */
3644	if (unlikely(page_mapcount(page) != 1))
3645	continue;
3646
3647	page_nid = page_to_nid(page);
3648	target_nid = numa_migrate_prep(page, vma, addr, page_nid);
3649	pte_unmap_unlock(pte, ptl);
3650	if (target_nid != -1) {
3651	migrated = migrate_misplaced_page(page, target_nid);
3652	if (migrated)
3653	page_nid = target_nid;
3654	} else {
3655	put_page(page);
3656	}
3657
3658	if (page_nid != -1)
3659	task_numa_fault(page_nid, 1, migrated);
3660
3661	pte = pte_offset_map_lock(mm, pmdp, addr, &ptl);
3662	}
3663	pte_unmap_unlock(orig_pte, ptl);
3664
3665	return 0;
3666	}
3667	#else
3668	static int do_pmd_numa_page(struct mm_struct mm, struct vm_area_struct vma,
3669	unsigned long addr, pmd_t *pmdp)
3670	{
3671	BUG();
3672	return 0;
3673	}
3674	#endif /* CONFIG_NUMA_BALANCING */
3675
3676	/*
3677	* These routines also need to handle stuff like marking pages dirty
3678	* and/or accessed for architectures that don't do it in hardware (most
3679	* RISC architectures). The early dirtying is also good on the i386.
3680	*
3681	* There is also a hook called "update_mmu_cache()" that architectures
3682	* with external mmu caches can use to update those (ie the Sparc or
3683	* PowerPC hashed page tables that act as extended TLBs).
3684	*
3685	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3686	* but allow concurrent faults), and pte mapped but not yet locked.
3687	* We return with mmap_sem still held, but pte unmapped and unlocked.
3688	*/
3689	static int handle_pte_fault(struct mm_struct *mm,
3690	struct vm_area_struct *vma, unsigned long address,
3691	pte_t pte, pmd_t pmd, unsigned int flags)
3692	{
3693	pte_t entry;
3694	spinlock_t *ptl;
3695
3696	entry = *pte;
3697	if (!pte_present(entry)) {
3698	if (pte_none(entry)) {
3699	if (vma->vm_ops) {
3700	if (likely(vma->vm_ops->fault))
3701	return do_linear_fault(mm, vma, address,
3702	pte, pmd, flags, entry);
3703	}
3704	return do_anonymous_page(mm, vma, address,
3705	pte, pmd, flags);
3706	}
3707	if (pte_file(entry))
3708	return do_nonlinear_fault(mm, vma, address,
3709	pte, pmd, flags, entry);
3710	return do_swap_page(mm, vma, address,
3711	pte, pmd, flags, entry);
3712	}
3713
3714	if (pte_numa(entry))
3715	return do_numa_page(mm, vma, address, entry, pte, pmd);
3716
3717	ptl = pte_lockptr(mm, pmd);
3718	spin_lock(ptl);
3719	if (unlikely(!pte_same(*pte, entry)))
3720	goto unlock;
3721	if (flags & FAULT_FLAG_WRITE) {
3722	if (!pte_write(entry))
3723	return do_wp_page(mm, vma, address,
3724	pte, pmd, ptl, entry);
3725	entry = pte_mkdirty(entry);
3726	}
3727	entry = pte_mkyoung(entry);
3728	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3729	update_mmu_cache(vma, address, pte);
3730	} else {
3731	/*
3732	* This is needed only for protection faults but the arch code
3733	* is not yet telling us if this is a protection fault or not.
3734	* This still avoids useless tlb flushes for .text page faults
3735	* with threads.
