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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
61	#include <asm/io.h>
62	#include <asm/pgalloc.h>
63	#include <asm/uaccess.h>
64	#include <asm/tlb.h>
65	#include <asm/tlbflush.h>
66	#include <asm/pgtable.h>
67
68	#include "internal.h"
69
70	#ifndef CONFIG_NEED_MULTIPLE_NODES
71	/* use the per-pgdat data instead for discontigmem - mbligh */
72	unsigned long max_mapnr;
73	struct page *mem_map;
74
75	EXPORT_SYMBOL(max_mapnr);
76	EXPORT_SYMBOL(mem_map);
77	#endif
78
79	unsigned long num_physpages;
80	/*
81	* A number of key systems in x86 including ioremap() rely on the assumption
82	* that high_memory defines the upper bound on direct map memory, then end
83	* of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
84	* highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
85	* and ZONE_HIGHMEM.
86	*/
87	void * high_memory;
88
89	EXPORT_SYMBOL(num_physpages);
90	EXPORT_SYMBOL(high_memory);
91
92	/*
93	* Randomize the address space (stacks, mmaps, brk, etc.).
94	*
95	* ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
96	* as ancient (libc5 based) binaries can segfault. )
97	*/
98	int randomize_va_space __read_mostly =
99	#ifdef CONFIG_COMPAT_BRK
100	1;
101	#else
102	2;
103	#endif
104
105	static int __init disable_randmaps(char *s)
106	{
107	randomize_va_space = 0;
108	return 1;
109	}
110	__setup("norandmaps", disable_randmaps);
111
112	unsigned long zero_pfn __read_mostly;
113	unsigned long highest_memmap_pfn __read_mostly;
114
115	/*
116	* CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
117	*/
118	static int __init init_zero_pfn(void)
119	{
120	zero_pfn = page_to_pfn(ZERO_PAGE(0));
121	return 0;
122	}
123	core_initcall(init_zero_pfn);
124
125
126	#if defined(SPLIT_RSS_COUNTING)
127
128	void sync_mm_rss(struct mm_struct *mm)
129	{
130	int i;
131
132	for (i = 0; i < NR_MM_COUNTERS; i++) {
133	if (current->rss_stat.count[i]) {
134	add_mm_counter(mm, i, current->rss_stat.count[i]);
135	current->rss_stat.count[i] = 0;
136	}
137	}
138	current->rss_stat.events = 0;
139	}
140
141	static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
142	{
143	struct task_struct *task = current;
144
145	if (likely(task->mm == mm))
146	task->rss_stat.count[member] += val;
147	else
148	add_mm_counter(mm, member, val);
149	}
150	#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
151	#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
152
153	/* sync counter once per 64 page faults */
154	#define TASK_RSS_EVENTS_THRESH (64)
155	static void check_sync_rss_stat(struct task_struct *task)
156	{
157	if (unlikely(task != current))
158	return;
159	if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
160	sync_mm_rss(task->mm);
161	}
162	#else /* SPLIT_RSS_COUNTING */
163
164	#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
165	#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
166
167	static void check_sync_rss_stat(struct task_struct *task)
168	{
169	}
170
171	#endif /* SPLIT_RSS_COUNTING */
172
173	#ifdef HAVE_GENERIC_MMU_GATHER
174
175	static int tlb_next_batch(struct mmu_gather *tlb)
176	{
177	struct mmu_gather_batch *batch;
178
179	batch = tlb->active;
180	if (batch->next) {
181	tlb->active = batch->next;
182	return 1;
183	}
184
185	batch = (void *)__get_free_pages(GFP_NOWAIT \| __GFP_NOWARN, 0);
186	if (!batch)
187	return 0;
188
189	batch->next = NULL;
190	batch->nr = 0;
191	batch->max = MAX_GATHER_BATCH;
192
193	tlb->active->next = batch;
194	tlb->active = batch;
195
196	return 1;
197	}
198
199	/* tlb_gather_mmu
200	* Called to initialize an (on-stack) mmu_gather structure for page-table
201	* tear-down from @mm. The @fullmm argument is used when @mm is without
202	* users and we're going to destroy the full address space (exit/execve).
203	*/
204	void tlb_gather_mmu(struct mmu_gather tlb, struct mm_struct mm, bool fullmm)
205	{
206	tlb->mm = mm;
207
208	tlb->fullmm = fullmm;
209	tlb->start = -1UL;
210	tlb->end = 0;
211	tlb->need_flush = 0;
212	tlb->fast_mode = (num_possible_cpus() == 1);
213	tlb->local.next = NULL;
214	tlb->local.nr = 0;
215	tlb->local.max = ARRAY_SIZE(tlb->__pages);
216	tlb->active = &tlb->local;
217
218	#ifdef CONFIG_HAVE_RCU_TABLE_FREE
219	tlb->batch = NULL;
220	#endif
221	}
222
223	void tlb_flush_mmu(struct mmu_gather *tlb)
224	{
225	struct mmu_gather_batch *batch;
226
227	if (!tlb->need_flush)
228	return;
229	tlb->need_flush = 0;
230	tlb_flush(tlb);
231	#ifdef CONFIG_HAVE_RCU_TABLE_FREE
232	tlb_table_flush(tlb);
233	#endif
234
235	if (tlb_fast_mode(tlb))
236	return;
237
238	for (batch = &tlb->local; batch; batch = batch->next) {
239	free_pages_and_swap_cache(batch->pages, batch->nr);
240	batch->nr = 0;
241	}
242	tlb->active = &tlb->local;
243	}
244
245	/* tlb_finish_mmu
246	* Called at the end of the shootdown operation to free up any resources
247	* that were required.
248	*/
249	void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
250	{
251	struct mmu_gather_batch batch, next;
252
253	tlb->start = start;
254	tlb->end = end;
255	tlb_flush_mmu(tlb);
256
257	/* keep the page table cache within bounds */
258	check_pgt_cache();
259
260	for (batch = tlb->local.next; batch; batch = next) {
261	next = batch->next;
262	free_pages((unsigned long)batch, 0);
263	}
264	tlb->local.next = NULL;
265	}
266
267	/* __tlb_remove_page
268	* Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
269	* handling the additional races in SMP caused by other CPUs caching valid
270	* mappings in their TLBs. Returns the number of free page slots left.
271	* When out of page slots we must call tlb_flush_mmu().
272	*/
273	int __tlb_remove_page(struct mmu_gather tlb, struct page page)
274	{
275	struct mmu_gather_batch *batch;
276
277	VM_BUG_ON(!tlb->need_flush);
278
279	if (tlb_fast_mode(tlb)) {
280	free_page_and_swap_cache(page);
281	return 1; /* avoid calling tlb_flush_mmu() */
282	}
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	* If a p?d_bad entry is found while walking page tables, report
377	* the error, before resetting entry to p?d_none. Usually (but
378	* very seldom) called out from the p?d_none_or_clear_bad macros.
379	*/
380
381	void pgd_clear_bad(pgd_t *pgd)
382	{
383	pgd_ERROR(*pgd);
384	pgd_clear(pgd);
385	}
386
387	void pud_clear_bad(pud_t *pud)
388	{
389	pud_ERROR(*pud);
390	pud_clear(pud);
391	}
392
393	void pmd_clear_bad(pmd_t *pmd)
394	{
395	pmd_ERROR(*pmd);
396	pmd_clear(pmd);
397	}
398
399	/*
400	* Note: this doesn't free the actual pages themselves. That
401	* has been handled earlier when unmapping all the memory regions.
402	*/
403	static void free_pte_range(struct mmu_gather tlb, pmd_t pmd,
404	unsigned long addr)
405	{
406	pgtable_t token = pmd_pgtable(*pmd);
407	pmd_clear(pmd);
408	pte_free_tlb(tlb, token, addr);
409	tlb->mm->nr_ptes--;
410	}
411
412	static inline void free_pmd_range(struct mmu_gather tlb, pud_t pud,
413	unsigned long addr, unsigned long end,
414	unsigned long floor, unsigned long ceiling)
415	{
416	pmd_t *pmd;
417	unsigned long next;
418	unsigned long start;
419
420	start = addr;
421	pmd = pmd_offset(pud, addr);
422	do {
423	next = pmd_addr_end(addr, end);
424	if (pmd_none_or_clear_bad(pmd))
425	continue;
426	free_pte_range(tlb, pmd, addr);
427	} while (pmd++, addr = next, addr != end);
428
429	start &= PUD_MASK;
430	if (start < floor)
431	return;
432	if (ceiling) {
433	ceiling &= PUD_MASK;
434	if (!ceiling)
435	return;
436	}
437	if (end - 1 > ceiling - 1)
438	return;
439
440	pmd = pmd_offset(pud, start);
441	pud_clear(pud);
442	pmd_free_tlb(tlb, pmd, start);
443	}
444
445	static inline void free_pud_range(struct mmu_gather tlb, pgd_t pgd,
446	unsigned long addr, unsigned long end,
447	unsigned long floor, unsigned long ceiling)
448	{
449	pud_t *pud;
450	unsigned long next;
451	unsigned long start;
452
453	start = addr;
454	pud = pud_offset(pgd, addr);
455	do {
456	next = pud_addr_end(addr, end);
457	if (pud_none_or_clear_bad(pud))
458	continue;
459	free_pmd_range(tlb, pud, addr, next, floor, ceiling);
460	} while (pud++, addr = next, addr != end);
461
462	start &= PGDIR_MASK;
463	if (start < floor)
464	return;
465	if (ceiling) {
466	ceiling &= PGDIR_MASK;
467	if (!ceiling)
468	return;
469	}
470	if (end - 1 > ceiling - 1)
471	return;
472
473	pud = pud_offset(pgd, start);
474	pgd_clear(pgd);
475	pud_free_tlb(tlb, pud, start);
476	}
477
478	/*
479	* This function frees user-level page tables of a process.
480	*
481	* Must be called with pagetable lock held.
482	*/
483	void free_pgd_range(struct mmu_gather *tlb,
484	unsigned long addr, unsigned long end,
485	unsigned long floor, unsigned long ceiling)
486	{
487	pgd_t *pgd;
488	unsigned long next;
489
490	/*
491	* The next few lines have given us lots of grief...
492	*
493	* Why are we testing PMD* at this top level? Because often
494	* there will be no work to do at all, and we'd prefer not to
495	* go all the way down to the bottom just to discover that.
496	*
497	* Why all these "- 1"s? Because 0 represents both the bottom
498	* of the address space and the top of it (using -1 for the
499	* top wouldn't help much: the masks would do the wrong thing).
500	* The rule is that addr 0 and floor 0 refer to the bottom of
501	* the address space, but end 0 and ceiling 0 refer to the top
502	* Comparisons need to use "end - 1" and "ceiling - 1" (though
503	* that end 0 case should be mythical).
504	*
505	* Wherever addr is brought up or ceiling brought down, we must
506	* be careful to reject "the opposite 0" before it confuses the
507	* subsequent tests. But what about where end is brought down
508	* by PMD_SIZE below? no, end can't go down to 0 there.
509	*
510	* Whereas we round start (addr) and ceiling down, by different
511	* masks at different levels, in order to test whether a table
512	* now has no other vmas using it, so can be freed, we don't
513	* bother to round floor or end up - the tests don't need that.
514	*/
515
516	addr &= PMD_MASK;
517	if (addr < floor) {
518	addr += PMD_SIZE;
519	if (!addr)
520	return;
521	}
522	if (ceiling) {
523	ceiling &= PMD_MASK;
524	if (!ceiling)
525	return;
526	}
527	if (end - 1 > ceiling - 1)
528	end -= PMD_SIZE;
529	if (addr > end - 1)
530	return;
531
532	pgd = pgd_offset(tlb->mm, addr);
533	do {
534	next = pgd_addr_end(addr, end);
535	if (pgd_none_or_clear_bad(pgd))
536	continue;
537	free_pud_range(tlb, pgd, addr, next, floor, ceiling);
538	} while (pgd++, addr = next, addr != end);
539	}
540
541	void free_pgtables(struct mmu_gather tlb, struct vm_area_struct vma,
542	unsigned long floor, unsigned long ceiling)
543	{
544	while (vma) {
545	struct vm_area_struct *next = vma->vm_next;
546	unsigned long addr = vma->vm_start;
547
548	/*
549	* Hide vma from rmap and truncate_pagecache before freeing
550	* pgtables
551	*/
552	unlink_anon_vmas(vma);
553	unlink_file_vma(vma);
554
555	if (is_vm_hugetlb_page(vma)) {
556	hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
557	floor, next? next->vm_start: ceiling);
558	} else {
559	/*
560	* Optimization: gather nearby vmas into one call down
561	*/
562	while (next && next->vm_start <= vma->vm_end + PMD_SIZE
563	&& !is_vm_hugetlb_page(next)) {
564	vma = next;
565	next = vma->vm_next;
566	unlink_anon_vmas(vma);
567	unlink_file_vma(vma);
568	}
569	free_pgd_range(tlb, addr, vma->vm_end,
570	floor, next? next->vm_start: ceiling);
571	}
572	vma = next;
573	}
574	}
575
576	int __pte_alloc(struct mm_struct mm, struct vm_area_struct vma,
577	pmd_t *pmd, unsigned long address)
578	{
579	pgtable_t new = pte_alloc_one(mm, address);
580	int wait_split_huge_page;
581	if (!new)
582	return -ENOMEM;
583
584	/*
585	* Ensure all pte setup (eg. pte page lock and page clearing) are
586	* visible before the pte is made visible to other CPUs by being
587	* put into page tables.
588	*
589	* The other side of the story is the pointer chasing in the page
590	* table walking code (when walking the page table without locking;
591	* ie. most of the time). Fortunately, these data accesses consist
592	* of a chain of data-dependent loads, meaning most CPUs (alpha
593	* being the notable exception) will already guarantee loads are
594	* seen in-order. See the alpha page table accessors for the
595	* smp_read_barrier_depends() barriers in page table walking code.
596	*/
597	smp_wmb(); /* Could be smp_wmb__xxx(before\|after)_spin_lock */
598
599	spin_lock(&mm->page_table_lock);
600	wait_split_huge_page = 0;
601	if (likely(pmd_none(pmd))) { / Has another populated it ? */
602	mm->nr_ptes++;
603	pmd_populate(mm, pmd, new);
604	new = NULL;
605	} else if (unlikely(pmd_trans_splitting(*pmd)))
606	wait_split_huge_page = 1;
607	spin_unlock(&mm->page_table_lock);
608	if (new)
609	pte_free(mm, new);
610	if (wait_split_huge_page)
611	wait_split_huge_page(vma->anon_vma, pmd);
612	return 0;
613	}
614
615	int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
616	{
617	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
618	if (!new)
619	return -ENOMEM;
620
621	smp_wmb(); /* See comment in __pte_alloc */
622
623	spin_lock(&init_mm.page_table_lock);
624	if (likely(pmd_none(pmd))) { / Has another populated it ? */
625	pmd_populate_kernel(&init_mm, pmd, new);
626	new = NULL;
627	} else
628	VM_BUG_ON(pmd_trans_splitting(*pmd));
629	spin_unlock(&init_mm.page_table_lock);
630	if (new)
631	pte_free_kernel(&init_mm, new);
632	return 0;
633	}
634
635	static inline void init_rss_vec(int *rss)
636	{
637	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
638	}
639
640	static inline void add_mm_rss_vec(struct mm_struct mm, int rss)
641	{
642	int i;
643
644	if (current->mm == mm)
645	sync_mm_rss(mm);
646	for (i = 0; i < NR_MM_COUNTERS; i++)
647	if (rss[i])
648	add_mm_counter(mm, i, rss[i]);
649	}
650
651	/*
652	* This function is called to print an error when a bad pte
653	* is found. For example, we might have a PFN-mapped pte in
654	* a region that doesn't allow it.
655	*
656	* The calling function must still handle the error.
657	*/
658	static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
659	pte_t pte, struct page *page)
660	{
661	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
662	pud_t *pud = pud_offset(pgd, addr);
663	pmd_t *pmd = pmd_offset(pud, addr);
664	struct address_space *mapping;
665	pgoff_t index;
666	static unsigned long resume;
667	static unsigned long nr_shown;
668	static unsigned long nr_unshown;
669
670	/*
671	* Allow a burst of 60 reports, then keep quiet for that minute;
672	* or allow a steady drip of one report per second.
