linux - mm/memory.c

3978 lines · 107.4 KiB

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 ([email protected])
34	*
35	* 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36	* ([email protected])
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/pfn_t.h>
54	#include <linux/writeback.h>
55	#include <linux/memcontrol.h>
56	#include <linux/mmu_notifier.h>
57	#include <linux/kallsyms.h>
58	#include <linux/swapops.h>
59	#include <linux/elf.h>
60	#include <linux/gfp.h>
61	#include <linux/migrate.h>
62	#include <linux/string.h>
63	#include <linux/dma-debug.h>
64	#include <linux/debugfs.h>
65	#include <linux/userfaultfd_k.h>
66
67	#include <asm/io.h>
68	#include <asm/mmu_context.h>
69	#include <asm/pgalloc.h>
70	#include <asm/uaccess.h>
71	#include <asm/tlb.h>
72	#include <asm/tlbflush.h>
73	#include <asm/pgtable.h>
74
75	#include "internal.h"
76
77	#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
78	#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
79	#endif
80
81	#ifndef CONFIG_NEED_MULTIPLE_NODES
82	/* use the per-pgdat data instead for discontigmem - mbligh */
83	unsigned long max_mapnr;
84	struct page *mem_map;
85
86	EXPORT_SYMBOL(max_mapnr);
87	EXPORT_SYMBOL(mem_map);
88	#endif
89
90	/*
91	* A number of key systems in x86 including ioremap() rely on the assumption
92	* that high_memory defines the upper bound on direct map memory, then end
93	* of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
94	* highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
95	* and ZONE_HIGHMEM.
96	*/
97	void * high_memory;
98
99	EXPORT_SYMBOL(high_memory);
100
101	/*
102	* Randomize the address space (stacks, mmaps, brk, etc.).
103	*
104	* ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
105	* as ancient (libc5 based) binaries can segfault. )
106	*/
107	int randomize_va_space __read_mostly =
108	#ifdef CONFIG_COMPAT_BRK
109	1;
110	#else
111	2;
112	#endif
113
114	static int __init disable_randmaps(char *s)
115	{
116	randomize_va_space = 0;
117	return 1;
118	}
119	__setup("norandmaps", disable_randmaps);
120
121	unsigned long zero_pfn __read_mostly;
122	unsigned long highest_memmap_pfn __read_mostly;
123
124	EXPORT_SYMBOL(zero_pfn);
125
126	/*
127	* CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
128	*/
129	static int __init init_zero_pfn(void)
130	{
131	zero_pfn = page_to_pfn(ZERO_PAGE(0));
132	return 0;
133	}
134	core_initcall(init_zero_pfn);
135
136
137	#if defined(SPLIT_RSS_COUNTING)
138
139	void sync_mm_rss(struct mm_struct *mm)
140	{
141	int i;
142
143	for (i = 0; i < NR_MM_COUNTERS; i++) {
144	if (current->rss_stat.count[i]) {
145	add_mm_counter(mm, i, current->rss_stat.count[i]);
146	current->rss_stat.count[i] = 0;
147	}
148	}
149	current->rss_stat.events = 0;
150	}
151
152	static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
153	{
154	struct task_struct *task = current;
155
156	if (likely(task->mm == mm))
157	task->rss_stat.count[member] += val;
158	else
159	add_mm_counter(mm, member, val);
160	}
161	#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
162	#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
163
164	/* sync counter once per 64 page faults */
165	#define TASK_RSS_EVENTS_THRESH (64)
166	static void check_sync_rss_stat(struct task_struct *task)
167	{
168	if (unlikely(task != current))
169	return;
170	if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
171	sync_mm_rss(task->mm);
172	}
173	#else /* SPLIT_RSS_COUNTING */
174
175	#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
176	#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
177
178	static void check_sync_rss_stat(struct task_struct *task)
179	{
180	}
181
182	#endif /* SPLIT_RSS_COUNTING */
183
184	#ifdef HAVE_GENERIC_MMU_GATHER
185
186	static bool tlb_next_batch(struct mmu_gather *tlb)
187	{
188	struct mmu_gather_batch *batch;
189
190	batch = tlb->active;
191	if (batch->next) {
192	tlb->active = batch->next;
193	return true;
194	}
195
196	if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
197	return false;
198
199	batch = (void *)__get_free_pages(GFP_NOWAIT \| __GFP_NOWARN, 0);
200	if (!batch)
201	return false;
202
203	tlb->batch_count++;
204	batch->next = NULL;
205	batch->nr = 0;
206	batch->max = MAX_GATHER_BATCH;
207
208	tlb->active->next = batch;
209	tlb->active = batch;
210
211	return true;
212	}
213
214	/* tlb_gather_mmu
215	* Called to initialize an (on-stack) mmu_gather structure for page-table
216	* tear-down from @mm. The @fullmm argument is used when @mm is without
217	* users and we're going to destroy the full address space (exit/execve).