3736	*/
3737	if (flags & FAULT_FLAG_WRITE)
3738	flush_tlb_fix_spurious_fault(vma, address);
3739	}
3740	unlock:
3741	pte_unmap_unlock(pte, ptl);
3742	return 0;
3743	}
3744
3745	/*
3746	* By the time we get here, we already hold the mm semaphore
3747	*/
3748	static int __handle_mm_fault(struct mm_struct mm, struct vm_area_struct vma,
3749	unsigned long address, unsigned int flags)
3750	{
3751	pgd_t *pgd;
3752	pud_t *pud;
3753	pmd_t *pmd;
3754	pte_t *pte;
3755
3756	if (unlikely(is_vm_hugetlb_page(vma)))
3757	return hugetlb_fault(mm, vma, address, flags);
3758
3759	retry:
3760	pgd = pgd_offset(mm, address);
3761	pud = pud_alloc(mm, pgd, address);
3762	if (!pud)
3763	return VM_FAULT_OOM;
3764	pmd = pmd_alloc(mm, pud, address);
3765	if (!pmd)
3766	return VM_FAULT_OOM;
3767	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3768	int ret = VM_FAULT_FALLBACK;
3769	if (!vma->vm_ops)
3770	ret = do_huge_pmd_anonymous_page(mm, vma, address,
3771	pmd, flags);
3772	if (!(ret & VM_FAULT_FALLBACK))
3773	return ret;
3774	} else {
3775	pmd_t orig_pmd = *pmd;
3776	int ret;
3777
3778	barrier();
3779	if (pmd_trans_huge(orig_pmd)) {
3780	unsigned int dirty = flags & FAULT_FLAG_WRITE;
3781
3782	/*
3783	* If the pmd is splitting, return and retry the
3784	* the fault. Alternative: wait until the split
3785	* is done, and goto retry.
3786	*/
3787	if (pmd_trans_splitting(orig_pmd))
3788	return 0;
3789
3790	if (pmd_numa(orig_pmd))
3791	return do_huge_pmd_numa_page(mm, vma, address,
3792	orig_pmd, pmd);
3793
3794	if (dirty && !pmd_write(orig_pmd)) {
3795	ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
3796	orig_pmd);
3797	/*
3798	* If COW results in an oom, the huge pmd will
3799	* have been split, so retry the fault on the
3800	* pte for a smaller charge.
3801	*/
3802	if (unlikely(ret & VM_FAULT_OOM))
3803	goto retry;
3804	return ret;
3805	} else {
3806	huge_pmd_set_accessed(mm, vma, address, pmd,
3807	orig_pmd, dirty);
3808	}
3809
3810	return 0;
3811	}
3812	}
3813
3814	if (pmd_numa(*pmd))
3815	return do_pmd_numa_page(mm, vma, address, pmd);
3816
3817	/*
3818	* Use __pte_alloc instead of pte_alloc_map, because we can't
3819	* run pte_offset_map on the pmd, if an huge pmd could
3820	* materialize from under us from a different thread.
3821	*/
3822	if (unlikely(pmd_none(*pmd)) &&
3823	unlikely(__pte_alloc(mm, vma, pmd, address)))
3824	return VM_FAULT_OOM;
3825	/* if an huge pmd materialized from under us just retry later */
3826	if (unlikely(pmd_trans_huge(*pmd)))
3827	return 0;
3828	/*
3829	* A regular pmd is established and it can't morph into a huge pmd
3830	* from under us anymore at this point because we hold the mmap_sem
3831	* read mode and khugepaged takes it in write mode. So now it's
3832	* safe to run pte_offset_map().
3833	*/
3834	pte = pte_offset_map(pmd, address);
3835
3836	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3837	}
3838
3839	int handle_mm_fault(struct mm_struct mm, struct vm_area_struct vma,
3840	unsigned long address, unsigned int flags)
3841	{
3842	int ret;
3843
3844	__set_current_state(TASK_RUNNING);
3845
3846	count_vm_event(PGFAULT);
3847	mem_cgroup_count_vm_event(mm, PGFAULT);
3848
3849	/* do counter updates before entering really critical section. */
3850	check_sync_rss_stat(current);
3851
3852	/*
3853	* Enable the memcg OOM handling for faults triggered in user
3854	* space. Kernel faults are handled more gracefully.