673	*/
674	if (nr_shown == 60) {
675	if (time_before(jiffies, resume)) {
676	nr_unshown++;
677	return;
678	}
679	if (nr_unshown) {
680	printk(KERN_ALERT
681	"BUG: Bad page map: %lu messages suppressed\n",
682	nr_unshown);
683	nr_unshown = 0;
684	}
685	nr_shown = 0;
686	}
687	if (nr_shown++ == 0)
688	resume = jiffies + 60 * HZ;
689
690	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
691	index = linear_page_index(vma, addr);
692
693	printk(KERN_ALERT
694	"BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
695	current->comm,
696	(long long)pte_val(pte), (long long)pmd_val(*pmd));
697	if (page)
698	dump_page(page);
699	printk(KERN_ALERT
700	"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
701	(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
702	/*
703	* Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
704	*/
705	if (vma->vm_ops)
706	print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
707	(unsigned long)vma->vm_ops->fault);
708	if (vma->vm_file && vma->vm_file->f_op)
709	print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
710	(unsigned long)vma->vm_file->f_op->mmap);
711	dump_stack();
712	add_taint(TAINT_BAD_PAGE);
713	}
714
715	static inline int is_cow_mapping(vm_flags_t flags)
716	{
717	return (flags & (VM_SHARED \| VM_MAYWRITE)) == VM_MAYWRITE;
718	}
719
720	#ifndef is_zero_pfn
721	static inline int is_zero_pfn(unsigned long pfn)
722	{
723	return pfn == zero_pfn;
724	}
725	#endif
726
727	#ifndef my_zero_pfn
728	static inline unsigned long my_zero_pfn(unsigned long addr)
729	{
730	return zero_pfn;
731	}
732	#endif
733
734	/*
735	* vm_normal_page -- This function gets the "struct page" associated with a pte.
736	*
737	* "Special" mappings do not wish to be associated with a "struct page" (either
738	* it doesn't exist, or it exists but they don't want to touch it). In this
739	* case, NULL is returned here. "Normal" mappings do have a struct page.
740	*
741	* There are 2 broad cases. Firstly, an architecture may define a pte_special()
742	* pte bit, in which case this function is trivial. Secondly, an architecture
743	* may not have a spare pte bit, which requires a more complicated scheme,
744	* described below.
745	*
746	* A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
747	* special mapping (even if there are underlying and valid "struct pages").
748	* COWed pages of a VM_PFNMAP are always normal.
749	*
750	* The way we recognize COWed pages within VM_PFNMAP mappings is through the
751	* rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
752	* set, and the vm_pgoff will point to the first PFN mapped: thus every special
753	* mapping will always honor the rule
754	*
755	* pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
756	*
757	* And for normal mappings this is false.
758	*
759	* This restricts such mappings to be a linear translation from virtual address
760	* to pfn. To get around this restriction, we allow arbitrary mappings so long
761	* as the vma is not a COW mapping; in that case, we know that all ptes are
762	* special (because none can have been COWed).
763	*
764	*
765	* In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
766	*
767	* VM_MIXEDMAP mappings can likewise contain memory with or without "struct
768	* page" backing, however the difference is that _all_ pages with a struct
769	* page (that is, those where pfn_valid is true) are refcounted and considered
770	* normal pages by the VM. The disadvantage is that pages are refcounted
771	* (which can be slower and simply not an option for some PFNMAP users). The
772	* advantage is that we don't have to follow the strict linearity rule of
773	* PFNMAP mappings in order to support COWable mappings.
774	*
775	*/
776	#ifdef __HAVE_ARCH_PTE_SPECIAL
777	# define HAVE_PTE_SPECIAL 1
778	#else
779	# define HAVE_PTE_SPECIAL 0
780	#endif
781	struct page vm_normal_page(struct vm_area_struct vma, unsigned long addr,
782	pte_t pte)
783	{
784	unsigned long pfn = pte_pfn(pte);
785
786	if (HAVE_PTE_SPECIAL) {
787	if (likely(!pte_special(pte)))
788	goto check_pfn;
789	if (vma->vm_flags & (VM_PFNMAP \| VM_MIXEDMAP))
790	return NULL;
791	if (!is_zero_pfn(pfn))
792	print_bad_pte(vma, addr, pte, NULL);
793	return NULL;
794	}
795
796	/* !HAVE_PTE_SPECIAL case follows: */
797
798	if (unlikely(vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP))) {
799	if (vma->vm_flags & VM_MIXEDMAP) {
800	if (!pfn_valid(pfn))
801	return NULL;
802	goto out;
803	} else {
804	unsigned long off;
805	off = (addr - vma->vm_start) >> PAGE_SHIFT;
806	if (pfn == vma->vm_pgoff + off)
807	return NULL;
808	if (!is_cow_mapping(vma->vm_flags))
809	return NULL;
810	}
811	}
812
813	if (is_zero_pfn(pfn))
814	return NULL;
815	check_pfn:
816	if (unlikely(pfn > highest_memmap_pfn)) {
817	print_bad_pte(vma, addr, pte, NULL);
818	return NULL;
819	}
820
821	/*
822	* NOTE! We still have PageReserved() pages in the page tables.
823	* eg. VDSO mappings can cause them to exist.
824	*/
825	out:
826	return pfn_to_page(pfn);
827	}
828
829	/*
830	* copy one vm_area from one task to the other. Assumes the page tables
831	* already present in the new task to be cleared in the whole range
832	* covered by this vma.
833	*/
834
835	static inline unsigned long
836	copy_one_pte(struct mm_struct dst_mm, struct mm_struct src_mm,
837	pte_t dst_pte, pte_t src_pte, struct vm_area_struct *vma,
838	unsigned long addr, int *rss)
839	{
840	unsigned long vm_flags = vma->vm_flags;
841	pte_t pte = *src_pte;
842	struct page *page;
843
844	/* pte contains position in swap or file, so copy. */
845	if (unlikely(!pte_present(pte))) {
846	if (!pte_file(pte)) {
847	swp_entry_t entry = pte_to_swp_entry(pte);
848
849	if (swap_duplicate(entry) < 0)
850	return entry.val;
851
852	/* make sure dst_mm is on swapoff's mmlist. */
853	if (unlikely(list_empty(&dst_mm->mmlist))) {
854	spin_lock(&mmlist_lock);
855	if (list_empty(&dst_mm->mmlist))
856	list_add(&dst_mm->mmlist,
857	&src_mm->mmlist);
858	spin_unlock(&mmlist_lock);
859	}
860	if (likely(!non_swap_entry(entry)))
861	rss[MM_SWAPENTS]++;
862	else if (is_migration_entry(entry)) {
863	page = migration_entry_to_page(entry);
864
865	if (PageAnon(page))
866	rss[MM_ANONPAGES]++;
867	else
868	rss[MM_FILEPAGES]++;
869
870	if (is_write_migration_entry(entry) &&
871	is_cow_mapping(vm_flags)) {
872	/*
873	* COW mappings require pages in both
874	* parent and child to be set to read.
875	*/
876	make_migration_entry_read(&entry);
877	pte = swp_entry_to_pte(entry);
878	set_pte_at(src_mm, addr, src_pte, pte);
879	}
880	}
881	}
882	goto out_set_pte;
883	}
884
885	/*
886	* If it's a COW mapping, write protect it both
887	* in the parent and the child
888	*/
889	if (is_cow_mapping(vm_flags)) {
890	ptep_set_wrprotect(src_mm, addr, src_pte);
891	pte = pte_wrprotect(pte);
892	}
893
894	/*
895	* If it's a shared mapping, mark it clean in
896	* the child
897	*/
898	if (vm_flags & VM_SHARED)
899	pte = pte_mkclean(pte);
900	pte = pte_mkold(pte);
901
902	page = vm_normal_page(vma, addr, pte);
903	if (page) {
904	get_page(page);
905	page_dup_rmap(page);
906	if (PageAnon(page))
907	rss[MM_ANONPAGES]++;
908	else
909	rss[MM_FILEPAGES]++;
910	}
911
912	out_set_pte:
913	set_pte_at(dst_mm, addr, dst_pte, pte);
914	return 0;
915	}
916
917	int copy_pte_range(struct mm_struct dst_mm, struct mm_struct src_mm,
918	pmd_t dst_pmd, pmd_t src_pmd, struct vm_area_struct *vma,
919	unsigned long addr, unsigned long end)
920	{
921	pte_t orig_src_pte, orig_dst_pte;
922	pte_t src_pte, dst_pte;
923	spinlock_t src_ptl, dst_ptl;
924	int progress = 0;
925	int rss[NR_MM_COUNTERS];
926	swp_entry_t entry = (swp_entry_t){0};
927
928	again:
929	init_rss_vec(rss);
930
931	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
932	if (!dst_pte)
933	return -ENOMEM;
934	src_pte = pte_offset_map(src_pmd, addr);
935	src_ptl = pte_lockptr(src_mm, src_pmd);
936	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
937	orig_src_pte = src_pte;
938	orig_dst_pte = dst_pte;
939	arch_enter_lazy_mmu_mode();
940
941	do {
942	/*
943	* We are holding two locks at this point - either of them
944	* could generate latencies in another task on another CPU.
945	*/
946	if (progress >= 32) {
947	progress = 0;
948	if (need_resched() \|\|
949	spin_needbreak(src_ptl) \|\| spin_needbreak(dst_ptl))
950	break;
951	}
952	if (pte_none(*src_pte)) {
953	progress++;
954	continue;
955	}
956	entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
957	vma, addr, rss);
958	if (entry.val)
959	break;
960	progress += 8;
961	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
962
963	arch_leave_lazy_mmu_mode();
964	spin_unlock(src_ptl);
965	pte_unmap(orig_src_pte);
966	add_mm_rss_vec(dst_mm, rss);
967	pte_unmap_unlock(orig_dst_pte, dst_ptl);
968	cond_resched();
969
970	if (entry.val) {
971	if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
972	return -ENOMEM;
973	progress = 0;
974	}
975	if (addr != end)
976	goto again;
977	return 0;
978	}
979
980	static inline int copy_pmd_range(struct mm_struct dst_mm, struct mm_struct src_mm,
981	pud_t dst_pud, pud_t src_pud, struct vm_area_struct *vma,
982	unsigned long addr, unsigned long end)
983	{
984	pmd_t src_pmd, dst_pmd;
985	unsigned long next;
986
987	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
988	if (!dst_pmd)
989	return -ENOMEM;
990	src_pmd = pmd_offset(src_pud, addr);
991	do {
992	next = pmd_addr_end(addr, end);
993	if (pmd_trans_huge(*src_pmd)) {
994	int err;
995	VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
996	err = copy_huge_pmd(dst_mm, src_mm,
997	dst_pmd, src_pmd, addr, vma);
998	if (err == -ENOMEM)
999	return -ENOMEM;
1000	if (!err)
1001	continue;
1002	/* fall through */
1003	}
1004	if (pmd_none_or_clear_bad(src_pmd))
1005	continue;
1006	if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1007	vma, addr, next))
1008	return -ENOMEM;
1009	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
1010	return 0;
1011	}
1012
1013	static inline int copy_pud_range(struct mm_struct dst_mm, struct mm_struct src_mm,
1014	pgd_t dst_pgd, pgd_t src_pgd, struct vm_area_struct *vma,
1015	unsigned long addr, unsigned long end)
1016	{
1017	pud_t src_pud, dst_pud;
1018	unsigned long next;
1019
1020	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1021	if (!dst_pud)
1022	return -ENOMEM;
1023	src_pud = pud_offset(src_pgd, addr);
1024	do {
1025	next = pud_addr_end(addr, end);
1026	if (pud_none_or_clear_bad(src_pud))
1027	continue;
1028	if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1029	vma, addr, next))
1030	return -ENOMEM;
1031	} while (dst_pud++, src_pud++, addr = next, addr != end);
1032	return 0;
1033	}
1034
1035	int copy_page_range(struct mm_struct dst_mm, struct mm_struct src_mm,
1036	struct vm_area_struct *vma)
1037	{
1038	pgd_t src_pgd, dst_pgd;
1039	unsigned long next;
1040	unsigned long addr = vma->vm_start;
1041	unsigned long end = vma->vm_end;
1042	int ret;
1043
1044	/*
1045	* Don't copy ptes where a page fault will fill them correctly.
1046	* Fork becomes much lighter when there are big shared or private
1047	* readonly mappings. The tradeoff is that copy_page_range is more
1048	* efficient than faulting.
1049	*/
1050	if (!(vma->vm_flags & (VM_HUGETLB\|VM_NONLINEAR\|VM_PFNMAP\|VM_INSERTPAGE))) {
1051	if (!vma->anon_vma)
1052	return 0;
1053	}
1054
1055	if (is_vm_hugetlb_page(vma))
1056	return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1057
1058	if (unlikely(is_pfn_mapping(vma))) {
1059	/*
1060	* We do not free on error cases below as remove_vma
1061	* gets called on error from higher level routine
1062	*/
1063	ret = track_pfn_vma_copy(vma);
1064	if (ret)
1065	return ret;
1066	}
1067
1068	/*
1069	* We need to invalidate the secondary MMU mappings only when
1070	* there could be a permission downgrade on the ptes of the
1071	* parent mm. And a permission downgrade will only happen if
1072	* is_cow_mapping() returns true.
1073	*/
1074	if (is_cow_mapping(vma->vm_flags))
1075	mmu_notifier_invalidate_range_start(src_mm, addr, end);
1076
1077	ret = 0;
1078	dst_pgd = pgd_offset(dst_mm, addr);
1079	src_pgd = pgd_offset(src_mm, addr);
1080	do {
1081	next = pgd_addr_end(addr, end);
1082	if (pgd_none_or_clear_bad(src_pgd))
1083	continue;
1084	if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1085	vma, addr, next))) {
1086	ret = -ENOMEM;
1087	break;
1088	}
1089	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
1090
1091	if (is_cow_mapping(vma->vm_flags))
1092	mmu_notifier_invalidate_range_end(src_mm,
1093	vma->vm_start, end);
1094	return ret;
1095	}
1096
1097	static unsigned long zap_pte_range(struct mmu_gather *tlb,
1098	struct vm_area_struct vma, pmd_t pmd,
1099	unsigned long addr, unsigned long end,
1100	struct zap_details *details)
1101	{
1102	struct mm_struct *mm = tlb->mm;
1103	int force_flush = 0;
1104	int rss[NR_MM_COUNTERS];
1105	spinlock_t *ptl;
1106	pte_t *start_pte;
1107	pte_t *pte;
1108
1109	again:
1110	init_rss_vec(rss);
1111	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1112	pte = start_pte;
1113	arch_enter_lazy_mmu_mode();
1114	do {
1115	pte_t ptent = *pte;
1116	if (pte_none(ptent)) {
1117	continue;
1118	}
1119
1120	if (pte_present(ptent)) {
1121	struct page *page;
1122
1123	page = vm_normal_page(vma, addr, ptent);
1124	if (unlikely(details) && page) {
1125	/*
1126	* unmap_shared_mapping_pages() wants to
1127	* invalidate cache without truncating:
1128	* unmap shared but keep private pages.
1129	*/
1130	if (details->check_mapping &&
1131	details->check_mapping != page->mapping)
1132	continue;
1133	/*
1134	* Each page->index must be checked when
1135	* invalidating or truncating nonlinear.
1136	*/
1137	if (details->nonlinear_vma &&
1138	(page->index < details->first_index \|\|
1139	page->index > details->last_index))
1140	continue;
1141	}
1142	ptent = ptep_get_and_clear_full(mm, addr, pte,
1143	tlb->fullmm);
1144	tlb_remove_tlb_entry(tlb, pte, addr);
1145	if (unlikely(!page))
1146	continue;
1147	if (unlikely(details) && details->nonlinear_vma
1148	&& linear_page_index(details->nonlinear_vma,
1149	addr) != page->index)
1150	set_pte_at(mm, addr, pte,
1151	pgoff_to_pte(page->index));
1152	if (PageAnon(page))
1153	rss[MM_ANONPAGES]--;
1154	else {
1155	if (pte_dirty(ptent))
1156	set_page_dirty(page);
1157	if (pte_young(ptent) &&
1158	likely(!VM_SequentialReadHint(vma)))
1159	mark_page_accessed(page);
1160	rss[MM_FILEPAGES]--;
1161	}
1162	page_remove_rmap(page);
1163	if (unlikely(page_mapcount(page) < 0))
1164	print_bad_pte(vma, addr, ptent, page);
1165	force_flush = !__tlb_remove_page(tlb, page);
1166	if (force_flush)
1167	break;
1168	continue;
1169	}
1170	/*
1171	* If details->check_mapping, we leave swap entries;
1172	* if details->nonlinear_vma, we leave file entries.