218	*/
219	void tlb_gather_mmu(struct mmu_gather tlb, struct mm_struct mm, unsigned long start, unsigned long end)
220	{
221	tlb->mm = mm;
222
223	/* Is it from 0 to ~0? */
224	tlb->fullmm = !(start \| (end+1));
225	tlb->need_flush_all = 0;
226	tlb->local.next = NULL;
227	tlb->local.nr = 0;
228	tlb->local.max = ARRAY_SIZE(tlb->__pages);
229	tlb->active = &tlb->local;
230	tlb->batch_count = 0;
231
232	#ifdef CONFIG_HAVE_RCU_TABLE_FREE
233	tlb->batch = NULL;
234	#endif
235
236	__tlb_reset_range(tlb);
237	}
238
239	static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
240	{
241	if (!tlb->end)
242	return;
243
244	tlb_flush(tlb);
245	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
246	#ifdef CONFIG_HAVE_RCU_TABLE_FREE
247	tlb_table_flush(tlb);
248	#endif
249	__tlb_reset_range(tlb);
250	}
251
252	static void tlb_flush_mmu_free(struct mmu_gather *tlb)
253	{
254	struct mmu_gather_batch *batch;
255
256	for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
257	free_pages_and_swap_cache(batch->pages, batch->nr);
258	batch->nr = 0;
259	}
260	tlb->active = &tlb->local;
261	}
262
263	void tlb_flush_mmu(struct mmu_gather *tlb)
264	{
265	tlb_flush_mmu_tlbonly(tlb);
266	tlb_flush_mmu_free(tlb);
267	}
268
269	/* tlb_finish_mmu
270	* Called at the end of the shootdown operation to free up any resources
271	* that were required.
272	*/
273	void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
274	{
275	struct mmu_gather_batch batch, next;
276
277	tlb_flush_mmu(tlb);
278
279	/* keep the page table cache within bounds */
280	check_pgt_cache();
281
282	for (batch = tlb->local.next; batch; batch = next) {
283	next = batch->next;
284	free_pages((unsigned long)batch, 0);
285	}
286	tlb->local.next = NULL;
287	}
288
289	/* __tlb_remove_page
290	* Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
291	* handling the additional races in SMP caused by other CPUs caching valid
292	* mappings in their TLBs. Returns the number of free page slots left.
293	* When out of page slots we must call tlb_flush_mmu().
294	*/
295	int __tlb_remove_page(struct mmu_gather tlb, struct page page)
296	{
297	struct mmu_gather_batch *batch;
298
299	VM_BUG_ON(!tlb->end);
300
301	batch = tlb->active;
302	batch->pages[batch->nr++] = page;
303	if (batch->nr == batch->max) {
304	if (!tlb_next_batch(tlb))
305	return 0;
306	batch = tlb->active;
307	}
308	VM_BUG_ON_PAGE(batch->nr > batch->max, page);
309
310	return batch->max - batch->nr;
311	}
312
313	#endif /* HAVE_GENERIC_MMU_GATHER */
314
315	#ifdef CONFIG_HAVE_RCU_TABLE_FREE
316
317	/*
318	* See the comment near struct mmu_table_batch.