3855	*/
3856	if (flags & FAULT_FLAG_USER)
3857	mem_cgroup_oom_enable();
3858
3859	ret = __handle_mm_fault(mm, vma, address, flags);
3860
3861	if (flags & FAULT_FLAG_USER) {
3862	mem_cgroup_oom_disable();
3863	/*
3864	* The task may have entered a memcg OOM situation but
3865	* if the allocation error was handled gracefully (no
3866	* VM_FAULT_OOM), there is no need to kill anything.
3867	* Just clean up the OOM state peacefully.
3868	*/
3869	if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3870	mem_cgroup_oom_synchronize(false);
3871	}
3872
3873	return ret;
3874	}
3875
3876	#ifndef __PAGETABLE_PUD_FOLDED
3877	/*
3878	* Allocate page upper directory.
3879	* We've already handled the fast-path in-line.
3880	*/
3881	int __pud_alloc(struct mm_struct mm, pgd_t pgd, unsigned long address)
3882	{
3883	pud_t *new = pud_alloc_one(mm, address);
3884	if (!new)
3885	return -ENOMEM;
3886
3887	smp_wmb(); /* See comment in __pte_alloc */
3888
3889	spin_lock(&mm->page_table_lock);
3890	if (pgd_present(pgd)) / Another has populated it */
3891	pud_free(mm, new);
3892	else
3893	pgd_populate(mm, pgd, new);
3894	spin_unlock(&mm->page_table_lock);
3895	return 0;
3896	}
3897	#endif /* __PAGETABLE_PUD_FOLDED */
3898
3899	#ifndef __PAGETABLE_PMD_FOLDED
3900	/*
3901	* Allocate page middle directory.
3902	* We've already handled the fast-path in-line.
3903	*/
3904	int __pmd_alloc(struct mm_struct mm, pud_t pud, unsigned long address)
3905	{
3906	pmd_t *new = pmd_alloc_one(mm, address);
3907	if (!new)
3908	return -ENOMEM;
3909
3910	smp_wmb(); /* See comment in __pte_alloc */
3911
3912	spin_lock(&mm->page_table_lock);
3913	#ifndef __ARCH_HAS_4LEVEL_HACK
3914	if (pud_present(pud)) / Another has populated it */
3915	pmd_free(mm, new);
3916	else
3917	pud_populate(mm, pud, new);
3918	#else
3919	if (pgd_present(pud)) / Another has populated it */
3920	pmd_free(mm, new);
3921	else
3922	pgd_populate(mm, pud, new);
3923	#endif /* __ARCH_HAS_4LEVEL_HACK */
3924	spin_unlock(&mm->page_table_lock);
3925	return 0;
3926	}
3927	#endif /* __PAGETABLE_PMD_FOLDED */
3928
3929	#if !defined(__HAVE_ARCH_GATE_AREA)
3930
3931	#if defined(AT_SYSINFO_EHDR)
3932	static struct vm_area_struct gate_vma;
3933
3934	static int __init gate_vma_init(void)
3935	{
3936	gate_vma.vm_mm = NULL;
3937	gate_vma.vm_start = FIXADDR_USER_START;
3938	gate_vma.vm_end = FIXADDR_USER_END;
3939	gate_vma.vm_flags = VM_READ \| VM_MAYREAD \| VM_EXEC \| VM_MAYEXEC;
3940	gate_vma.vm_page_prot = __P101;
3941
3942	return 0;
3943	}
3944	__initcall(gate_vma_init);
3945	#endif
3946
3947	struct vm_area_struct get_gate_vma(struct mm_struct mm)
3948	{
3949	#ifdef AT_SYSINFO_EHDR
3950	return &gate_vma;
3951	#else
3952	return NULL;
3953	#endif
3954	}
3955
3956	int in_gate_area_no_mm(unsigned long addr)
3957	{
3958	#ifdef AT_SYSINFO_EHDR
3959	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3960	return 1;
3961	#endif
3962	return 0;
3963	}
3964
3965	#endif /* __HAVE_ARCH_GATE_AREA */
3966
3967	static int __follow_pte(struct mm_struct *mm, unsigned long address,
3968	pte_t ptepp, spinlock_t ptlp)
3969	{
3970	pgd_t *pgd;
3971	pud_t *pud;
3972	pmd_t *pmd;
3973	pte_t *ptep;
3974
3975	pgd = pgd_offset(mm, address);