1173	*/
1174	if (unlikely(details))
1175	continue;
1176	if (pte_file(ptent)) {
1177	if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1178	print_bad_pte(vma, addr, ptent, NULL);
1179	} else {
1180	swp_entry_t entry = pte_to_swp_entry(ptent);
1181
1182	if (!non_swap_entry(entry))
1183	rss[MM_SWAPENTS]--;
1184	else if (is_migration_entry(entry)) {
1185	struct page *page;
1186
1187	page = migration_entry_to_page(entry);
1188
1189	if (PageAnon(page))
1190	rss[MM_ANONPAGES]--;
1191	else
1192	rss[MM_FILEPAGES]--;
1193	}
1194	if (unlikely(!free_swap_and_cache(entry)))
1195	print_bad_pte(vma, addr, ptent, NULL);
1196	}
1197	pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1198	} while (pte++, addr += PAGE_SIZE, addr != end);
1199
1200	add_mm_rss_vec(mm, rss);
1201	arch_leave_lazy_mmu_mode();
1202	pte_unmap_unlock(start_pte, ptl);
1203
1204	/*
1205	* mmu_gather ran out of room to batch pages, we break out of
1206	* the PTE lock to avoid doing the potential expensive TLB invalidate
1207	* and page-free while holding it.
1208	*/
1209	if (force_flush) {
1210	force_flush = 0;
1211
1212	#ifdef HAVE_GENERIC_MMU_GATHER
1213	tlb->start = addr;
1214	tlb->end = end;
1215	#endif
1216	tlb_flush_mmu(tlb);
1217	if (addr != end)
1218	goto again;
1219	}
1220
1221	return addr;
1222	}
1223
1224	static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1225	struct vm_area_struct vma, pud_t pud,
1226	unsigned long addr, unsigned long end,
1227	struct zap_details *details)
1228	{
1229	pmd_t *pmd;
1230	unsigned long next;
1231
1232	pmd = pmd_offset(pud, addr);
1233	do {
1234	next = pmd_addr_end(addr, end);
1235	if (pmd_trans_huge(*pmd)) {
1236	if (next - addr != HPAGE_PMD_SIZE) {
1237	#ifdef CONFIG_DEBUG_VM
1238	if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
1239	pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
1240	__func__, addr, end,
1241	vma->vm_start,
1242	vma->vm_end);
1243	BUG();
1244	}
1245	#endif
1246	split_huge_page_pmd(vma->vm_mm, pmd);
1247	} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1248	goto next;
1249	/* fall through */
1250	}
1251	/*
1252	* Here there can be other concurrent MADV_DONTNEED or
1253	* trans huge page faults running, and if the pmd is
1254	* none or trans huge it can change under us. This is
1255	* because MADV_DONTNEED holds the mmap_sem in read
1256	* mode.
1257	*/
1258	if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1259	goto next;
1260	next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1261	next:
1262	cond_resched();
1263	} while (pmd++, addr = next, addr != end);
1264
1265	return addr;
1266	}
1267
1268	static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1269	struct vm_area_struct vma, pgd_t pgd,
1270	unsigned long addr, unsigned long end,
1271	struct zap_details *details)
1272	{
1273	pud_t *pud;
1274	unsigned long next;
1275
1276	pud = pud_offset(pgd, addr);
1277	do {
1278	next = pud_addr_end(addr, end);
1279	if (pud_none_or_clear_bad(pud))
1280	continue;
1281	next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1282	} while (pud++, addr = next, addr != end);
1283
1284	return addr;
1285	}
1286
1287	static void unmap_page_range(struct mmu_gather *tlb,
1288	struct vm_area_struct *vma,
1289	unsigned long addr, unsigned long end,
1290	struct zap_details *details)
1291	{
1292	pgd_t *pgd;
1293	unsigned long next;
1294
1295	if (details && !details->check_mapping && !details->nonlinear_vma)
1296	details = NULL;
1297
1298	BUG_ON(addr >= end);
1299	mem_cgroup_uncharge_start();
1300	tlb_start_vma(tlb, vma);
1301	pgd = pgd_offset(vma->vm_mm, addr);
1302	do {
1303	next = pgd_addr_end(addr, end);
1304	if (pgd_none_or_clear_bad(pgd))
1305	continue;
1306	next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1307	} while (pgd++, addr = next, addr != end);
1308	tlb_end_vma(tlb, vma);
1309	mem_cgroup_uncharge_end();
1310	}
1311
1312
1313	static void unmap_single_vma(struct mmu_gather *tlb,
1314	struct vm_area_struct *vma, unsigned long start_addr,
1315	unsigned long end_addr,
1316	struct zap_details *details)
1317	{
1318	unsigned long start = max(vma->vm_start, start_addr);
1319	unsigned long end;
1320
1321	if (start >= vma->vm_end)
1322	return;
1323	end = min(vma->vm_end, end_addr);
1324	if (end <= vma->vm_start)
1325	return;
1326
1327	if (vma->vm_file)
1328	uprobe_munmap(vma, start, end);
1329
1330	if (unlikely(is_pfn_mapping(vma)))
1331	untrack_pfn_vma(vma, 0, 0);
1332
1333	if (start != end) {
1334	if (unlikely(is_vm_hugetlb_page(vma))) {
1335	/*
1336	* It is undesirable to test vma->vm_file as it
1337	* should be non-null for valid hugetlb area.
1338	* However, vm_file will be NULL in the error
1339	* cleanup path of do_mmap_pgoff. When
1340	* hugetlbfs ->mmap method fails,
1341	* do_mmap_pgoff() nullifies vma->vm_file
1342	* before calling this function to clean up.
1343	* Since no pte has actually been setup, it is
1344	* safe to do nothing in this case.
1345	*/
1346	if (vma->vm_file) {
1347	mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
1348	__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1349	mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
1350	}
1351	} else
1352	unmap_page_range(tlb, vma, start, end, details);
1353	}
1354	}
1355
1356	/**
1357	* unmap_vmas - unmap a range of memory covered by a list of vma's
1358	* @tlb: address of the caller's struct mmu_gather
1359	* @vma: the starting vma
1360	* @start_addr: virtual address at which to start unmapping
1361	* @end_addr: virtual address at which to end unmapping
1362	*
1363	* Unmap all pages in the vma list.
1364	*
1365	* Only addresses between `start' and `end' will be unmapped.
1366	*
1367	* The VMA list must be sorted in ascending virtual address order.
1368	*
1369	* unmap_vmas() assumes that the caller will flush the whole unmapped address
1370	* range after unmap_vmas() returns. So the only responsibility here is to
1371	* ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1372	* drops the lock and schedules.
1373	*/
1374	void unmap_vmas(struct mmu_gather *tlb,
1375	struct vm_area_struct *vma, unsigned long start_addr,
1376	unsigned long end_addr)
1377	{
1378	struct mm_struct *mm = vma->vm_mm;
1379
1380	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1381	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1382	unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1383	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1384	}
1385
1386	/**
1387	* zap_page_range - remove user pages in a given range
1388	* @vma: vm_area_struct holding the applicable pages
1389	* @start: starting address of pages to zap
1390	* @size: number of bytes to zap
1391	* @details: details of nonlinear truncation or shared cache invalidation
1392	*
1393	* Caller must protect the VMA list
1394	*/
1395	void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1396	unsigned long size, struct zap_details *details)
1397	{
1398	struct mm_struct *mm = vma->vm_mm;
1399	struct mmu_gather tlb;
1400	unsigned long end = start + size;
1401
1402	lru_add_drain();
1403	tlb_gather_mmu(&tlb, mm, 0);
1404	update_hiwater_rss(mm);
1405	mmu_notifier_invalidate_range_start(mm, start, end);
1406	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1407	unmap_single_vma(&tlb, vma, start, end, details);
1408	mmu_notifier_invalidate_range_end(mm, start, end);
1409	tlb_finish_mmu(&tlb, start, end);
1410	}
1411
1412	/**
1413	* zap_page_range_single - remove user pages in a given range
1414	* @vma: vm_area_struct holding the applicable pages
1415	* @address: starting address of pages to zap
1416	* @size: number of bytes to zap
1417	* @details: details of nonlinear truncation or shared cache invalidation
1418	*
1419	* The range must fit into one VMA.
1420	*/
1421	static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1422	unsigned long size, struct zap_details *details)
1423	{
1424	struct mm_struct *mm = vma->vm_mm;
1425	struct mmu_gather tlb;
1426	unsigned long end = address + size;
1427
1428	lru_add_drain();
1429	tlb_gather_mmu(&tlb, mm, 0);
1430	update_hiwater_rss(mm);
1431	mmu_notifier_invalidate_range_start(mm, address, end);
1432	unmap_single_vma(&tlb, vma, address, end, details);
1433	mmu_notifier_invalidate_range_end(mm, address, end);
1434	tlb_finish_mmu(&tlb, address, end);
1435	}
1436
1437	/**
1438	* zap_vma_ptes - remove ptes mapping the vma
1439	* @vma: vm_area_struct holding ptes to be zapped
1440	* @address: starting address of pages to zap
1441	* @size: number of bytes to zap
1442	*
1443	* This function only unmaps ptes assigned to VM_PFNMAP vmas.
1444	*
1445	* The entire address range must be fully contained within the vma.
1446	*
1447	* Returns 0 if successful.
1448	*/
1449	int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1450	unsigned long size)
1451	{
1452	if (address < vma->vm_start \|\| address + size > vma->vm_end \|\|
1453	!(vma->vm_flags & VM_PFNMAP))
1454	return -1;
1455	zap_page_range_single(vma, address, size, NULL);
1456	return 0;
1457	}
1458	EXPORT_SYMBOL_GPL(zap_vma_ptes);
1459
1460	/**
1461	* follow_page - look up a page descriptor from a user-virtual address
1462	* @vma: vm_area_struct mapping @address
1463	* @address: virtual address to look up
1464	* @flags: flags modifying lookup behaviour
1465	*
1466	* @flags can have FOLL_ flags set, defined in <linux/mm.h>
1467	*
1468	* Returns the mapped (struct page *), %NULL if no mapping exists, or
1469	* an error pointer if there is a mapping to something not represented
1470	* by a page descriptor (see also vm_normal_page()).
1471	*/
1472	struct page follow_page(struct vm_area_struct vma, unsigned long address,
1473	unsigned int flags)
1474	{
1475	pgd_t *pgd;
1476	pud_t *pud;
1477	pmd_t *pmd;
1478	pte_t *ptep, pte;
1479	spinlock_t *ptl;
1480	struct page *page;
1481	struct mm_struct *mm = vma->vm_mm;
1482
1483	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1484	if (!IS_ERR(page)) {
1485	BUG_ON(flags & FOLL_GET);
1486	goto out;
1487	}
1488
1489	page = NULL;
1490	pgd = pgd_offset(mm, address);
1491	if (pgd_none(pgd) \|\| unlikely(pgd_bad(pgd)))
1492	goto no_page_table;
1493
1494	pud = pud_offset(pgd, address);
1495	if (pud_none(*pud))
1496	goto no_page_table;
1497	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1498	BUG_ON(flags & FOLL_GET);
1499	page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1500	goto out;
1501	}
1502	if (unlikely(pud_bad(*pud)))
1503	goto no_page_table;
1504
1505	pmd = pmd_offset(pud, address);
1506	if (pmd_none(*pmd))
1507	goto no_page_table;
1508	if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1509	BUG_ON(flags & FOLL_GET);
1510	page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1511	goto out;
1512	}
1513	if (pmd_trans_huge(*pmd)) {
1514	if (flags & FOLL_SPLIT) {
1515	split_huge_page_pmd(mm, pmd);
1516	goto split_fallthrough;
1517	}
1518	spin_lock(&mm->page_table_lock);
1519	if (likely(pmd_trans_huge(*pmd))) {
1520	if (unlikely(pmd_trans_splitting(*pmd))) {
1521	spin_unlock(&mm->page_table_lock);
1522	wait_split_huge_page(vma->anon_vma, pmd);
1523	} else {
1524	page = follow_trans_huge_pmd(mm, address,
1525	pmd, flags);
1526	spin_unlock(&mm->page_table_lock);
1527	goto out;
1528	}
1529	} else
1530	spin_unlock(&mm->page_table_lock);
1531	/* fall through */
1532	}
1533	split_fallthrough:
1534	if (unlikely(pmd_bad(*pmd)))
1535	goto no_page_table;
1536
1537	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1538
1539	pte = *ptep;
1540	if (!pte_present(pte))
1541	goto no_page;
1542	if ((flags & FOLL_WRITE) && !pte_write(pte))
1543	goto unlock;
1544
1545	page = vm_normal_page(vma, address, pte);
1546	if (unlikely(!page)) {
1547	if ((flags & FOLL_DUMP) \|\|
1548	!is_zero_pfn(pte_pfn(pte)))
1549	goto bad_page;
1550	page = pte_page(pte);
1551	}
1552
1553	if (flags & FOLL_GET)
1554	get_page_foll(page);
1555	if (flags & FOLL_TOUCH) {
1556	if ((flags & FOLL_WRITE) &&
1557	!pte_dirty(pte) && !PageDirty(page))
1558	set_page_dirty(page);
1559	/*
1560	* pte_mkyoung() would be more correct here, but atomic care
1561	* is needed to avoid losing the dirty bit: it is easier to use
1562	* mark_page_accessed().
1563	*/
1564	mark_page_accessed(page);
1565	}
1566	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1567	/*
1568	* The preliminary mapping check is mainly to avoid the
1569	* pointless overhead of lock_page on the ZERO_PAGE
1570	* which might bounce very badly if there is contention.
1571	*
1572	* If the page is already locked, we don't need to
1573	* handle it now - vmscan will handle it later if and
1574	* when it attempts to reclaim the page.
1575	*/
1576	if (page->mapping && trylock_page(page)) {
1577	lru_add_drain(); /* push cached pages to LRU */
1578	/*
1579	* Because we lock page here and migration is
1580	* blocked by the pte's page reference, we need
1581	* only check for file-cache page truncation.
1582	*/
1583	if (page->mapping)
1584	mlock_vma_page(page);
1585	unlock_page(page);
1586	}
1587	}
1588	unlock:
1589	pte_unmap_unlock(ptep, ptl);
1590	out:
1591	return page;
1592
1593	bad_page:
1594	pte_unmap_unlock(ptep, ptl);
1595	return ERR_PTR(-EFAULT);
1596
1597	no_page:
1598	pte_unmap_unlock(ptep, ptl);
1599	if (!pte_none(pte))
1600	return page;
1601
1602	no_page_table:
1603	/*
1604	* When core dumping an enormous anonymous area that nobody
1605	* has touched so far, we don't want to allocate unnecessary pages or
1606	* page tables. Return error instead of NULL to skip handle_mm_fault,
1607	* then get_dump_page() will return NULL to leave a hole in the dump.
1608	* But we can only make this optimization where a hole would surely
1609	* be zero-filled if handle_mm_fault() actually did handle it.
1610	*/
1611	if ((flags & FOLL_DUMP) &&
1612	(!vma->vm_ops \|\| !vma->vm_ops->fault))
1613	return ERR_PTR(-EFAULT);
1614	return page;
1615	}
1616
1617	static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1618	{
1619	return stack_guard_page_start(vma, addr) \|\|
1620	stack_guard_page_end(vma, addr+PAGE_SIZE);
1621	}
1622
1623	/**
1624	* __get_user_pages() - pin user pages in memory
1625	* @tsk: task_struct of target task
1626	* @mm: mm_struct of target mm
1627	* @start: starting user address
1628	* @nr_pages: number of pages from start to pin
1629	* @gup_flags: flags modifying pin behaviour
1630	* @pages: array that receives pointers to the pages pinned.
1631	* Should be at least nr_pages long. Or NULL, if caller
1632	* only intends to ensure the pages are faulted in.
1633	* @vmas: array of pointers to vmas corresponding to each page.
1634	* Or NULL if the caller does not require them.
1635	* @nonblocking: whether waiting for disk IO or mmap_sem contention
1636	*
1637	* Returns number of pages pinned. This may be fewer than the number
1638	* requested. If nr_pages is 0 or negative, returns 0. If no pages
1639	* were pinned, returns -errno. Each page returned must be released
1640	* with a put_page() call when it is finished with. vmas will only
1641	* remain valid while mmap_sem is held.
1642	*
1643	* Must be called with mmap_sem held for read or write.
1644	*
1645	* __get_user_pages walks a process's page tables and takes a reference to
1646	* each struct page that each user address corresponds to at a given
1647	* instant. That is, it takes the page that would be accessed if a user
1648	* thread accesses the given user virtual address at that instant.
1649	*
1650	* This does not guarantee that the page exists in the user mappings when
1651	* __get_user_pages returns, and there may even be a completely different
1652	* page there in some cases (eg. if mmapped pagecache has been invalidated
1653	* and subsequently re faulted). However it does guarantee that the page
1654	* won't be freed completely. And mostly callers simply care that the page
1655	* contains data that was valid at some point in time. Typically, an IO
1656	* or similar operation cannot guarantee anything stronger anyway because
1657	* locks can't be held over the syscall boundary.