319	*/
320
321	static void tlb_remove_table_smp_sync(void *arg)
322	{
323	/* Simply deliver the interrupt */
324	}
325
326	static void tlb_remove_table_one(void *table)
327	{
328	/*
329	* This isn't an RCU grace period and hence the page-tables cannot be
330	* assumed to be actually RCU-freed.
331	*
332	* It is however sufficient for software page-table walkers that rely on
333	* IRQ disabling. See the comment near struct mmu_table_batch.
334	*/
335	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
336	__tlb_remove_table(table);
337	}
338
339	static void tlb_remove_table_rcu(struct rcu_head *head)
340	{
341	struct mmu_table_batch *batch;
342	int i;
343
344	batch = container_of(head, struct mmu_table_batch, rcu);
345
346	for (i = 0; i < batch->nr; i++)
347	__tlb_remove_table(batch->tables[i]);
348
349	free_page((unsigned long)batch);
350	}
351
352	void tlb_table_flush(struct mmu_gather *tlb)
353	{
354	struct mmu_table_batch **batch = &tlb->batch;
355
356	if (*batch) {
357	call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
358	*batch = NULL;
359	}
360	}
361
362	void tlb_remove_table(struct mmu_gather tlb, void table)
363	{
364	struct mmu_table_batch **batch = &tlb->batch;
365
366	/*
367	* When there's less then two users of this mm there cannot be a
368	* concurrent page-table walk.
369	*/
370	if (atomic_read(&tlb->mm->mm_users) < 2) {
371	__tlb_remove_table(table);
372	return;
373	}
374
375	if (*batch == NULL) {
376	batch = (struct mmu_table_batch )__get_free_page(GFP_NOWAIT \| __GFP_NOWARN);
377	if (*batch == NULL) {
378	tlb_remove_table_one(table);
379	return;
380	}
381	(*batch)->nr = 0;
382	}
383	(batch)->tables[(batch)->nr++] = table;
384	if ((*batch)->nr == MAX_TABLE_BATCH)
385	tlb_table_flush(tlb);
386	}
387
388	#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
389
390	/*
391	* Note: this doesn't free the actual pages themselves. That
392	* has been handled earlier when unmapping all the memory regions.
393	*/
394	static void free_pte_range(struct mmu_gather tlb, pmd_t pmd,
395	unsigned long addr)
396	{
397	pgtable_t token = pmd_pgtable(*pmd);
398	pmd_clear(pmd);
399	pte_free_tlb(tlb, token, addr);
400	atomic_long_dec(&tlb->mm->nr_ptes);
401	}
402
403	static inline void free_pmd_range(struct mmu_gather tlb, pud_t pud,
404	unsigned long addr, unsigned long end,
405	unsigned long floor, unsigned long ceiling)
406	{
407	pmd_t *pmd;
408	unsigned long next;
409	unsigned long start;
410
411	start = addr;
412	pmd = pmd_offset(pud, addr);
413	do {
414	next = pmd_addr_end(addr, end);
415	if (pmd_none_or_clear_bad(pmd))
416	continue;
417	free_pte_range(tlb, pmd, addr);
418	} while (pmd++, addr = next, addr != end);
419
420	start &= PUD_MASK;
421	if (start < floor)
422	return;
423	if (ceiling) {
424	ceiling &= PUD_MASK;
425	if (!ceiling)
426	return;
427	}
428	if (end - 1 > ceiling - 1)
429	return;
430
431	pmd = pmd_offset(pud, start);
432	pud_clear(pud);
433	pmd_free_tlb(tlb, pmd, start);
434	mm_dec_nr_pmds(tlb->mm);
435	}
436
437	static inline void free_pud_range(struct mmu_gather tlb, pgd_t pgd,
438	unsigned long addr, unsigned long end,
439	unsigned long floor, unsigned long ceiling)
440	{
441	pud_t *pud;
442	unsigned long next;
443	unsigned long start;
444
445	start = addr;
446	pud = pud_offset(pgd, addr);
447	do {
448	next = pud_addr_end(addr, end);
449	if (pud_none_or_clear_bad(pud))
450	continue;
451	free_pmd_range(tlb, pud, addr, next, floor, ceiling);
452	} while (pud++, addr = next, addr != end);
453
454	start &= PGDIR_MASK;
455	if (start < floor)
456	return;
457	if (ceiling) {
458	ceiling &= PGDIR_MASK;
459	if (!ceiling)
460	return;
461	}
462	if (end - 1 > ceiling - 1)
463	return;
464
465	pud = pud_offset(pgd, start);
466	pgd_clear(pgd);
467	pud_free_tlb(tlb, pud, start);
468	}
469
470	/*
471	* This function frees user-level page tables of a process.