3976	if (pgd_none(pgd) \|\| unlikely(pgd_bad(pgd)))
3977	goto out;
3978
3979	pud = pud_offset(pgd, address);
3980	if (pud_none(pud) \|\| unlikely(pud_bad(pud)))
3981	goto out;
3982
3983	pmd = pmd_offset(pud, address);
3984	VM_BUG_ON(pmd_trans_huge(*pmd));
3985	if (pmd_none(pmd) \|\| unlikely(pmd_bad(pmd)))
3986	goto out;
3987
3988	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
3989	if (pmd_huge(*pmd))
3990	goto out;
3991
3992	ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3993	if (!ptep)
3994	goto out;
3995	if (!pte_present(*ptep))
3996	goto unlock;
3997	*ptepp = ptep;
3998	return 0;
3999	unlock:
4000	pte_unmap_unlock(ptep, *ptlp);
4001	out:
4002	return -EINVAL;
4003	}
4004
4005	static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4006	pte_t ptepp, spinlock_t ptlp)
4007	{
4008	int res;
4009
4010	/* (void) is needed to make gcc happy */
4011	(void) __cond_lock(*ptlp,
4012	!(res = __follow_pte(mm, address, ptepp, ptlp)));
4013	return res;
4014	}
4015
4016	/**
4017	* follow_pfn - look up PFN at a user virtual address
4018	* @vma: memory mapping
4019	* @address: user virtual address
4020	* @pfn: location to store found PFN
4021	*
4022	* Only IO mappings and raw PFN mappings are allowed.
4023	*
4024	* Returns zero and the pfn at @pfn on success, -ve otherwise.
4025	*/
4026	int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4027	unsigned long *pfn)
4028	{
4029	int ret = -EINVAL;
4030	spinlock_t *ptl;
4031	pte_t *ptep;
4032
4033	if (!(vma->vm_flags & (VM_IO \| VM_PFNMAP)))
4034	return ret;
4035
4036	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4037	if (ret)
4038	return ret;
4039	pfn = pte_pfn(ptep);
4040	pte_unmap_unlock(ptep, ptl);
4041	return 0;
4042	}
4043	EXPORT_SYMBOL(follow_pfn);
4044
4045	#ifdef CONFIG_HAVE_IOREMAP_PROT
4046	int follow_phys(struct vm_area_struct *vma,
4047	unsigned long address, unsigned int flags,
4048	unsigned long prot, resource_size_t phys)
4049	{
4050	int ret = -EINVAL;
4051	pte_t *ptep, pte;
4052	spinlock_t *ptl;
4053
4054	if (!(vma->vm_flags & (VM_IO \| VM_PFNMAP)))
4055	goto out;
4056
4057	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4058	goto out;
4059	pte = *ptep;
4060
4061	if ((flags & FOLL_WRITE) && !pte_write(pte))
4062	goto unlock;
4063
4064	*prot = pgprot_val(pte_pgprot(pte));
4065	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4066
4067	ret = 0;
4068	unlock:
4069	pte_unmap_unlock(ptep, ptl);
4070	out:
4071	return ret;
4072	}
4073
4074	int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4075	void *buf, int len, int write)
4076	{
4077	resource_size_t phys_addr;
4078	unsigned long prot = 0;
4079	void __iomem *maddr;
4080	int offset = addr & (PAGE_SIZE-1);
4081
4082	if (follow_phys(vma, addr, write, &prot, &phys_addr))
4083	return -EINVAL;
4084
4085	maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
4086	if (write)
4087	memcpy_toio(maddr + offset, buf, len);
4088	else
4089	memcpy_fromio(buf, maddr + offset, len);
4090	iounmap(maddr);
4091
4092	return len;
4093	}
4094	EXPORT_SYMBOL_GPL(generic_access_phys);
4095	#endif
4096
4097	/*
4098	* Access another process' address space as given in mm. If non-NULL, use the
4099	* given task for page fault accounting.