1658	*
1659	* If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1660	* the page is written to, set_page_dirty (or set_page_dirty_lock, as
1661	* appropriate) must be called after the page is finished with, and
1662	* before put_page is called.
1663	*
1664	* If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1665	* or mmap_sem contention, and if waiting is needed to pin all pages,
1666	* *@nonblocking will be set to 0.
1667	*
1668	* In most cases, get_user_pages or get_user_pages_fast should be used
1669	* instead of __get_user_pages. __get_user_pages should be used only if
1670	* you need some special @gup_flags.
1671	*/
1672	int __get_user_pages(struct task_struct tsk, struct mm_struct mm,
1673	unsigned long start, int nr_pages, unsigned int gup_flags,
1674	struct page pages, struct vm_area_struct vmas,
1675	int *nonblocking)
1676	{
1677	int i;
1678	unsigned long vm_flags;
1679
1680	if (nr_pages <= 0)
1681	return 0;
1682
1683	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1684
1685	/*
1686	* Require read or write permissions.
1687	* If FOLL_FORCE is set, we only require the "MAY" flags.
1688	*/
1689	vm_flags = (gup_flags & FOLL_WRITE) ?
1690	(VM_WRITE \| VM_MAYWRITE) : (VM_READ \| VM_MAYREAD);
1691	vm_flags &= (gup_flags & FOLL_FORCE) ?
1692	(VM_MAYREAD \| VM_MAYWRITE) : (VM_READ \| VM_WRITE);
1693	i = 0;
1694
1695	do {
1696	struct vm_area_struct *vma;
1697
1698	vma = find_extend_vma(mm, start);
1699	if (!vma && in_gate_area(mm, start)) {
1700	unsigned long pg = start & PAGE_MASK;
1701	pgd_t *pgd;
1702	pud_t *pud;
1703	pmd_t *pmd;
1704	pte_t *pte;
1705
1706	/* user gate pages are read-only */
1707	if (gup_flags & FOLL_WRITE)
1708	return i ? : -EFAULT;
1709	if (pg > TASK_SIZE)
1710	pgd = pgd_offset_k(pg);
1711	else
1712	pgd = pgd_offset_gate(mm, pg);
1713	BUG_ON(pgd_none(*pgd));
1714	pud = pud_offset(pgd, pg);
1715	BUG_ON(pud_none(*pud));
1716	pmd = pmd_offset(pud, pg);
1717	if (pmd_none(*pmd))
1718	return i ? : -EFAULT;
1719	VM_BUG_ON(pmd_trans_huge(*pmd));
1720	pte = pte_offset_map(pmd, pg);
1721	if (pte_none(*pte)) {
1722	pte_unmap(pte);
1723	return i ? : -EFAULT;
1724	}
1725	vma = get_gate_vma(mm);
1726	if (pages) {
1727	struct page *page;
1728
1729	page = vm_normal_page(vma, start, *pte);
1730	if (!page) {
1731	if (!(gup_flags & FOLL_DUMP) &&
1732	is_zero_pfn(pte_pfn(*pte)))
1733	page = pte_page(*pte);
1734	else {
1735	pte_unmap(pte);
1736	return i ? : -EFAULT;
1737	}
1738	}
1739	pages[i] = page;
1740	get_page(page);
1741	}
1742	pte_unmap(pte);
1743	goto next_page;
1744	}
1745
1746	if (!vma \|\|
1747	(vma->vm_flags & (VM_IO \| VM_PFNMAP)) \|\|
1748	!(vm_flags & vma->vm_flags))
1749	return i ? : -EFAULT;
1750
1751	if (is_vm_hugetlb_page(vma)) {
1752	i = follow_hugetlb_page(mm, vma, pages, vmas,
1753	&start, &nr_pages, i, gup_flags);
1754	continue;
1755	}
1756
1757	do {
1758	struct page *page;
1759	unsigned int foll_flags = gup_flags;
1760
1761	/*
1762	* If we have a pending SIGKILL, don't keep faulting
1763	* pages and potentially allocating memory.
1764	*/
1765	if (unlikely(fatal_signal_pending(current)))
1766	return i ? i : -ERESTARTSYS;
1767
1768	cond_resched();
1769	while (!(page = follow_page(vma, start, foll_flags))) {
1770	int ret;
1771	unsigned int fault_flags = 0;
1772
1773	/* For mlock, just skip the stack guard page. */
1774	if (foll_flags & FOLL_MLOCK) {
1775	if (stack_guard_page(vma, start))
1776	goto next_page;
1777	}
1778	if (foll_flags & FOLL_WRITE)
1779	fault_flags \|= FAULT_FLAG_WRITE;
1780	if (nonblocking)
1781	fault_flags \|= FAULT_FLAG_ALLOW_RETRY;
1782	if (foll_flags & FOLL_NOWAIT)
1783	fault_flags \|= (FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_RETRY_NOWAIT);
1784
1785	ret = handle_mm_fault(mm, vma, start,
1786	fault_flags);
1787
1788	if (ret & VM_FAULT_ERROR) {
1789	if (ret & VM_FAULT_OOM)
1790	return i ? i : -ENOMEM;
1791	if (ret & (VM_FAULT_HWPOISON \|
1792	VM_FAULT_HWPOISON_LARGE)) {
1793	if (i)
1794	return i;
1795	else if (gup_flags & FOLL_HWPOISON)
1796	return -EHWPOISON;
1797	else
1798	return -EFAULT;
1799	}
1800	if (ret & VM_FAULT_SIGBUS)
1801	return i ? i : -EFAULT;
1802	BUG();
1803	}
1804
1805	if (tsk) {
1806	if (ret & VM_FAULT_MAJOR)
1807	tsk->maj_flt++;
1808	else
1809	tsk->min_flt++;
1810	}
1811
1812	if (ret & VM_FAULT_RETRY) {
1813	if (nonblocking)
1814	*nonblocking = 0;
1815	return i;
1816	}
1817
1818	/*
1819	* The VM_FAULT_WRITE bit tells us that
1820	* do_wp_page has broken COW when necessary,
1821	* even if maybe_mkwrite decided not to set
1822	* pte_write. We can thus safely do subsequent
1823	* page lookups as if they were reads. But only
1824	* do so when looping for pte_write is futile:
1825	* in some cases userspace may also be wanting
1826	* to write to the gotten user page, which a
1827	* read fault here might prevent (a readonly
1828	* page might get reCOWed by userspace write).
1829	*/
1830	if ((ret & VM_FAULT_WRITE) &&
1831	!(vma->vm_flags & VM_WRITE))
1832	foll_flags &= ~FOLL_WRITE;
1833
1834	cond_resched();
1835	}
1836	if (IS_ERR(page))
1837	return i ? i : PTR_ERR(page);
1838	if (pages) {
1839	pages[i] = page;
1840
1841	flush_anon_page(vma, page, start);
1842	flush_dcache_page(page);
1843	}
1844	next_page:
1845	if (vmas)
1846	vmas[i] = vma;
1847	i++;
1848	start += PAGE_SIZE;
1849	nr_pages--;
1850	} while (nr_pages && start < vma->vm_end);
1851	} while (nr_pages);
1852	return i;
1853	}
1854	EXPORT_SYMBOL(__get_user_pages);
1855
1856	/*
1857	* fixup_user_fault() - manually resolve a user page fault
1858	* @tsk: the task_struct to use for page fault accounting, or
1859	* NULL if faults are not to be recorded.
1860	* @mm: mm_struct of target mm
1861	* @address: user address
1862	* @fault_flags:flags to pass down to handle_mm_fault()
1863	*
1864	* This is meant to be called in the specific scenario where for locking reasons
1865	* we try to access user memory in atomic context (within a pagefault_disable()
1866	* section), this returns -EFAULT, and we want to resolve the user fault before
1867	* trying again.
1868	*
1869	* Typically this is meant to be used by the futex code.
1870	*
1871	* The main difference with get_user_pages() is that this function will
1872	* unconditionally call handle_mm_fault() which will in turn perform all the
1873	* necessary SW fixup of the dirty and young bits in the PTE, while
1874	* handle_mm_fault() only guarantees to update these in the struct page.
1875	*
1876	* This is important for some architectures where those bits also gate the
1877	* access permission to the page because they are maintained in software. On
1878	* such architectures, gup() will not be enough to make a subsequent access
1879	* succeed.
1880	*
1881	* This should be called with the mm_sem held for read.
1882	*/
1883	int fixup_user_fault(struct task_struct tsk, struct mm_struct mm,
1884	unsigned long address, unsigned int fault_flags)
1885	{
1886	struct vm_area_struct *vma;
1887	int ret;
1888
1889	vma = find_extend_vma(mm, address);
1890	if (!vma \|\| address < vma->vm_start)
1891	return -EFAULT;
1892
1893	ret = handle_mm_fault(mm, vma, address, fault_flags);
1894	if (ret & VM_FAULT_ERROR) {
1895	if (ret & VM_FAULT_OOM)
1896	return -ENOMEM;
1897	if (ret & (VM_FAULT_HWPOISON \| VM_FAULT_HWPOISON_LARGE))
1898	return -EHWPOISON;
1899	if (ret & VM_FAULT_SIGBUS)
1900	return -EFAULT;
1901	BUG();
1902	}
1903	if (tsk) {
1904	if (ret & VM_FAULT_MAJOR)
1905	tsk->maj_flt++;
1906	else
1907	tsk->min_flt++;
1908	}
1909	return 0;
1910	}
1911
1912	/*
1913	* get_user_pages() - pin user pages in memory
1914	* @tsk: the task_struct to use for page fault accounting, or
1915	* NULL if faults are not to be recorded.
1916	* @mm: mm_struct of target mm
1917	* @start: starting user address
1918	* @nr_pages: number of pages from start to pin
1919	* @write: whether pages will be written to by the caller
1920	* @force: whether to force write access even if user mapping is
1921	* readonly. This will result in the page being COWed even
1922	* in MAP_SHARED mappings. You do not want this.
1923	* @pages: array that receives pointers to the pages pinned.
1924	* Should be at least nr_pages long. Or NULL, if caller
1925	* only intends to ensure the pages are faulted in.
1926	* @vmas: array of pointers to vmas corresponding to each page.
1927	* Or NULL if the caller does not require them.
1928	*
1929	* Returns number of pages pinned. This may be fewer than the number
1930	* requested. If nr_pages is 0 or negative, returns 0. If no pages
1931	* were pinned, returns -errno. Each page returned must be released
1932	* with a put_page() call when it is finished with. vmas will only
1933	* remain valid while mmap_sem is held.
1934	*
1935	* Must be called with mmap_sem held for read or write.
1936	*
1937	* get_user_pages walks a process's page tables and takes a reference to
1938	* each struct page that each user address corresponds to at a given
1939	* instant. That is, it takes the page that would be accessed if a user
1940	* thread accesses the given user virtual address at that instant.
1941	*
1942	* This does not guarantee that the page exists in the user mappings when
1943	* get_user_pages returns, and there may even be a completely different
1944	* page there in some cases (eg. if mmapped pagecache has been invalidated
1945	* and subsequently re faulted). However it does guarantee that the page
1946	* won't be freed completely. And mostly callers simply care that the page
1947	* contains data that was valid at some point in time. Typically, an IO
1948	* or similar operation cannot guarantee anything stronger anyway because
1949	* locks can't be held over the syscall boundary.
1950	*
1951	* If write=0, the page must not be written to. If the page is written to,
1952	* set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1953	* after the page is finished with, and before put_page is called.
1954	*
1955	* get_user_pages is typically used for fewer-copy IO operations, to get a
1956	* handle on the memory by some means other than accesses via the user virtual
1957	* addresses. The pages may be submitted for DMA to devices or accessed via
1958	* their kernel linear mapping (via the kmap APIs). Care should be taken to
1959	* use the correct cache flushing APIs.
1960	*
1961	* See also get_user_pages_fast, for performance critical applications.
1962	*/
1963	int get_user_pages(struct task_struct tsk, struct mm_struct mm,
1964	unsigned long start, int nr_pages, int write, int force,
1965	struct page pages, struct vm_area_struct vmas)
1966	{
1967	int flags = FOLL_TOUCH;
1968
1969	if (pages)
1970	flags \|= FOLL_GET;
1971	if (write)
1972	flags \|= FOLL_WRITE;
1973	if (force)
1974	flags \|= FOLL_FORCE;
1975
1976	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1977	NULL);
1978	}
1979	EXPORT_SYMBOL(get_user_pages);
1980
1981	/**
1982	* get_dump_page() - pin user page in memory while writing it to core dump
1983	* @addr: user address
1984	*
1985	* Returns struct page pointer of user page pinned for dump,
1986	* to be freed afterwards by page_cache_release() or put_page().
1987	*
1988	* Returns NULL on any kind of failure - a hole must then be inserted into
1989	* the corefile, to preserve alignment with its headers; and also returns
1990	* NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1991	* allowing a hole to be left in the corefile to save diskspace.
1992	*
1993	* Called without mmap_sem, but after all other threads have been killed.
1994	*/
1995	#ifdef CONFIG_ELF_CORE
1996	struct page *get_dump_page(unsigned long addr)
1997	{
1998	struct vm_area_struct *vma;
1999	struct page *page;
2000
2001	if (__get_user_pages(current, current->mm, addr, 1,
2002	FOLL_FORCE \| FOLL_DUMP \| FOLL_GET, &page, &vma,
2003	NULL) < 1)
2004	return NULL;
2005	flush_cache_page(vma, addr, page_to_pfn(page));
2006	return page;
2007	}
2008	#endif /* CONFIG_ELF_CORE */
2009
2010	pte_t __get_locked_pte(struct mm_struct mm, unsigned long addr,
2011	spinlock_t **ptl)
2012	{
2013	pgd_t * pgd = pgd_offset(mm, addr);
2014	pud_t * pud = pud_alloc(mm, pgd, addr);
2015	if (pud) {
2016	pmd_t * pmd = pmd_alloc(mm, pud, addr);
2017	if (pmd) {
2018	VM_BUG_ON(pmd_trans_huge(*pmd));
2019	return pte_alloc_map_lock(mm, pmd, addr, ptl);
2020	}
2021	}
2022	return NULL;
2023	}
2024
2025	/*
2026	* This is the old fallback for page remapping.
2027	*
2028	* For historical reasons, it only allows reserved pages. Only
2029	* old drivers should use this, and they needed to mark their
2030	* pages reserved for the old functions anyway.
2031	*/
2032	static int insert_page(struct vm_area_struct *vma, unsigned long addr,
2033	struct page *page, pgprot_t prot)
2034	{
2035	struct mm_struct *mm = vma->vm_mm;
2036	int retval;
2037	pte_t *pte;
2038	spinlock_t *ptl;
2039
2040	retval = -EINVAL;
2041	if (PageAnon(page))
2042	goto out;
2043	retval = -ENOMEM;
2044	flush_dcache_page(page);
2045	pte = get_locked_pte(mm, addr, &ptl);
2046	if (!pte)
2047	goto out;
2048	retval = -EBUSY;
2049	if (!pte_none(*pte))
2050	goto out_unlock;
2051
2052	/* Ok, finally just insert the thing.. */
2053	get_page(page);
2054	inc_mm_counter_fast(mm, MM_FILEPAGES);
2055	page_add_file_rmap(page);
2056	set_pte_at(mm, addr, pte, mk_pte(page, prot));
2057
2058	retval = 0;
2059	pte_unmap_unlock(pte, ptl);
2060	return retval;
2061	out_unlock:
2062	pte_unmap_unlock(pte, ptl);
2063	out:
2064	return retval;
2065	}
2066
2067	/**
2068	* vm_insert_page - insert single page into user vma
2069	* @vma: user vma to map to
2070	* @addr: target user address of this page
2071	* @page: source kernel page
2072	*
2073	* This allows drivers to insert individual pages they've allocated
2074	* into a user vma.
2075	*
2076	* The page has to be a nice clean _individual_ kernel allocation.
2077	* If you allocate a compound page, you need to have marked it as
2078	* such (__GFP_COMP), or manually just split the page up yourself
2079	* (see split_page()).
2080	*
2081	* NOTE! Traditionally this was done with "remap_pfn_range()" which
2082	* took an arbitrary page protection parameter. This doesn't allow
2083	* that. Your vma protection will have to be set up correctly, which
2084	* means that if you want a shared writable mapping, you'd better
2085	* ask for a shared writable mapping!
2086	*
2087	* The page does not need to be reserved.