472	*/
473	void free_pgd_range(struct mmu_gather *tlb,
474	unsigned long addr, unsigned long end,
475	unsigned long floor, unsigned long ceiling)
476	{
477	pgd_t *pgd;
478	unsigned long next;
479
480	/*
481	* The next few lines have given us lots of grief...
482	*
483	* Why are we testing PMD* at this top level? Because often
484	* there will be no work to do at all, and we'd prefer not to
485	* go all the way down to the bottom just to discover that.
486	*
487	* Why all these "- 1"s? Because 0 represents both the bottom
488	* of the address space and the top of it (using -1 for the
489	* top wouldn't help much: the masks would do the wrong thing).
490	* The rule is that addr 0 and floor 0 refer to the bottom of
491	* the address space, but end 0 and ceiling 0 refer to the top
492	* Comparisons need to use "end - 1" and "ceiling - 1" (though
493	* that end 0 case should be mythical).
494	*
495	* Wherever addr is brought up or ceiling brought down, we must
496	* be careful to reject "the opposite 0" before it confuses the
497	* subsequent tests. But what about where end is brought down
498	* by PMD_SIZE below? no, end can't go down to 0 there.
499	*
500	* Whereas we round start (addr) and ceiling down, by different
501	* masks at different levels, in order to test whether a table
502	* now has no other vmas using it, so can be freed, we don't
503	* bother to round floor or end up - the tests don't need that.
504	*/
505
506	addr &= PMD_MASK;
507	if (addr < floor) {
508	addr += PMD_SIZE;
509	if (!addr)
510	return;
511	}
512	if (ceiling) {
513	ceiling &= PMD_MASK;
514	if (!ceiling)
515	return;
516	}
517	if (end - 1 > ceiling - 1)
518	end -= PMD_SIZE;
519	if (addr > end - 1)
520	return;
521
522	pgd = pgd_offset(tlb->mm, addr);
523	do {
524	next = pgd_addr_end(addr, end);
525	if (pgd_none_or_clear_bad(pgd))
526	continue;
527	free_pud_range(tlb, pgd, addr, next, floor, ceiling);
528	} while (pgd++, addr = next, addr != end);
529	}
530
531	void free_pgtables(struct mmu_gather tlb, struct vm_area_struct vma,
532	unsigned long floor, unsigned long ceiling)
533	{
534	while (vma) {
535	struct vm_area_struct *next = vma->vm_next;
536	unsigned long addr = vma->vm_start;
537
538	/*
539	* Hide vma from rmap and truncate_pagecache before freeing
540	* pgtables
541	*/
542	unlink_anon_vmas(vma);
543	unlink_file_vma(vma);
544
545	if (is_vm_hugetlb_page(vma)) {
546	hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
547	floor, next? next->vm_start: ceiling);
548	} else {
549	/*
550	* Optimization: gather nearby vmas into one call down
551	*/
552	while (next && next->vm_start <= vma->vm_end + PMD_SIZE
553	&& !is_vm_hugetlb_page(next)) {
554	vma = next;
555	next = vma->vm_next;
556	unlink_anon_vmas(vma);
557	unlink_file_vma(vma);
558	}
559	free_pgd_range(tlb, addr, vma->vm_end,
560	floor, next? next->vm_start: ceiling);
561	}
562	vma = next;
563	}
564	}
565
566	int __pte_alloc(struct mm_struct mm, pmd_t pmd, unsigned long address)
567	{
568	spinlock_t *ptl;
569	pgtable_t new = pte_alloc_one(mm, address);
570	if (!new)
571	return -ENOMEM;
572
573	/*
574	* Ensure all pte setup (eg. pte page lock and page clearing) are
575	* visible before the pte is made visible to other CPUs by being
576	* put into page tables.