4100	*/
4101	static int __access_remote_vm(struct task_struct tsk, struct mm_struct mm,
4102	unsigned long addr, void *buf, int len, int write)
4103	{
4104	struct vm_area_struct *vma;
4105	void *old_buf = buf;
4106
4107	down_read(&mm->mmap_sem);
4108	/* ignore errors, just check how much was successfully transferred */
4109	while (len) {
4110	int bytes, ret, offset;
4111	void *maddr;
4112	struct page *page = NULL;
4113
4114	ret = get_user_pages(tsk, mm, addr, 1,
4115	write, 1, &page, &vma);
4116	if (ret <= 0) {
4117	/*
4118	* Check if this is a VM_IO \| VM_PFNMAP VMA, which
4119	* we can access using slightly different code.
4120	*/
4121	#ifdef CONFIG_HAVE_IOREMAP_PROT
4122	vma = find_vma(mm, addr);
4123	if (!vma \|\| vma->vm_start > addr)
4124	break;
4125	if (vma->vm_ops && vma->vm_ops->access)
4126	ret = vma->vm_ops->access(vma, addr, buf,
4127	len, write);
4128	if (ret <= 0)
4129	#endif
4130	break;
4131	bytes = ret;
4132	} else {
4133	bytes = len;
4134	offset = addr & (PAGE_SIZE-1);
4135	if (bytes > PAGE_SIZE-offset)
4136	bytes = PAGE_SIZE-offset;
4137
4138	maddr = kmap(page);
4139	if (write) {
4140	copy_to_user_page(vma, page, addr,
4141	maddr + offset, buf, bytes);
4142	set_page_dirty_lock(page);
4143	} else {
4144	copy_from_user_page(vma, page, addr,
4145	buf, maddr + offset, bytes);
4146	}
4147	kunmap(page);
4148	page_cache_release(page);
4149	}
4150	len -= bytes;
4151	buf += bytes;
4152	addr += bytes;
4153	}
4154	up_read(&mm->mmap_sem);
4155
4156	return buf - old_buf;
4157	}
4158
4159	/**
4160	* access_remote_vm - access another process' address space
4161	* @mm: the mm_struct of the target address space
4162	* @addr: start address to access
4163	* @buf: source or destination buffer
4164	* @len: number of bytes to transfer
4165	* @write: whether the access is a write
4166	*
4167	* The caller must hold a reference on @mm.
4168	*/
4169	int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4170	void *buf, int len, int write)
4171	{
4172	return __access_remote_vm(NULL, mm, addr, buf, len, write);
4173	}
4174
4175	/*
4176	* Access another process' address space.
4177	* Source/target buffer must be kernel space,
4178	* Do not walk the page table directly, use get_user_pages
4179	*/
4180	int access_process_vm(struct task_struct *tsk, unsigned long addr,
4181	void *buf, int len, int write)
4182	{
4183	struct mm_struct *mm;
4184	int ret;
4185
4186	mm = get_task_mm(tsk);
4187	if (!mm)
4188	return 0;
4189
4190	ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
4191	mmput(mm);
4192
4193	return ret;
4194	}
4195
4196	/*
4197	* Print the name of a VMA.