2088	*/
2089	int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2090	struct page *page)
2091	{
2092	if (addr < vma->vm_start \|\| addr >= vma->vm_end)
2093	return -EFAULT;
2094	if (!page_count(page))
2095	return -EINVAL;
2096	vma->vm_flags \|= VM_INSERTPAGE;
2097	return insert_page(vma, addr, page, vma->vm_page_prot);
2098	}
2099	EXPORT_SYMBOL(vm_insert_page);
2100
2101	static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2102	unsigned long pfn, pgprot_t prot)
2103	{
2104	struct mm_struct *mm = vma->vm_mm;
2105	int retval;
2106	pte_t *pte, entry;
2107	spinlock_t *ptl;
2108
2109	retval = -ENOMEM;
2110	pte = get_locked_pte(mm, addr, &ptl);
2111	if (!pte)
2112	goto out;
2113	retval = -EBUSY;
2114	if (!pte_none(*pte))
2115	goto out_unlock;
2116
2117	/* Ok, finally just insert the thing.. */
2118	entry = pte_mkspecial(pfn_pte(pfn, prot));
2119	set_pte_at(mm, addr, pte, entry);
2120	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2121
2122	retval = 0;
2123	out_unlock:
2124	pte_unmap_unlock(pte, ptl);
2125	out:
2126	return retval;
2127	}
2128
2129	/**
2130	* vm_insert_pfn - insert single pfn into user vma
2131	* @vma: user vma to map to
2132	* @addr: target user address of this page
2133	* @pfn: source kernel pfn
2134	*
2135	* Similar to vm_inert_page, this allows drivers to insert individual pages
2136	* they've allocated into a user vma. Same comments apply.
2137	*
2138	* This function should only be called from a vm_ops->fault handler, and
2139	* in that case the handler should return NULL.
2140	*
2141	* vma cannot be a COW mapping.
2142	*
2143	* As this is called only for pages that do not currently exist, we
2144	* do not need to flush old virtual caches or the TLB.
2145	*/
2146	int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2147	unsigned long pfn)
2148	{
2149	int ret;
2150	pgprot_t pgprot = vma->vm_page_prot;
2151	/*
2152	* Technically, architectures with pte_special can avoid all these
2153	* restrictions (same for remap_pfn_range). However we would like
2154	* consistency in testing and feature parity among all, so we should
2155	* try to keep these invariants in place for everybody.
2156	*/
2157	BUG_ON(!(vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP)));
2158	BUG_ON((vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP)) ==
2159	(VM_PFNMAP\|VM_MIXEDMAP));
2160	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2161	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2162
2163	if (addr < vma->vm_start \|\| addr >= vma->vm_end)
2164	return -EFAULT;
2165	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
2166	return -EINVAL;
2167
2168	ret = insert_pfn(vma, addr, pfn, pgprot);
2169
2170	if (ret)
2171	untrack_pfn_vma(vma, pfn, PAGE_SIZE);
2172
2173	return ret;
2174	}
2175	EXPORT_SYMBOL(vm_insert_pfn);
2176
2177	int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2178	unsigned long pfn)
2179	{
2180	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2181
2182	if (addr < vma->vm_start \|\| addr >= vma->vm_end)
2183	return -EFAULT;
2184
2185	/*
2186	* If we don't have pte special, then we have to use the pfn_valid()
2187	* based VM_MIXEDMAP scheme (see vm_normal_page), and thus we must
2188	* refcount the page if pfn_valid is true (hence insert_page rather
2189	* than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2190	* without pte special, it would there be refcounted as a normal page.
2191	*/
2192	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2193	struct page *page;
2194
2195	page = pfn_to_page(pfn);
2196	return insert_page(vma, addr, page, vma->vm_page_prot);
2197	}
2198	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2199	}
2200	EXPORT_SYMBOL(vm_insert_mixed);
2201
2202	/*
2203	* maps a range of physical memory into the requested pages. the old
2204	* mappings are removed. any references to nonexistent pages results
2205	* in null mappings (currently treated as "copy-on-access")
2206	*/
2207	static int remap_pte_range(struct mm_struct mm, pmd_t pmd,
2208	unsigned long addr, unsigned long end,
2209	unsigned long pfn, pgprot_t prot)
2210	{
2211	pte_t *pte;
2212	spinlock_t *ptl;
2213
2214	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2215	if (!pte)
2216	return -ENOMEM;
2217	arch_enter_lazy_mmu_mode();
2218	do {
2219	BUG_ON(!pte_none(*pte));
2220	set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2221	pfn++;
2222	} while (pte++, addr += PAGE_SIZE, addr != end);
2223	arch_leave_lazy_mmu_mode();
2224	pte_unmap_unlock(pte - 1, ptl);
2225	return 0;
2226	}
2227
2228	static inline int remap_pmd_range(struct mm_struct mm, pud_t pud,
2229	unsigned long addr, unsigned long end,
2230	unsigned long pfn, pgprot_t prot)
2231	{
2232	pmd_t *pmd;
2233	unsigned long next;
2234
2235	pfn -= addr >> PAGE_SHIFT;
2236	pmd = pmd_alloc(mm, pud, addr);
2237	if (!pmd)
2238	return -ENOMEM;
2239	VM_BUG_ON(pmd_trans_huge(*pmd));
2240	do {
2241	next = pmd_addr_end(addr, end);
2242	if (remap_pte_range(mm, pmd, addr, next,
2243	pfn + (addr >> PAGE_SHIFT), prot))
2244	return -ENOMEM;
2245	} while (pmd++, addr = next, addr != end);
2246	return 0;
2247	}
2248
2249	static inline int remap_pud_range(struct mm_struct mm, pgd_t pgd,
2250	unsigned long addr, unsigned long end,
2251	unsigned long pfn, pgprot_t prot)
2252	{
2253	pud_t *pud;
2254	unsigned long next;
2255
2256	pfn -= addr >> PAGE_SHIFT;
2257	pud = pud_alloc(mm, pgd, addr);
2258	if (!pud)
2259	return -ENOMEM;
2260	do {
2261	next = pud_addr_end(addr, end);
2262	if (remap_pmd_range(mm, pud, addr, next,
2263	pfn + (addr >> PAGE_SHIFT), prot))
2264	return -ENOMEM;
2265	} while (pud++, addr = next, addr != end);
2266	return 0;
2267	}
2268
2269	/**
2270	* remap_pfn_range - remap kernel memory to userspace
2271	* @vma: user vma to map to
2272	* @addr: target user address to start at
2273	* @pfn: physical address of kernel memory
2274	* @size: size of map area
2275	* @prot: page protection flags for this mapping
2276	*
2277	* Note: this is only safe if the mm semaphore is held when called.
2278	*/
2279	int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2280	unsigned long pfn, unsigned long size, pgprot_t prot)
2281	{
2282	pgd_t *pgd;
2283	unsigned long next;
2284	unsigned long end = addr + PAGE_ALIGN(size);
2285	struct mm_struct *mm = vma->vm_mm;
2286	int err;
2287
2288	/*
2289	* Physically remapped pages are special. Tell the
2290	* rest of the world about it:
2291	* VM_IO tells people not to look at these pages
2292	* (accesses can have side effects).
2293	* VM_RESERVED is specified all over the place, because
2294	* in 2.4 it kept swapout's vma scan off this vma; but
2295	* in 2.6 the LRU scan won't even find its pages, so this
2296	* flag means no more than count its pages in reserved_vm,
2297	* and omit it from core dump, even when VM_IO turned off.
2298	* VM_PFNMAP tells the core MM that the base pages are just
2299	* raw PFN mappings, and do not have a "struct page" associated
2300	* with them.
2301	*
2302	* There's a horrible special case to handle copy-on-write
2303	* behaviour that some programs depend on. We mark the "original"
2304	* un-COW'ed pages by matching them up with "vma->vm_pgoff".
2305	*/
2306	if (addr == vma->vm_start && end == vma->vm_end) {
2307	vma->vm_pgoff = pfn;
2308	vma->vm_flags \|= VM_PFN_AT_MMAP;
2309	} else if (is_cow_mapping(vma->vm_flags))
2310	return -EINVAL;
2311
2312	vma->vm_flags \|= VM_IO \| VM_RESERVED \| VM_PFNMAP;
2313
2314	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2315	if (err) {
2316	/*
2317	* To indicate that track_pfn related cleanup is not
2318	* needed from higher level routine calling unmap_vmas
2319	*/
2320	vma->vm_flags &= ~(VM_IO \| VM_RESERVED \| VM_PFNMAP);
2321	vma->vm_flags &= ~VM_PFN_AT_MMAP;
2322	return -EINVAL;
2323	}
2324
2325	BUG_ON(addr >= end);
2326	pfn -= addr >> PAGE_SHIFT;
2327	pgd = pgd_offset(mm, addr);
2328	flush_cache_range(vma, addr, end);
2329	do {
2330	next = pgd_addr_end(addr, end);
2331	err = remap_pud_range(mm, pgd, addr, next,
2332	pfn + (addr >> PAGE_SHIFT), prot);
2333	if (err)
2334	break;
2335	} while (pgd++, addr = next, addr != end);
2336
2337	if (err)
2338	untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2339
2340	return err;
2341	}
2342	EXPORT_SYMBOL(remap_pfn_range);
2343
2344	static int apply_to_pte_range(struct mm_struct mm, pmd_t pmd,
2345	unsigned long addr, unsigned long end,
2346	pte_fn_t fn, void *data)
2347	{
2348	pte_t *pte;
2349	int err;
2350	pgtable_t token;
2351	spinlock_t *uninitialized_var(ptl);
2352
2353	pte = (mm == &init_mm) ?
2354	pte_alloc_kernel(pmd, addr) :
2355	pte_alloc_map_lock(mm, pmd, addr, &ptl);
2356	if (!pte)
2357	return -ENOMEM;
2358
2359	BUG_ON(pmd_huge(*pmd));
2360
2361	arch_enter_lazy_mmu_mode();
2362
2363	token = pmd_pgtable(*pmd);
2364
2365	do {
2366	err = fn(pte++, token, addr, data);
2367	if (err)
2368	break;
2369	} while (addr += PAGE_SIZE, addr != end);
2370
2371	arch_leave_lazy_mmu_mode();
2372
2373	if (mm != &init_mm)
2374	pte_unmap_unlock(pte-1, ptl);
2375	return err;
2376	}
2377
2378	static int apply_to_pmd_range(struct mm_struct mm, pud_t pud,
2379	unsigned long addr, unsigned long end,
2380	pte_fn_t fn, void *data)
2381	{
2382	pmd_t *pmd;
2383	unsigned long next;
2384	int err;
2385
2386	BUG_ON(pud_huge(*pud));
2387
2388	pmd = pmd_alloc(mm, pud, addr);
2389	if (!pmd)
2390	return -ENOMEM;
2391	do {
2392	next = pmd_addr_end(addr, end);
2393	err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2394	if (err)
2395	break;
2396	} while (pmd++, addr = next, addr != end);
2397	return err;
2398	}
2399
2400	static int apply_to_pud_range(struct mm_struct mm, pgd_t pgd,
2401	unsigned long addr, unsigned long end,
2402	pte_fn_t fn, void *data)
2403	{
2404	pud_t *pud;
2405	unsigned long next;
2406	int err;
2407
2408	pud = pud_alloc(mm, pgd, addr);
2409	if (!pud)
2410	return -ENOMEM;
2411	do {
2412	next = pud_addr_end(addr, end);
2413	err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2414	if (err)
2415	break;
2416	} while (pud++, addr = next, addr != end);
2417	return err;
2418	}
2419
2420	/*
2421	* Scan a region of virtual memory, filling in page tables as necessary
2422	* and calling a provided function on each leaf page table.
2423	*/
2424	int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2425	unsigned long size, pte_fn_t fn, void *data)
2426	{
2427	pgd_t *pgd;
2428	unsigned long next;
2429	unsigned long end = addr + size;
2430	int err;
2431
2432	BUG_ON(addr >= end);
2433	pgd = pgd_offset(mm, addr);
2434	do {
2435	next = pgd_addr_end(addr, end);
2436	err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2437	if (err)
2438	break;
2439	} while (pgd++, addr = next, addr != end);
2440
2441	return err;
2442	}
2443	EXPORT_SYMBOL_GPL(apply_to_page_range);
2444
2445	/*
2446	* handle_pte_fault chooses page fault handler according to an entry
2447	* which was read non-atomically. Before making any commitment, on
2448	* those architectures or configurations (e.g. i386 with PAE) which
2449	* might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2450	* must check under lock before unmapping the pte and proceeding
2451	* (but do_wp_page is only called after already making such a check;
2452	* and do_anonymous_page can safely check later on).
2453	*/
2454	static inline int pte_unmap_same(struct mm_struct mm, pmd_t pmd,
2455	pte_t *page_table, pte_t orig_pte)
2456	{
2457	int same = 1;
2458	#if defined(CONFIG_SMP) \|\| defined(CONFIG_PREEMPT)
2459	if (sizeof(pte_t) > sizeof(unsigned long)) {
2460	spinlock_t *ptl = pte_lockptr(mm, pmd);
2461	spin_lock(ptl);
2462	same = pte_same(*page_table, orig_pte);
2463	spin_unlock(ptl);
2464	}
2465	#endif
2466	pte_unmap(page_table);
2467	return same;
2468	}
2469
2470	static inline void cow_user_page(struct page dst, struct page src, unsigned long va, struct vm_area_struct *vma)
2471	{
2472	/*
2473	* If the source page was a PFN mapping, we don't have
2474	* a "struct page" for it. We do a best-effort copy by
2475	* just copying from the original user address. If that
2476	* fails, we just zero-fill it. Live with it.
2477	*/
2478	if (unlikely(!src)) {
2479	void *kaddr = kmap_atomic(dst);
2480	void __user uaddr = (void __user )(va & PAGE_MASK);
2481
2482	/*
2483	* This really shouldn't fail, because the page is there
2484	* in the page tables. But it might just be unreadable,
2485	* in which case we just give up and fill the result with
2486	* zeroes.
2487	*/
2488	if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2489	clear_page(kaddr);
2490	kunmap_atomic(kaddr);
2491	flush_dcache_page(dst);
2492	} else
2493	copy_user_highpage(dst, src, va, vma);
2494	}
2495
2496	/*
2497	* This routine handles present pages, when users try to write
2498	* to a shared page. It is done by copying the page to a new address
2499	* and decrementing the shared-page counter for the old page.
2500	*
2501	* Note that this routine assumes that the protection checks have been
2502	* done by the caller (the low-level page fault routine in most cases).
2503	* Thus we can safely just mark it writable once we've done any necessary
2504	* COW.
2505	*
2506	* We also mark the page dirty at this point even though the page will
2507	* change only once the write actually happens. This avoids a few races,
2508	* and potentially makes it more efficient.
2509	*
2510	* We enter with non-exclusive mmap_sem (to exclude vma changes,
2511	* but allow concurrent faults), with pte both mapped and locked.
2512	* We return with mmap_sem still held, but pte unmapped and unlocked.
2513	*/
2514	static int do_wp_page(struct mm_struct mm, struct vm_area_struct vma,
2515	unsigned long address, pte_t page_table, pmd_t pmd,
2516	spinlock_t *ptl, pte_t orig_pte)
2517	__releases(ptl)
2518	{
2519	struct page old_page, new_page;
2520	pte_t entry;
2521	int ret = 0;
2522	int page_mkwrite = 0;
2523	struct page *dirty_page = NULL;
2524
2525	old_page = vm_normal_page(vma, address, orig_pte);
2526	if (!old_page) {
2527	/*
2528	* VM_MIXEDMAP !pfn_valid() case
2529	*
2530	* We should not cow pages in a shared writeable mapping.
2531	* Just mark the pages writable as we can't do any dirty
2532	* accounting on raw pfn maps.
2533	*/
2534	if ((vma->vm_flags & (VM_WRITE\|VM_SHARED)) ==
2535	(VM_WRITE\|VM_SHARED))
2536	goto reuse;
2537	goto gotten;
2538	}
2539
2540	/*
2541	* Take out anonymous pages first, anonymous shared vmas are
2542	* not dirty accountable.
2543	*/
2544	if (PageAnon(old_page) && !PageKsm(old_page)) {
2545	if (!trylock_page(old_page)) {
2546	page_cache_get(old_page);
2547	pte_unmap_unlock(page_table, ptl);
2548	lock_page(old_page);
2549	page_table = pte_offset_map_lock(mm, pmd, address,
2550	&ptl);
2551	if (!pte_same(*page_table, orig_pte)) {
2552	unlock_page(old_page);
2553	goto unlock;
2554	}
2555	page_cache_release(old_page);
2556	}
2557	if (reuse_swap_page(old_page)) {
2558	/*
2559	* The page is all ours. Move it to our anon_vma so
2560	* the rmap code will not search our parent or siblings.