577	*
578	* The other side of the story is the pointer chasing in the page
579	* table walking code (when walking the page table without locking;
580	* ie. most of the time). Fortunately, these data accesses consist
581	* of a chain of data-dependent loads, meaning most CPUs (alpha
582	* being the notable exception) will already guarantee loads are
583	* seen in-order. See the alpha page table accessors for the
584	* smp_read_barrier_depends() barriers in page table walking code.
585	*/
586	smp_wmb(); /* Could be smp_wmb__xxx(before\|after)_spin_lock */
587
588	ptl = pmd_lock(mm, pmd);
589	if (likely(pmd_none(pmd))) { / Has another populated it ? */
590	atomic_long_inc(&mm->nr_ptes);
591	pmd_populate(mm, pmd, new);
592	new = NULL;
593	}
594	spin_unlock(ptl);
595	if (new)
596	pte_free(mm, new);
597	return 0;
598	}
599
600	int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
601	{
602	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
603	if (!new)
604	return -ENOMEM;
605
606	smp_wmb(); /* See comment in __pte_alloc */
607
608	spin_lock(&init_mm.page_table_lock);
609	if (likely(pmd_none(pmd))) { / Has another populated it ? */
610	pmd_populate_kernel(&init_mm, pmd, new);
611	new = NULL;
612	}
613	spin_unlock(&init_mm.page_table_lock);
614	if (new)
615	pte_free_kernel(&init_mm, new);
616	return 0;
617	}
618
619	static inline void init_rss_vec(int *rss)
620	{
621	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
622	}
623
624	static inline void add_mm_rss_vec(struct mm_struct mm, int rss)
625	{
626	int i;
627
628	if (current->mm == mm)
629	sync_mm_rss(mm);
630	for (i = 0; i < NR_MM_COUNTERS; i++)
631	if (rss[i])
632	add_mm_counter(mm, i, rss[i]);
633	}
634
635	/*
636	* This function is called to print an error when a bad pte
637	* is found. For example, we might have a PFN-mapped pte in
638	* a region that doesn't allow it.
639	*
640	* The calling function must still handle the error.
641	*/
642	static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
643	pte_t pte, struct page *page)
644	{
645	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
646	pud_t *pud = pud_offset(pgd, addr);
647	pmd_t *pmd = pmd_offset(pud, addr);
648	struct address_space *mapping;
649	pgoff_t index;
650	static unsigned long resume;
651	static unsigned long nr_shown;
652	static unsigned long nr_unshown;
653
654	/*
655	* Allow a burst of 60 reports, then keep quiet for that minute;
656	* or allow a steady drip of one report per second.