4198	*/
4199	void print_vma_addr(char *prefix, unsigned long ip)
4200	{
4201	struct mm_struct *mm = current->mm;
4202	struct vm_area_struct *vma;
4203
4204	/*
4205	* Do not print if we are in atomic
4206	* contexts (in exception stacks, etc.):
4207	*/
4208	if (preempt_count())
4209	return;
4210
4211	down_read(&mm->mmap_sem);
4212	vma = find_vma(mm, ip);
4213	if (vma && vma->vm_file) {
4214	struct file *f = vma->vm_file;
4215	char buf = (char )__get_free_page(GFP_KERNEL);
4216	if (buf) {
4217	char *p;
4218
4219	p = d_path(&f->f_path, buf, PAGE_SIZE);
4220	if (IS_ERR(p))
4221	p = "?";
4222	printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4223	vma->vm_start,
4224	vma->vm_end - vma->vm_start);
4225	free_page((unsigned long)buf);
4226	}
4227	}
4228	up_read(&mm->mmap_sem);
4229	}
4230
4231	#if defined(CONFIG_PROVE_LOCKING) \|\| defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4232	void might_fault(void)
4233	{
4234	/*
4235	* Some code (nfs/sunrpc) uses socket ops on kernel memory while
4236	* holding the mmap_sem, this is safe because kernel memory doesn't
4237	* get paged out, therefore we'll never actually fault, and the
4238	* below annotations will generate false positives.
4239	*/
4240	if (segment_eq(get_fs(), KERNEL_DS))
4241	return;
4242
4243	/*
4244	* it would be nicer only to annotate paths which are not under
4245	* pagefault_disable, however that requires a larger audit and
4246	* providing helpers like get_user_atomic.
4247	*/
4248	if (in_atomic())
4249	return;
4250
4251	__might_sleep(__FILE__, __LINE__, 0);
4252
4253	if (current->mm)
4254	might_lock_read(&current->mm->mmap_sem);
4255	}
4256	EXPORT_SYMBOL(might_fault);
4257	#endif
4258
4259	#if defined(CONFIG_TRANSPARENT_HUGEPAGE) \|\| defined(CONFIG_HUGETLBFS)
4260	static void clear_gigantic_page(struct page *page,
4261	unsigned long addr,
4262	unsigned int pages_per_huge_page)
4263	{
4264	int i;
4265	struct page *p = page;
4266
4267	might_sleep();
4268	for (i = 0; i < pages_per_huge_page;
4269	i++, p = mem_map_next(p, page, i)) {
4270	cond_resched();
4271	clear_user_highpage(p, addr + i * PAGE_SIZE);
4272	}
4273	}
4274	void clear_huge_page(struct page *page,
4275	unsigned long addr, unsigned int pages_per_huge_page)
4276	{
4277	int i;
4278
4279	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4280	clear_gigantic_page(page, addr, pages_per_huge_page);
4281	return;
4282	}
4283
4284	might_sleep();
4285	for (i = 0; i < pages_per_huge_page; i++) {
4286	cond_resched();
4287	clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4288	}
4289	}
4290
4291	static void copy_user_gigantic_page(struct page dst, struct page src,
4292	unsigned long addr,
4293	struct vm_area_struct *vma,
4294	unsigned int pages_per_huge_page)
4295	{
4296	int i;
4297	struct page *dst_base = dst;
4298	struct page *src_base = src;
4299
4300	for (i = 0; i < pages_per_huge_page; ) {
4301	cond_resched();
4302	copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4303
4304	i++;
4305	dst = mem_map_next(dst, dst_base, i);
4306	src = mem_map_next(src, src_base, i);
4307	}
4308	}
4309
4310	void copy_user_huge_page(struct page dst, struct page src,
4311	unsigned long addr, struct vm_area_struct *vma,
4312	unsigned int pages_per_huge_page)
4313	{
4314	int i;
4315
4316	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4317	copy_user_gigantic_page(dst, src, addr, vma,
4318	pages_per_huge_page);
4319	return;
4320	}
4321
4322	might_sleep();
4323	for (i = 0; i < pages_per_huge_page; i++) {
4324	cond_resched();
4325	copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4326	}
4327	}
4328	#endif /* CONFIG_TRANSPARENT_HUGEPAGE \|\| CONFIG_HUGETLBFS */
4329

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