2561	* Protected against the rmap code by the page lock.
2562	*/
2563	page_move_anon_rmap(old_page, vma, address);
2564	unlock_page(old_page);
2565	goto reuse;
2566	}
2567	unlock_page(old_page);
2568	} else if (unlikely((vma->vm_flags & (VM_WRITE\|VM_SHARED)) ==
2569	(VM_WRITE\|VM_SHARED))) {
2570	/*
2571	* Only catch write-faults on shared writable pages,
2572	* read-only shared pages can get COWed by
2573	* get_user_pages(.write=1, .force=1).
2574	*/
2575	if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2576	struct vm_fault vmf;
2577	int tmp;
2578
2579	vmf.virtual_address = (void __user *)(address &
2580	PAGE_MASK);
2581	vmf.pgoff = old_page->index;
2582	vmf.flags = FAULT_FLAG_WRITE\|FAULT_FLAG_MKWRITE;
2583	vmf.page = old_page;
2584
2585	/*
2586	* Notify the address space that the page is about to
2587	* become writable so that it can prohibit this or wait
2588	* for the page to get into an appropriate state.
2589	*
2590	* We do this without the lock held, so that it can
2591	* sleep if it needs to.
2592	*/
2593	page_cache_get(old_page);
2594	pte_unmap_unlock(page_table, ptl);
2595
2596	tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2597	if (unlikely(tmp &
2598	(VM_FAULT_ERROR \| VM_FAULT_NOPAGE))) {
2599	ret = tmp;
2600	goto unwritable_page;
2601	}
2602	if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2603	lock_page(old_page);
2604	if (!old_page->mapping) {
2605	ret = 0; /* retry the fault */
2606	unlock_page(old_page);
2607	goto unwritable_page;
2608	}
2609	} else
2610	VM_BUG_ON(!PageLocked(old_page));
2611
2612	/*
2613	* Since we dropped the lock we need to revalidate
2614	* the PTE as someone else may have changed it. If
2615	* they did, we just return, as we can count on the
2616	* MMU to tell us if they didn't also make it writable.
2617	*/
2618	page_table = pte_offset_map_lock(mm, pmd, address,
2619	&ptl);
2620	if (!pte_same(*page_table, orig_pte)) {
2621	unlock_page(old_page);
2622	goto unlock;
2623	}
2624
2625	page_mkwrite = 1;
2626	}
2627	dirty_page = old_page;
2628	get_page(dirty_page);
2629
2630	reuse:
2631	flush_cache_page(vma, address, pte_pfn(orig_pte));
2632	entry = pte_mkyoung(orig_pte);
2633	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2634	if (ptep_set_access_flags(vma, address, page_table, entry,1))
2635	update_mmu_cache(vma, address, page_table);
2636	pte_unmap_unlock(page_table, ptl);
2637	ret \|= VM_FAULT_WRITE;
2638
2639	if (!dirty_page)
2640	return ret;
2641
2642	/*
2643	* Yes, Virginia, this is actually required to prevent a race
2644	* with clear_page_dirty_for_io() from clearing the page dirty
2645	* bit after it clear all dirty ptes, but before a racing
2646	* do_wp_page installs a dirty pte.
2647	*
2648	* __do_fault is protected similarly.
2649	*/
2650	if (!page_mkwrite) {
2651	wait_on_page_locked(dirty_page);
2652	set_page_dirty_balance(dirty_page, page_mkwrite);
2653	/* file_update_time outside page_lock */
2654	if (vma->vm_file)
2655	file_update_time(vma->vm_file);
2656	}
2657	put_page(dirty_page);
2658	if (page_mkwrite) {
2659	struct address_space *mapping = dirty_page->mapping;
2660
2661	set_page_dirty(dirty_page);
2662	unlock_page(dirty_page);
2663	page_cache_release(dirty_page);
2664	if (mapping) {
2665	/*
2666	* Some device drivers do not set page.mapping
2667	* but still dirty their pages
2668	*/
2669	balance_dirty_pages_ratelimited(mapping);
2670	}
2671	}
2672
2673	return ret;
2674	}
2675
2676	/*
2677	* Ok, we need to copy. Oh, well..
2678	*/
2679	page_cache_get(old_page);
2680	gotten:
2681	pte_unmap_unlock(page_table, ptl);
2682
2683	if (unlikely(anon_vma_prepare(vma)))
2684	goto oom;
2685
2686	if (is_zero_pfn(pte_pfn(orig_pte))) {
2687	new_page = alloc_zeroed_user_highpage_movable(vma, address);
2688	if (!new_page)
2689	goto oom;
2690	} else {
2691	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2692	if (!new_page)
2693	goto oom;
2694	cow_user_page(new_page, old_page, address, vma);
2695	}
2696	__SetPageUptodate(new_page);
2697
2698	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2699	goto oom_free_new;
2700
2701	/*
2702	* Re-check the pte - we dropped the lock
2703	*/
2704	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2705	if (likely(pte_same(*page_table, orig_pte))) {
2706	if (old_page) {
2707	if (!PageAnon(old_page)) {
2708	dec_mm_counter_fast(mm, MM_FILEPAGES);
2709	inc_mm_counter_fast(mm, MM_ANONPAGES);
2710	}
2711	} else
2712	inc_mm_counter_fast(mm, MM_ANONPAGES);
2713	flush_cache_page(vma, address, pte_pfn(orig_pte));
2714	entry = mk_pte(new_page, vma->vm_page_prot);
2715	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2716	/*
2717	* Clear the pte entry and flush it first, before updating the
2718	* pte with the new entry. This will avoid a race condition
2719	* seen in the presence of one thread doing SMC and another
2720	* thread doing COW.
2721	*/
2722	ptep_clear_flush(vma, address, page_table);
2723	page_add_new_anon_rmap(new_page, vma, address);
2724	/*
2725	* We call the notify macro here because, when using secondary
2726	* mmu page tables (such as kvm shadow page tables), we want the
2727	* new page to be mapped directly into the secondary page table.
2728	*/
2729	set_pte_at_notify(mm, address, page_table, entry);
2730	update_mmu_cache(vma, address, page_table);
2731	if (old_page) {
2732	/*
2733	* Only after switching the pte to the new page may
2734	* we remove the mapcount here. Otherwise another
2735	* process may come and find the rmap count decremented
2736	* before the pte is switched to the new page, and
2737	* "reuse" the old page writing into it while our pte
2738	* here still points into it and can be read by other
2739	* threads.
2740	*
2741	* The critical issue is to order this
2742	* page_remove_rmap with the ptp_clear_flush above.
2743	* Those stores are ordered by (if nothing else,)
2744	* the barrier present in the atomic_add_negative
2745	* in page_remove_rmap.
2746	*
2747	* Then the TLB flush in ptep_clear_flush ensures that
2748	* no process can access the old page before the
2749	* decremented mapcount is visible. And the old page
2750	* cannot be reused until after the decremented
2751	* mapcount is visible. So transitively, TLBs to
2752	* old page will be flushed before it can be reused.
2753	*/
2754	page_remove_rmap(old_page);
2755	}
2756
2757	/* Free the old page.. */
2758	new_page = old_page;
2759	ret \|= VM_FAULT_WRITE;
2760	} else
2761	mem_cgroup_uncharge_page(new_page);
2762
2763	if (new_page)
2764	page_cache_release(new_page);
2765	unlock:
2766	pte_unmap_unlock(page_table, ptl);
2767	if (old_page) {
2768	/*
2769	* Don't let another task, with possibly unlocked vma,
2770	* keep the mlocked page.
2771	*/
2772	if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2773	lock_page(old_page); /* LRU manipulation */
2774	munlock_vma_page(old_page);
2775	unlock_page(old_page);
2776	}
2777	page_cache_release(old_page);
2778	}
2779	return ret;
2780	oom_free_new:
2781	page_cache_release(new_page);
2782	oom:
2783	if (old_page) {
2784	if (page_mkwrite) {
2785	unlock_page(old_page);
2786	page_cache_release(old_page);
2787	}
2788	page_cache_release(old_page);
2789	}
2790	return VM_FAULT_OOM;
2791
2792	unwritable_page:
2793	page_cache_release(old_page);
2794	return ret;
2795	}
2796
2797	static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2798	unsigned long start_addr, unsigned long end_addr,
2799	struct zap_details *details)
2800	{
2801	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2802	}
2803
2804	static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2805	struct zap_details *details)
2806	{
2807	struct vm_area_struct *vma;
2808	struct prio_tree_iter iter;
2809	pgoff_t vba, vea, zba, zea;
2810
2811	vma_prio_tree_foreach(vma, &iter, root,
2812	details->first_index, details->last_index) {
2813
2814	vba = vma->vm_pgoff;
2815	vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2816	/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2817	zba = details->first_index;
2818	if (zba < vba)
2819	zba = vba;
2820	zea = details->last_index;
2821	if (zea > vea)
2822	zea = vea;
2823
2824	unmap_mapping_range_vma(vma,
2825	((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2826	((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2827	details);
2828	}
2829	}
2830
2831	static inline void unmap_mapping_range_list(struct list_head *head,
2832	struct zap_details *details)
2833	{
2834	struct vm_area_struct *vma;
2835
2836	/*
2837	* In nonlinear VMAs there is no correspondence between virtual address
2838	* offset and file offset. So we must perform an exhaustive search
2839	* across all the pages in each nonlinear VMA, not just the pages
2840	* whose virtual address lies outside the file truncation point.
2841	*/
2842	list_for_each_entry(vma, head, shared.vm_set.list) {
2843	details->nonlinear_vma = vma;
2844	unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2845	}
2846	}
2847
2848	/**
2849	* unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2850	* @mapping: the address space containing mmaps to be unmapped.
2851	* @holebegin: byte in first page to unmap, relative to the start of
2852	* the underlying file. This will be rounded down to a PAGE_SIZE
2853	* boundary. Note that this is different from truncate_pagecache(), which
2854	* must keep the partial page. In contrast, we must get rid of
2855	* partial pages.
2856	* @holelen: size of prospective hole in bytes. This will be rounded
2857	* up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2858	* end of the file.
2859	* @even_cows: 1 when truncating a file, unmap even private COWed pages;
2860	* but 0 when invalidating pagecache, don't throw away private data.
2861	*/
2862	void unmap_mapping_range(struct address_space *mapping,
2863	loff_t const holebegin, loff_t const holelen, int even_cows)
2864	{
2865	struct zap_details details;
2866	pgoff_t hba = holebegin >> PAGE_SHIFT;
2867	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2868
2869	/* Check for overflow. */
2870	if (sizeof(holelen) > sizeof(hlen)) {
2871	long long holeend =
2872	(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2873	if (holeend & ~(long long)ULONG_MAX)
2874	hlen = ULONG_MAX - hba + 1;
2875	}
2876
2877	details.check_mapping = even_cows? NULL: mapping;
2878	details.nonlinear_vma = NULL;
2879	details.first_index = hba;
2880	details.last_index = hba + hlen - 1;
2881	if (details.last_index < details.first_index)
2882	details.last_index = ULONG_MAX;
2883
2884
2885	mutex_lock(&mapping->i_mmap_mutex);
2886	if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2887	unmap_mapping_range_tree(&mapping->i_mmap, &details);
2888	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2889	unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2890	mutex_unlock(&mapping->i_mmap_mutex);
2891	}
2892	EXPORT_SYMBOL(unmap_mapping_range);
2893
2894	/*
2895	* We enter with non-exclusive mmap_sem (to exclude vma changes,
2896	* but allow concurrent faults), and pte mapped but not yet locked.
2897	* We return with mmap_sem still held, but pte unmapped and unlocked.
2898	*/
2899	static int do_swap_page(struct mm_struct mm, struct vm_area_struct vma,
2900	unsigned long address, pte_t page_table, pmd_t pmd,
2901	unsigned int flags, pte_t orig_pte)
2902	{
2903	spinlock_t *ptl;
2904	struct page page, swapcache = NULL;
2905	swp_entry_t entry;
2906	pte_t pte;
2907	int locked;
2908	struct mem_cgroup *ptr;
2909	int exclusive = 0;
2910	int ret = 0;
2911
2912	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2913	goto out;
2914
2915	entry = pte_to_swp_entry(orig_pte);
2916	if (unlikely(non_swap_entry(entry))) {
2917	if (is_migration_entry(entry)) {
2918	migration_entry_wait(mm, pmd, address);
2919	} else if (is_hwpoison_entry(entry)) {
2920	ret = VM_FAULT_HWPOISON;
2921	} else {
2922	print_bad_pte(vma, address, orig_pte, NULL);
2923	ret = VM_FAULT_SIGBUS;
2924	}
2925	goto out;
2926	}
2927	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2928	page = lookup_swap_cache(entry);
2929	if (!page) {
2930	page = swapin_readahead(entry,
2931	GFP_HIGHUSER_MOVABLE, vma, address);
2932	if (!page) {
2933	/*
2934	* Back out if somebody else faulted in this pte
2935	* while we released the pte lock.
2936	*/
2937	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2938	if (likely(pte_same(*page_table, orig_pte)))
2939	ret = VM_FAULT_OOM;
2940	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2941	goto unlock;
2942	}
2943
2944	/* Had to read the page from swap area: Major fault */
2945	ret = VM_FAULT_MAJOR;
2946	count_vm_event(PGMAJFAULT);
2947	mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2948	} else if (PageHWPoison(page)) {
2949	/*
2950	* hwpoisoned dirty swapcache pages are kept for killing
2951	* owner processes (which may be unknown at hwpoison time)
2952	*/
2953	ret = VM_FAULT_HWPOISON;
2954	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2955	goto out_release;
2956	}
2957
2958	locked = lock_page_or_retry(page, mm, flags);
2959
2960	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2961	if (!locked) {
2962	ret \|= VM_FAULT_RETRY;
2963	goto out_release;
2964	}
2965
2966	/*
2967	* Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2968	* release the swapcache from under us. The page pin, and pte_same
2969	* test below, are not enough to exclude that. Even if it is still
2970	* swapcache, we need to check that the page's swap has not changed.
2971	*/
2972	if (unlikely(!PageSwapCache(page) \|\| page_private(page) != entry.val))
2973	goto out_page;
2974
2975	if (ksm_might_need_to_copy(page, vma, address)) {
2976	swapcache = page;
2977	page = ksm_does_need_to_copy(page, vma, address);
2978
2979	if (unlikely(!page)) {
2980	ret = VM_FAULT_OOM;
2981	page = swapcache;
2982	swapcache = NULL;
2983	goto out_page;
2984	}
2985	}
2986
2987	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2988	ret = VM_FAULT_OOM;
2989	goto out_page;
2990	}
2991
2992	/*
2993	* Back out if somebody else already faulted in this pte.
2994	*/
2995	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2996	if (unlikely(!pte_same(*page_table, orig_pte)))
2997	goto out_nomap;
2998
2999	if (unlikely(!PageUptodate(page))) {
3000	ret = VM_FAULT_SIGBUS;
3001	goto out_nomap;
3002	}
3003
3004	/*
3005	* The page isn't present yet, go ahead with the fault.
3006	*
3007	* Be careful about the sequence of operations here.
3008	* To get its accounting right, reuse_swap_page() must be called
3009	* while the page is counted on swap but not yet in mapcount i.e.
3010	* before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3011	* must be called after the swap_free(), or it will never succeed.
3012	* Because delete_from_swap_page() may be called by reuse_swap_page(),
3013	* mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
3014	* in page->private. In this case, a record in swap_cgroup is silently
3015	* discarded at swap_free().
3016	*/
3017
3018	inc_mm_counter_fast(mm, MM_ANONPAGES);
3019	dec_mm_counter_fast(mm, MM_SWAPENTS);
3020	pte = mk_pte(page, vma->vm_page_prot);
3021	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
3022	pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3023	flags &= ~FAULT_FLAG_WRITE;
3024	ret \|= VM_FAULT_WRITE;
3025	exclusive = 1;
3026	}
3027	flush_icache_page(vma, page);
3028	set_pte_at(mm, address, page_table, pte);
3029	do_page_add_anon_rmap(page, vma, address, exclusive);
3030	/* It's better to call commit-charge after rmap is established */
3031	mem_cgroup_commit_charge_swapin(page, ptr);
3032
3033	swap_free(entry);
3034	if (vm_swap_full() \|\| (vma->vm_flags & VM_LOCKED) \|\| PageMlocked(page))
3035	try_to_free_swap(page);
3036	unlock_page(page);
3037	if (swapcache) {
3038	/*
3039	* Hold the lock to avoid the swap entry to be reused
3040	* until we take the PT lock for the pte_same() check
3041	* (to avoid false positives from pte_same). For
3042	* further safety release the lock after the swap_free
3043	* so that the swap count won't change under a
3044	* parallel locked swapcache.