657	*/
658	if (nr_shown == 60) {
659	if (time_before(jiffies, resume)) {
660	nr_unshown++;
661	return;
662	}
663	if (nr_unshown) {
664	pr_alert("BUG: Bad page map: %lu messages suppressed\n",
665	nr_unshown);
666	nr_unshown = 0;
667	}
668	nr_shown = 0;
669	}
670	if (nr_shown++ == 0)
671	resume = jiffies + 60 * HZ;
672
673	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
674	index = linear_page_index(vma, addr);
675
676	pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
677	current->comm,
678	(long long)pte_val(pte), (long long)pmd_val(*pmd));
679	if (page)
680	dump_page(page, "bad pte");
681	pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
682	(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
683	/*
684	* Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
685	*/
686	pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
687	vma->vm_file,
688	vma->vm_ops ? vma->vm_ops->fault : NULL,
689	vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
690	mapping ? mapping->a_ops->readpage : NULL);
691	dump_stack();
692	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
693	}
694
695	/*
696	* vm_normal_page -- This function gets the "struct page" associated with a pte.
697	*
698	* "Special" mappings do not wish to be associated with a "struct page" (either
699	* it doesn't exist, or it exists but they don't want to touch it). In this
700	* case, NULL is returned here. "Normal" mappings do have a struct page.
701	*
702	* There are 2 broad cases. Firstly, an architecture may define a pte_special()
703	* pte bit, in which case this function is trivial. Secondly, an architecture
704	* may not have a spare pte bit, which requires a more complicated scheme,
705	* described below.
706	*
707	* A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
708	* special mapping (even if there are underlying and valid "struct pages").
709	* COWed pages of a VM_PFNMAP are always normal.
710	*
711	* The way we recognize COWed pages within VM_PFNMAP mappings is through the
712	* rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
713	* set, and the vm_pgoff will point to the first PFN mapped: thus every special
714	* mapping will always honor the rule
715	*
716	* pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
717	*
718	* And for normal mappings this is false.
719	*
720	* This restricts such mappings to be a linear translation from virtual address
721	* to pfn. To get around this restriction, we allow arbitrary mappings so long
722	* as the vma is not a COW mapping; in that case, we know that all ptes are
723	* special (because none can have been COWed).
724	*
725	*
726	* In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
727	*
728	* VM_MIXEDMAP mappings can likewise contain memory with or without "struct
729	* page" backing, however the difference is that _all_ pages with a struct
730	* page (that is, those where pfn_valid is true) are refcounted and considered
731	* normal pages by the VM. The disadvantage is that pages are refcounted
732	* (which can be slower and simply not an option for some PFNMAP users). The
733	* advantage is that we don't have to follow the strict linearity rule of
734	* PFNMAP mappings in order to support COWable mappings.
735	*
736	*/
737	#ifdef __HAVE_ARCH_PTE_SPECIAL
738	# define HAVE_PTE_SPECIAL 1
739	#else
740	# define HAVE_PTE_SPECIAL 0
741	#endif
742	struct page vm_normal_page(struct vm_area_struct vma, unsigned long addr,
743	pte_t pte)
744	{
745	unsigned long pfn = pte_pfn(pte);
746
747	if (HAVE_PTE_SPECIAL) {
748	if (likely(!pte_special(pte)))
749	goto check_pfn;
750	if (vma->vm_ops && vma->vm_ops->find_special_page)
751	return vma->vm_ops->find_special_page(vma, addr);
752	if (vma->vm_flags & (VM_PFNMAP \| VM_MIXEDMAP))
753	return NULL;
754	if (!is_zero_pfn(pfn))
755	print_bad_pte(vma, addr, pte, NULL);
756	return NULL;
757	}
758
759	/* !HAVE_PTE_SPECIAL case follows: */
760
761	if (unlikely(vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP))) {
762	if (vma->vm_flags & VM_MIXEDMAP) {
763	if (!pfn_valid(pfn))
764	return NULL;
765	goto out;
766	} else {
767	unsigned long off;
768	off = (addr - vma->vm_start) >> PAGE_SHIFT;
769	if (pfn == vma->vm_pgoff + off)
770	return NULL;
771	if (!is_cow_mapping(vma->vm_flags))
772	return NULL;
773	}
774	}
775
776	if (is_zero_pfn(pfn))
777	return NULL;
778	check_pfn:
779	if (unlikely(pfn > highest_memmap_pfn)) {
780	print_bad_pte(vma, addr, pte, NULL);
781	return NULL;
782	}
783
784	/*
785	* NOTE! We still have PageReserved() pages in the page tables.
786	* eg. VDSO mappings can cause them to exist.
787	*/
788	out:
789	return pfn_to_page(pfn);
790	}
791
792	#ifdef CONFIG_TRANSPARENT_HUGEPAGE
793	struct page vm_normal_page_pmd(struct vm_area_struct vma, unsigned long addr,
794	pmd_t pmd)
795	{
796	unsigned long pfn = pmd_pfn(pmd);
797
798	/*
799	* There is no pmd_special() but there may be special pmds, e.g.
800	* in a direct-access (dax) mapping, so let's just replicate the
801	* !HAVE_PTE_SPECIAL case from vm_normal_page() here.
802	*/
803	if (unlikely(vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP))) {
804	if (vma->vm_flags & VM_MIXEDMAP) {
805	if (!pfn_valid(pfn))
806	return NULL;
807	goto out;
808	} else {
809	unsigned long off;
810	off = (addr - vma->vm_start) >> PAGE_SHIFT;
811	if (pfn == vma->vm_pgoff + off)
812	return NULL;
813	if (!is_cow_mapping(vma->vm_flags))
814	return NULL;
815	}
816	}
817
818	if (is_zero_pfn(pfn))
819	return NULL;
820	if (unlikely(pfn > highest_memmap_pfn))
821	return NULL;
822
823	/*
824	* NOTE! We still have PageReserved() pages in the page tables.
825	* eg. VDSO mappings can cause them to exist.
826	*/
827	out:
828	return pfn_to_page(pfn);
829	}
830	#endif
831
832	/*
833	* copy one vm_area from one task to the other. Assumes the page tables
834	* already present in the new task to be cleared in the whole range
835	* covered by this vma.
836	*/
837
838	static inline unsigned long
839	copy_one_pte(struct mm_struct dst_mm, struct mm_struct src_mm,
840	pte_t dst_pte, pte_t src_pte, struct vm_area_struct *vma,
841	unsigned long addr, int *rss)
842	{
843	unsigned long vm_flags = vma->vm_flags;
844	pte_t pte = *src_pte;
845	struct page *page;
846
847	/* pte contains position in swap or file, so copy. */
848	if (unlikely(!pte_present(pte))) {
849	swp_entry_t entry = pte_to_swp_entry(pte);
850
851	if (likely(!non_swap_entry(entry))) {
852	if (swap_duplicate(entry) < 0)
853	return entry.val;
854
855	/* make sure dst_mm is on swapoff's mmlist. */
856	if (unlikely(list_empty(&dst_mm->mmlist))) {
857	spin_lock(&mmlist_lock);
858	if (list_empty(&dst_mm->mmlist))
859	list_add(&dst_mm->mmlist,
860	&src_mm->mmlist);
861	spin_unlock(&mmlist_lock);
862	}
863	rss[MM_SWAPENTS]++;
864	} else if (is_migration_entry(entry)) {
865	page = migration_entry_to_page(entry);
866
867	rss[mm_counter(page)]++;
868
869	if (is_write_migration_entry(entry) &&
870	is_cow_mapping(vm_flags)) {
871	/*
872	* COW mappings require pages in both
873	* parent and child to be set to read.