3045	*/
3046	unlock_page(swapcache);
3047	page_cache_release(swapcache);
3048	}
3049
3050	if (flags & FAULT_FLAG_WRITE) {
3051	ret \|= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3052	if (ret & VM_FAULT_ERROR)
3053	ret &= VM_FAULT_ERROR;
3054	goto out;
3055	}
3056
3057	/* No need to invalidate - it was non-present before */
3058	update_mmu_cache(vma, address, page_table);
3059	unlock:
3060	pte_unmap_unlock(page_table, ptl);
3061	out:
3062	return ret;
3063	out_nomap:
3064	mem_cgroup_cancel_charge_swapin(ptr);
3065	pte_unmap_unlock(page_table, ptl);
3066	out_page:
3067	unlock_page(page);
3068	out_release:
3069	page_cache_release(page);
3070	if (swapcache) {
3071	unlock_page(swapcache);
3072	page_cache_release(swapcache);
3073	}
3074	return ret;
3075	}
3076
3077	/*
3078	* This is like a special single-page "expand_{down\|up}wards()",
3079	* except we must first make sure that 'address{-\|+}PAGE_SIZE'
3080	* doesn't hit another vma.
3081	*/
3082	static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3083	{
3084	address &= PAGE_MASK;
3085	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3086	struct vm_area_struct *prev = vma->vm_prev;
3087
3088	/*
3089	* Is there a mapping abutting this one below?
3090	*
3091	* That's only ok if it's the same stack mapping
3092	* that has gotten split..
3093	*/
3094	if (prev && prev->vm_end == address)
3095	return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3096
3097	expand_downwards(vma, address - PAGE_SIZE);
3098	}
3099	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3100	struct vm_area_struct *next = vma->vm_next;
3101
3102	/* As VM_GROWSDOWN but s/below/above/ */
3103	if (next && next->vm_start == address + PAGE_SIZE)
3104	return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3105
3106	expand_upwards(vma, address + PAGE_SIZE);
3107	}
3108	return 0;
3109	}
3110
3111	/*
3112	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3113	* but allow concurrent faults), and pte mapped but not yet locked.
3114	* We return with mmap_sem still held, but pte unmapped and unlocked.
3115	*/
3116	static int do_anonymous_page(struct mm_struct mm, struct vm_area_struct vma,
3117	unsigned long address, pte_t page_table, pmd_t pmd,
3118	unsigned int flags)
3119	{
3120	struct page *page;
3121	spinlock_t *ptl;
3122	pte_t entry;
3123
3124	pte_unmap(page_table);
3125
3126	/* Check if we need to add a guard page to the stack */
3127	if (check_stack_guard_page(vma, address) < 0)
3128	return VM_FAULT_SIGBUS;
3129
3130	/* Use the zero-page for reads */
3131	if (!(flags & FAULT_FLAG_WRITE)) {
3132	entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3133	vma->vm_page_prot));
3134	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3135	if (!pte_none(*page_table))
3136	goto unlock;
3137	goto setpte;
3138	}
3139
3140	/* Allocate our own private page. */
3141	if (unlikely(anon_vma_prepare(vma)))
3142	goto oom;
3143	page = alloc_zeroed_user_highpage_movable(vma, address);
3144	if (!page)
3145	goto oom;
3146	__SetPageUptodate(page);
3147
3148	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3149	goto oom_free_page;
3150
3151	entry = mk_pte(page, vma->vm_page_prot);
3152	if (vma->vm_flags & VM_WRITE)
3153	entry = pte_mkwrite(pte_mkdirty(entry));
3154
3155	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3156	if (!pte_none(*page_table))
3157	goto release;
3158
3159	inc_mm_counter_fast(mm, MM_ANONPAGES);
3160	page_add_new_anon_rmap(page, vma, address);
3161	setpte:
3162	set_pte_at(mm, address, page_table, entry);
3163
3164	/* No need to invalidate - it was non-present before */
3165	update_mmu_cache(vma, address, page_table);
3166	unlock:
3167	pte_unmap_unlock(page_table, ptl);
3168	return 0;
3169	release:
3170	mem_cgroup_uncharge_page(page);
3171	page_cache_release(page);
3172	goto unlock;
3173	oom_free_page:
3174	page_cache_release(page);
3175	oom:
3176	return VM_FAULT_OOM;
3177	}
3178
3179	/*
3180	* __do_fault() tries to create a new page mapping. It aggressively
3181	* tries to share with existing pages, but makes a separate copy if
3182	* the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3183	* the next page fault.
3184	*
3185	* As this is called only for pages that do not currently exist, we
3186	* do not need to flush old virtual caches or the TLB.
3187	*
3188	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3189	* but allow concurrent faults), and pte neither mapped nor locked.
3190	* We return with mmap_sem still held, but pte unmapped and unlocked.
3191	*/
3192	static int __do_fault(struct mm_struct mm, struct vm_area_struct vma,
3193	unsigned long address, pmd_t *pmd,
3194	pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3195	{
3196	pte_t *page_table;
3197	spinlock_t *ptl;
3198	struct page *page;
3199	struct page *cow_page;
3200	pte_t entry;
3201	int anon = 0;
3202	struct page *dirty_page = NULL;
3203	struct vm_fault vmf;
3204	int ret;
3205	int page_mkwrite = 0;
3206
3207	/*
3208	* If we do COW later, allocate page befor taking lock_page()
3209	* on the file cache page. This will reduce lock holding time.
3210	*/
3211	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
3212
3213	if (unlikely(anon_vma_prepare(vma)))
3214	return VM_FAULT_OOM;
3215
3216	cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3217	if (!cow_page)
3218	return VM_FAULT_OOM;
3219
3220	if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
3221	page_cache_release(cow_page);
3222	return VM_FAULT_OOM;
3223	}
3224	} else
3225	cow_page = NULL;
3226
3227	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3228	vmf.pgoff = pgoff;
3229	vmf.flags = flags;
3230	vmf.page = NULL;
3231
3232	ret = vma->vm_ops->fault(vma, &vmf);
3233	if (unlikely(ret & (VM_FAULT_ERROR \| VM_FAULT_NOPAGE \|
3234	VM_FAULT_RETRY)))
3235	goto uncharge_out;
3236
3237	if (unlikely(PageHWPoison(vmf.page))) {
3238	if (ret & VM_FAULT_LOCKED)
3239	unlock_page(vmf.page);
3240	ret = VM_FAULT_HWPOISON;
3241	goto uncharge_out;
3242	}
3243
3244	/*
3245	* For consistency in subsequent calls, make the faulted page always
3246	* locked.
3247	*/
3248	if (unlikely(!(ret & VM_FAULT_LOCKED)))
3249	lock_page(vmf.page);
3250	else
3251	VM_BUG_ON(!PageLocked(vmf.page));
3252
3253	/*
3254	* Should we do an early C-O-W break?
3255	*/
3256	page = vmf.page;
3257	if (flags & FAULT_FLAG_WRITE) {
3258	if (!(vma->vm_flags & VM_SHARED)) {
3259	page = cow_page;
3260	anon = 1;
3261	copy_user_highpage(page, vmf.page, address, vma);
3262	__SetPageUptodate(page);
3263	} else {
3264	/*
3265	* If the page will be shareable, see if the backing
3266	* address space wants to know that the page is about
3267	* to become writable
3268	*/
3269	if (vma->vm_ops->page_mkwrite) {
3270	int tmp;
3271
3272	unlock_page(page);
3273	vmf.flags = FAULT_FLAG_WRITE\|FAULT_FLAG_MKWRITE;
3274	tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3275	if (unlikely(tmp &
3276	(VM_FAULT_ERROR \| VM_FAULT_NOPAGE))) {
3277	ret = tmp;
3278	goto unwritable_page;
3279	}
3280	if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3281	lock_page(page);
3282	if (!page->mapping) {
3283	ret = 0; /* retry the fault */
3284	unlock_page(page);
3285	goto unwritable_page;
3286	}
3287	} else
3288	VM_BUG_ON(!PageLocked(page));
3289	page_mkwrite = 1;
3290	}
3291	}
3292
3293	}
3294
3295	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3296
3297	/*
3298	* This silly early PAGE_DIRTY setting removes a race
3299	* due to the bad i386 page protection. But it's valid
3300	* for other architectures too.
3301	*
3302	* Note that if FAULT_FLAG_WRITE is set, we either now have
3303	* an exclusive copy of the page, or this is a shared mapping,
3304	* so we can make it writable and dirty to avoid having to
3305	* handle that later.
3306	*/
3307	/* Only go through if we didn't race with anybody else... */
3308	if (likely(pte_same(*page_table, orig_pte))) {
3309	flush_icache_page(vma, page);
3310	entry = mk_pte(page, vma->vm_page_prot);
3311	if (flags & FAULT_FLAG_WRITE)
3312	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3313	if (anon) {
3314	inc_mm_counter_fast(mm, MM_ANONPAGES);
3315	page_add_new_anon_rmap(page, vma, address);
3316	} else {
3317	inc_mm_counter_fast(mm, MM_FILEPAGES);
3318	page_add_file_rmap(page);
3319	if (flags & FAULT_FLAG_WRITE) {
3320	dirty_page = page;
3321	get_page(dirty_page);
3322	}
3323	}
3324	set_pte_at(mm, address, page_table, entry);
3325
3326	/* no need to invalidate: a not-present page won't be cached */
3327	update_mmu_cache(vma, address, page_table);
3328	} else {
3329	if (cow_page)
3330	mem_cgroup_uncharge_page(cow_page);
3331	if (anon)
3332	page_cache_release(page);
3333	else
3334	anon = 1; /* no anon but release faulted_page */
3335	}
3336
3337	pte_unmap_unlock(page_table, ptl);
3338
3339	if (dirty_page) {
3340	struct address_space *mapping = page->mapping;
3341	int dirtied = 0;
3342
3343	if (set_page_dirty(dirty_page))
3344	dirtied = 1;
3345	unlock_page(dirty_page);
3346	put_page(dirty_page);
3347	if ((dirtied \|\| page_mkwrite) && mapping) {
3348	/*
3349	* Some device drivers do not set page.mapping but still
3350	* dirty their pages
3351	*/
3352	balance_dirty_pages_ratelimited(mapping);
3353	}
3354
3355	/* file_update_time outside page_lock */
3356	if (vma->vm_file && !page_mkwrite)
3357	file_update_time(vma->vm_file);
3358	} else {
3359	unlock_page(vmf.page);
3360	if (anon)
3361	page_cache_release(vmf.page);
3362	}
3363
3364	return ret;
3365
3366	unwritable_page:
3367	page_cache_release(page);
3368	return ret;
3369	uncharge_out:
3370	/* fs's fault handler get error */
3371	if (cow_page) {
3372	mem_cgroup_uncharge_page(cow_page);
3373	page_cache_release(cow_page);
3374	}
3375	return ret;
3376	}
3377
3378	static int do_linear_fault(struct mm_struct mm, struct vm_area_struct vma,
3379	unsigned long address, pte_t page_table, pmd_t pmd,
3380	unsigned int flags, pte_t orig_pte)
3381	{
3382	pgoff_t pgoff = (((address & PAGE_MASK)
3383	- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3384
3385	pte_unmap(page_table);
3386	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3387	}
3388
3389	/*
3390	* Fault of a previously existing named mapping. Repopulate the pte
3391	* from the encoded file_pte if possible. This enables swappable
3392	* nonlinear vmas.
3393	*
3394	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3395	* but allow concurrent faults), and pte mapped but not yet locked.
3396	* We return with mmap_sem still held, but pte unmapped and unlocked.
3397	*/
3398	static int do_nonlinear_fault(struct mm_struct mm, struct vm_area_struct vma,
3399	unsigned long address, pte_t page_table, pmd_t pmd,
3400	unsigned int flags, pte_t orig_pte)
3401	{
3402	pgoff_t pgoff;
3403
3404	flags \|= FAULT_FLAG_NONLINEAR;
3405
3406	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3407	return 0;
3408
3409	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3410	/*
3411	* Page table corrupted: show pte and kill process.
3412	*/
3413	print_bad_pte(vma, address, orig_pte, NULL);
3414	return VM_FAULT_SIGBUS;
3415	}
3416
3417	pgoff = pte_to_pgoff(orig_pte);
3418	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3419	}
3420
3421	/*
3422	* These routines also need to handle stuff like marking pages dirty
3423	* and/or accessed for architectures that don't do it in hardware (most
3424	* RISC architectures). The early dirtying is also good on the i386.
3425	*
3426	* There is also a hook called "update_mmu_cache()" that architectures
3427	* with external mmu caches can use to update those (ie the Sparc or
3428	* PowerPC hashed page tables that act as extended TLBs).
3429	*
3430	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3431	* but allow concurrent faults), and pte mapped but not yet locked.
3432	* We return with mmap_sem still held, but pte unmapped and unlocked.
3433	*/
3434	int handle_pte_fault(struct mm_struct *mm,
3435	struct vm_area_struct *vma, unsigned long address,
3436	pte_t pte, pmd_t pmd, unsigned int flags)
3437	{
3438	pte_t entry;
3439	spinlock_t *ptl;
3440
3441	entry = *pte;
3442	if (!pte_present(entry)) {
3443	if (pte_none(entry)) {
3444	if (vma->vm_ops) {
3445	if (likely(vma->vm_ops->fault))
3446	return do_linear_fault(mm, vma, address,
3447	pte, pmd, flags, entry);
3448	}
3449	return do_anonymous_page(mm, vma, address,
3450	pte, pmd, flags);
3451	}
3452	if (pte_file(entry))
3453	return do_nonlinear_fault(mm, vma, address,
3454	pte, pmd, flags, entry);
3455	return do_swap_page(mm, vma, address,
3456	pte, pmd, flags, entry);
3457	}
3458
3459	ptl = pte_lockptr(mm, pmd);
3460	spin_lock(ptl);
3461	if (unlikely(!pte_same(*pte, entry)))
3462	goto unlock;
3463	if (flags & FAULT_FLAG_WRITE) {
3464	if (!pte_write(entry))
3465	return do_wp_page(mm, vma, address,
3466	pte, pmd, ptl, entry);
3467	entry = pte_mkdirty(entry);
3468	}
3469	entry = pte_mkyoung(entry);
3470	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3471	update_mmu_cache(vma, address, pte);
3472	} else {
3473	/*
3474	* This is needed only for protection faults but the arch code
3475	* is not yet telling us if this is a protection fault or not.
3476	* This still avoids useless tlb flushes for .text page faults
3477	* with threads.
3478	*/
3479	if (flags & FAULT_FLAG_WRITE)
3480	flush_tlb_fix_spurious_fault(vma, address);
3481	}
3482	unlock:
3483	pte_unmap_unlock(pte, ptl);
3484	return 0;
3485	}
3486
3487	/*
3488	* By the time we get here, we already hold the mm semaphore
3489	*/
3490	int handle_mm_fault(struct mm_struct mm, struct vm_area_struct vma,
3491	unsigned long address, unsigned int flags)
3492	{
3493	pgd_t *pgd;
3494	pud_t *pud;
3495	pmd_t *pmd;
3496	pte_t *pte;
3497
3498	__set_current_state(TASK_RUNNING);
3499
3500	count_vm_event(PGFAULT);
3501	mem_cgroup_count_vm_event(mm, PGFAULT);
3502
3503	/* do counter updates before entering really critical section. */
3504	check_sync_rss_stat(current);
3505
3506	if (unlikely(is_vm_hugetlb_page(vma)))
3507	return hugetlb_fault(mm, vma, address, flags);
3508
3509	retry:
3510	pgd = pgd_offset(mm, address);
3511	pud = pud_alloc(mm, pgd, address);
3512	if (!pud)
3513	return VM_FAULT_OOM;
3514	pmd = pmd_alloc(mm, pud, address);
3515	if (!pmd)
3516	return VM_FAULT_OOM;
3517	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3518	if (!vma->vm_ops)
3519	return do_huge_pmd_anonymous_page(mm, vma, address,
3520	pmd, flags);
3521	} else {
3522	pmd_t orig_pmd = *pmd;
3523	int ret;
3524
3525	barrier();
3526	if (pmd_trans_huge(orig_pmd)) {
3527	if (flags & FAULT_FLAG_WRITE &&
3528	!pmd_write(orig_pmd) &&
3529	!pmd_trans_splitting(orig_pmd)) {
3530	ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
3531	orig_pmd);
3532	/*
3533	* If COW results in an oom, the huge pmd will
3534	* have been split, so retry the fault on the
3535	* pte for a smaller charge.
3536	*/
3537	if (unlikely(ret & VM_FAULT_OOM))
3538	goto retry;
3539	return ret;
3540	}
3541	return 0;
3542	}
3543	}
3544
3545	/*
3546	* Use __pte_alloc instead of pte_alloc_map, because we can't
3547	* run pte_offset_map on the pmd, if an huge pmd could
3548	* materialize from under us from a different thread.
3549	*/
3550	if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
3551	return VM_FAULT_OOM;
3552	/* if an huge pmd materialized from under us just retry later */
3553	if (unlikely(pmd_trans_huge(*pmd)))
3554	return 0;
3555	/*
3556	* A regular pmd is established and it can't morph into a huge pmd
3557	* from under us anymore at this point because we hold the mmap_sem
3558	* read mode and khugepaged takes it in write mode. So now it's
3559	* safe to run pte_offset_map().
3560	*/
3561	pte = pte_offset_map(pmd, address);
3562
3563	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3564	}
3565
3566	#ifndef __PAGETABLE_PUD_FOLDED
3567	/*
3568	* Allocate page upper directory.
3569	* We've already handled the fast-path in-line.
3570	*/
3571	int __pud_alloc(struct mm_struct mm, pgd_t pgd, unsigned long address)
3572	{
3573	pud_t *new = pud_alloc_one(mm, address);
3574	if (!new)
3575	return -ENOMEM;
3576
3577	smp_wmb(); /* See comment in __pte_alloc */
3578
3579	spin_lock(&mm->page_table_lock);
3580	if (pgd_present(pgd)) / Another has populated it */
3581	pud_free(mm, new);
3582	else
3583	pgd_populate(mm, pgd, new);
3584	spin_unlock(&mm->page_table_lock);
3585	return 0;
3586	}
3587	#endif /* __PAGETABLE_PUD_FOLDED */
3588
3589	#ifndef __PAGETABLE_PMD_FOLDED
3590	/*
3591	* Allocate page middle directory.
3592	* We've already handled the fast-path in-line.
3593	*/
3594	int __pmd_alloc(struct mm_struct mm, pud_t pud, unsigned long address)
3595	{
3596	pmd_t *new = pmd_alloc_one(mm, address);
3597	if (!new)
3598	return -ENOMEM;
3599
3600	smp_wmb(); /* See comment in __pte_alloc */
3601
3602	spin_lock(&mm->page_table_lock);
3603	#ifndef __ARCH_HAS_4LEVEL_HACK
3604	if (pud_present(pud)) / Another has populated it */
3605	pmd_free(mm, new);
3606	else
3607	pud_populate(mm, pud, new);
3608	#else
3609	if (pgd_present(pud)) / Another has populated it */
3610	pmd_free(mm, new);
3611	else
3612	pgd_populate(mm, pud, new);
3613	#endif /* __ARCH_HAS_4LEVEL_HACK */
3614	spin_unlock(&mm->page_table_lock);
3615	return 0;
3616	}
3617	#endif /* __PAGETABLE_PMD_FOLDED */
3618
3619	int make_pages_present(unsigned long addr, unsigned long end)
3620	{
3621	int ret, len, write;
3622	struct vm_area_struct * vma;
3623
3624	vma = find_vma(current->mm, addr);
3625	if (!vma)
3626	return -ENOMEM;
3627	/*
3628	* We want to touch writable mappings with a write fault in order
3629	* to break COW, except for shared mappings because these don't COW
3630	* and we would not want to dirty them for nothing.
3631	*/
3632	write = (vma->vm_flags & (VM_WRITE \| VM_SHARED)) == VM_WRITE;
3633	BUG_ON(addr >= end);
3634	BUG_ON(end > vma->vm_end);
3635	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3636	ret = get_user_pages(current, current->mm, addr,
3637	len, write, 0, NULL, NULL);
3638	if (ret < 0)
3639	return ret;
3640	return ret == len ? 0 : -EFAULT;
3641	}
3642
3643	#if !defined(__HAVE_ARCH_GATE_AREA)
3644
3645	#if defined(AT_SYSINFO_EHDR)
3646	static struct vm_area_struct gate_vma;
3647
3648	static int __init gate_vma_init(void)
3649	{
3650	gate_vma.vm_mm = NULL;
3651	gate_vma.vm_start = FIXADDR_USER_START;
3652	gate_vma.vm_end = FIXADDR_USER_END;
3653	gate_vma.vm_flags = VM_READ \| VM_MAYREAD \| VM_EXEC \| VM_MAYEXEC;
3654	gate_vma.vm_page_prot = __P101;
3655
3656	return 0;
3657	}
3658	__initcall(gate_vma_init);
3659	#endif
3660
3661	struct vm_area_struct get_gate_vma(struct mm_struct mm)
3662	{
3663	#ifdef AT_SYSINFO_EHDR
3664	return &gate_vma;
3665	#else
3666	return NULL;
3667	#endif
3668	}
3669
3670	int in_gate_area_no_mm(unsigned long addr)
3671	{
3672	#ifdef AT_SYSINFO_EHDR
3673	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3674	return 1;
3675	#endif
3676	return 0;
3677	}
3678
3679	#endif /* __HAVE_ARCH_GATE_AREA */
3680
3681	static int __follow_pte(struct mm_struct *mm, unsigned long address,
3682	pte_t ptepp, spinlock_t ptlp)
3683	{
3684	pgd_t *pgd;
3685	pud_t *pud;
3686	pmd_t *pmd;
3687	pte_t *ptep;
3688
3689	pgd = pgd_offset(mm, address);
3690	if (pgd_none(pgd) \|\| unlikely(pgd_bad(pgd)))
3691	goto out;
3692
3693	pud = pud_offset(pgd, address);
3694	if (pud_none(pud) \|\| unlikely(pud_bad(pud)))
3695	goto out;
3696
3697	pmd = pmd_offset(pud, address);
3698	VM_BUG_ON(pmd_trans_huge(*pmd));
3699	if (pmd_none(pmd) \|\| unlikely(pmd_bad(pmd)))
3700	goto out;
3701
3702	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
3703	if (pmd_huge(*pmd))
3704	goto out;
3705
3706	ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3707	if (!ptep)
3708	goto out;
3709	if (!pte_present(*ptep))
3710	goto unlock;
3711	*ptepp = ptep;
3712	return 0;
3713	unlock:
3714	pte_unmap_unlock(ptep, *ptlp);
3715	out:
3716	return -EINVAL;
3717	}
3718
3719	static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3720	pte_t ptepp, spinlock_t ptlp)
3721	{
3722	int res;
3723
3724	/* (void) is needed to make gcc happy */
3725	(void) __cond_lock(*ptlp,
3726	!(res = __follow_pte(mm, address, ptepp, ptlp)));
3727	return res;
3728	}
3729
3730	/**
3731	* follow_pfn - look up PFN at a user virtual address
3732	* @vma: memory mapping
3733	* @address: user virtual address
3734	* @pfn: location to store found PFN
3735	*
3736	* Only IO mappings and raw PFN mappings are allowed.
3737	*
3738	* Returns zero and the pfn at @pfn on success, -ve otherwise.
3739	*/
3740	int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3741	unsigned long *pfn)
3742	{
3743	int ret = -EINVAL;
3744	spinlock_t *ptl;
3745	pte_t *ptep;
3746
3747	if (!(vma->vm_flags & (VM_IO \| VM_PFNMAP)))
3748	return ret;
3749
3750	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3751	if (ret)
3752	return ret;
3753	pfn = pte_pfn(ptep);
3754	pte_unmap_unlock(ptep, ptl);
3755	return 0;
3756	}
3757	EXPORT_SYMBOL(follow_pfn);
3758
3759	#ifdef CONFIG_HAVE_IOREMAP_PROT
3760	int follow_phys(struct vm_area_struct *vma,
3761	unsigned long address, unsigned int flags,
3762	unsigned long prot, resource_size_t phys)
3763	{
3764	int ret = -EINVAL;
3765	pte_t *ptep, pte;
3766	spinlock_t *ptl;
3767
3768	if (!(vma->vm_flags & (VM_IO \| VM_PFNMAP)))
3769	goto out;
3770
3771	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3772	goto out;
3773	pte = *ptep;
3774
3775	if ((flags & FOLL_WRITE) && !pte_write(pte))
3776	goto unlock;
3777
3778	*prot = pgprot_val(pte_pgprot(pte));
3779	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3780
3781	ret = 0;
3782	unlock:
3783	pte_unmap_unlock(ptep, ptl);
3784	out:
3785	return ret;
3786	}
3787
3788	int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3789	void *buf, int len, int write)
3790	{
3791	resource_size_t phys_addr;
3792	unsigned long prot = 0;
3793	void __iomem *maddr;
3794	int offset = addr & (PAGE_SIZE-1);
3795
3796	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3797	return -EINVAL;
3798
3799	maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3800	if (write)
3801	memcpy_toio(maddr + offset, buf, len);
3802	else
3803	memcpy_fromio(buf, maddr + offset, len);
3804	iounmap(maddr);
3805
3806	return len;
3807	}
3808	#endif
3809
3810	/*
3811	* Access another process' address space as given in mm. If non-NULL, use the
3812	* given task for page fault accounting.
3813	*/
3814	static int __access_remote_vm(struct task_struct tsk, struct mm_struct mm,
3815	unsigned long addr, void *buf, int len, int write)
3816	{
3817	struct vm_area_struct *vma;
3818	void *old_buf = buf;
3819
3820	down_read(&mm->mmap_sem);
3821	/* ignore errors, just check how much was successfully transferred */
3822	while (len) {
3823	int bytes, ret, offset;
3824	void *maddr;
3825	struct page *page = NULL;
3826
3827	ret = get_user_pages(tsk, mm, addr, 1,
3828	write, 1, &page, &vma);
3829	if (ret <= 0) {
3830	/*
3831	* Check if this is a VM_IO \| VM_PFNMAP VMA, which
3832	* we can access using slightly different code.
3833	*/
3834	#ifdef CONFIG_HAVE_IOREMAP_PROT
3835	vma = find_vma(mm, addr);
3836	if (!vma \|\| vma->vm_start > addr)
3837	break;
3838	if (vma->vm_ops && vma->vm_ops->access)
3839	ret = vma->vm_ops->access(vma, addr, buf,
3840	len, write);
3841	if (ret <= 0)
3842	#endif
3843	break;
3844	bytes = ret;
3845	} else {
3846	bytes = len;
3847	offset = addr & (PAGE_SIZE-1);
3848	if (bytes > PAGE_SIZE-offset)
3849	bytes = PAGE_SIZE-offset;
3850
3851	maddr = kmap(page);
3852	if (write) {
3853	copy_to_user_page(vma, page, addr,
3854	maddr + offset, buf, bytes);
3855	set_page_dirty_lock(page);
3856	} else {
3857	copy_from_user_page(vma, page, addr,
3858	buf, maddr + offset, bytes);
3859	}
3860	kunmap(page);
3861	page_cache_release(page);
3862	}
3863	len -= bytes;
3864	buf += bytes;
3865	addr += bytes;
3866	}
3867	up_read(&mm->mmap_sem);
3868
3869	return buf - old_buf;
3870	}
3871
3872	/**
3873	* access_remote_vm - access another process' address space
3874	* @mm: the mm_struct of the target address space
3875	* @addr: start address to access
3876	* @buf: source or destination buffer
3877	* @len: number of bytes to transfer
3878	* @write: whether the access is a write
3879	*
3880	* The caller must hold a reference on @mm.
3881	*/
3882	int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3883	void *buf, int len, int write)
3884	{
3885	return __access_remote_vm(NULL, mm, addr, buf, len, write);
3886	}
3887
3888	/*
3889	* Access another process' address space.
3890	* Source/target buffer must be kernel space,
3891	* Do not walk the page table directly, use get_user_pages
3892	*/
3893	int access_process_vm(struct task_struct *tsk, unsigned long addr,
3894	void *buf, int len, int write)
3895	{
3896	struct mm_struct *mm;
3897	int ret;
3898
3899	mm = get_task_mm(tsk);
3900	if (!mm)
3901	return 0;
3902
3903	ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3904	mmput(mm);
3905
3906	return ret;
3907	}
3908
3909	/*
3910	* Print the name of a VMA.
3911	*/
3912	void print_vma_addr(char *prefix, unsigned long ip)
3913	{
3914	struct mm_struct *mm = current->mm;
3915	struct vm_area_struct *vma;
3916
3917	/*
3918	* Do not print if we are in atomic
3919	* contexts (in exception stacks, etc.):
3920	*/
3921	if (preempt_count())
3922	return;
3923
3924	down_read(&mm->mmap_sem);
3925	vma = find_vma(mm, ip);
3926	if (vma && vma->vm_file) {
3927	struct file *f = vma->vm_file;
3928	char buf = (char )__get_free_page(GFP_KERNEL);
3929	if (buf) {
3930	char p, s;
3931
3932	p = d_path(&f->f_path, buf, PAGE_SIZE);
3933	if (IS_ERR(p))
3934	p = "?";
3935	s = strrchr(p, '/');
3936	if (s)
3937	p = s+1;
3938	printk("%s%s[%lx+%lx]", prefix, p,
3939	vma->vm_start,
3940	vma->vm_end - vma->vm_start);
3941	free_page((unsigned long)buf);
3942	}
3943	}
3944	up_read(&mm->mmap_sem);
3945	}
3946
3947	#ifdef CONFIG_PROVE_LOCKING
3948	void might_fault(void)
3949	{
3950	/*
3951	* Some code (nfs/sunrpc) uses socket ops on kernel memory while
3952	* holding the mmap_sem, this is safe because kernel memory doesn't
3953	* get paged out, therefore we'll never actually fault, and the
3954	* below annotations will generate false positives.
3955	*/
3956	if (segment_eq(get_fs(), KERNEL_DS))
3957	return;
3958
3959	might_sleep();
3960	/*
3961	* it would be nicer only to annotate paths which are not under
3962	* pagefault_disable, however that requires a larger audit and
3963	* providing helpers like get_user_atomic.
3964	*/
3965	if (!in_atomic() && current->mm)
3966	might_lock_read(&current->mm->mmap_sem);
3967	}
3968	EXPORT_SYMBOL(might_fault);
3969	#endif
3970
3971	#if defined(CONFIG_TRANSPARENT_HUGEPAGE) \|\| defined(CONFIG_HUGETLBFS)
3972	static void clear_gigantic_page(struct page *page,
3973	unsigned long addr,
3974	unsigned int pages_per_huge_page)
3975	{
3976	int i;
3977	struct page *p = page;
3978
3979	might_sleep();
3980	for (i = 0; i < pages_per_huge_page;
3981	i++, p = mem_map_next(p, page, i)) {
3982	cond_resched();
3983	clear_user_highpage(p, addr + i * PAGE_SIZE);
3984	}
3985	}
3986	void clear_huge_page(struct page *page,
3987	unsigned long addr, unsigned int pages_per_huge_page)
3988	{
3989	int i;
3990
3991	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3992	clear_gigantic_page(page, addr, pages_per_huge_page);
3993	return;
3994	}
3995
3996	might_sleep();
3997	for (i = 0; i < pages_per_huge_page; i++) {
3998	cond_resched();
3999	clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4000	}
4001	}
4002
4003	static void copy_user_gigantic_page(struct page dst, struct page src,
4004	unsigned long addr,
4005	struct vm_area_struct *vma,
4006	unsigned int pages_per_huge_page)
4007	{
4008	int i;
4009	struct page *dst_base = dst;
4010	struct page *src_base = src;
4011
4012	for (i = 0; i < pages_per_huge_page; ) {
4013	cond_resched();
4014	copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4015
4016	i++;
4017	dst = mem_map_next(dst, dst_base, i);
4018	src = mem_map_next(src, src_base, i);
4019	}
4020	}
4021
4022	void copy_user_huge_page(struct page dst, struct page src,
4023	unsigned long addr, struct vm_area_struct *vma,
4024	unsigned int pages_per_huge_page)
4025	{
4026	int i;
4027
4028	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4029	copy_user_gigantic_page(dst, src, addr, vma,
4030	pages_per_huge_page);
4031	return;
4032	}
4033
4034	might_sleep();
4035	for (i = 0; i < pages_per_huge_page; i++) {
4036	cond_resched();
4037	copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4038	}
4039	}
4040	#endif /* CONFIG_TRANSPARENT_HUGEPAGE \|\| CONFIG_HUGETLBFS */
4041

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