874	*/
875	make_migration_entry_read(&entry);
876	pte = swp_entry_to_pte(entry);
877	if (pte_swp_soft_dirty(*src_pte))
878	pte = pte_swp_mksoft_dirty(pte);
879	set_pte_at(src_mm, addr, src_pte, pte);
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, false);
906	rss[mm_counter(page)]++;
907	}
908
909	out_set_pte:
910	set_pte_at(dst_mm, addr, dst_pte, pte);
911	return 0;
912	}
913
914	static int copy_pte_range(struct mm_struct dst_mm, struct mm_struct src_mm,
915	pmd_t dst_pmd, pmd_t src_pmd, struct vm_area_struct *vma,
916	unsigned long addr, unsigned long end)
917	{
918	pte_t orig_src_pte, orig_dst_pte;
919	pte_t src_pte, dst_pte;
920	spinlock_t src_ptl, dst_ptl;
921	int progress = 0;
922	int rss[NR_MM_COUNTERS];
923	swp_entry_t entry = (swp_entry_t){0};
924
925	again:
926	init_rss_vec(rss);
927
928	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
929	if (!dst_pte)
930	return -ENOMEM;
931	src_pte = pte_offset_map(src_pmd, addr);
932	src_ptl = pte_lockptr(src_mm, src_pmd);
933	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
934	orig_src_pte = src_pte;
935	orig_dst_pte = dst_pte;
936	arch_enter_lazy_mmu_mode();
937
938	do {
939	/*
940	* We are holding two locks at this point - either of them
941	* could generate latencies in another task on another CPU.
942	*/
943	if (progress >= 32) {
944	progress = 0;
945	if (need_resched() \|\|
946	spin_needbreak(src_ptl) \|\| spin_needbreak(dst_ptl))
947	break;
948	}
949	if (pte_none(*src_pte)) {
950	progress++;
951	continue;
952	}
953	entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
954	vma, addr, rss);
955	if (entry.val)
956	break;
957	progress += 8;
958	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
959
960	arch_leave_lazy_mmu_mode();
961	spin_unlock(src_ptl);
962	pte_unmap(orig_src_pte);
963	add_mm_rss_vec(dst_mm, rss);
964	pte_unmap_unlock(orig_dst_pte, dst_ptl);
965	cond_resched();
966
967	if (entry.val) {
968	if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
969	return -ENOMEM;
970	progress = 0;
971	}
972	if (addr != end)
973	goto again;
974	return 0;
975	}
976
977	static inline int copy_pmd_range(struct mm_struct dst_mm, struct mm_struct src_mm,
978	pud_t dst_pud, pud_t src_pud, struct vm_area_struct *vma,
979	unsigned long addr, unsigned long end)
980	{
981	pmd_t src_pmd, dst_pmd;
982	unsigned long next;
983
984	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
985	if (!dst_pmd)
986	return -ENOMEM;
987	src_pmd = pmd_offset(src_pud, addr);
988	do {
989	next = pmd_addr_end(addr, end);
990	if (pmd_trans_huge(src_pmd) \|\| pmd_devmap(src_pmd)) {
991	int err;
992	VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
993	err = copy_huge_pmd(dst_mm, src_mm,
994	dst_pmd, src_pmd, addr, vma);
995	if (err == -ENOMEM)
996	return -ENOMEM;
997	if (!err)
998	continue;
999	/* fall through */
1000	}
1001	if (pmd_none_or_clear_bad(src_pmd))
1002	continue;
1003	if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1004	vma, addr, next))
1005	return -ENOMEM;
1006	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
1007	return 0;
1008	}
1009
1010	static inline int copy_pud_range(struct mm_struct dst_mm, struct mm_struct src_mm,
1011	pgd_t dst_pgd, pgd_t src_pgd, struct vm_area_struct *vma,
1012	unsigned long addr, unsigned long end)
1013	{
1014	pud_t src_pud, dst_pud;
1015	unsigned long next;
1016
1017	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1018	if (!dst_pud)
1019	return -ENOMEM;
1020	src_pud = pud_offset(src_pgd, addr);
1021	do {
1022	next = pud_addr_end(addr, end);
1023	if (pud_none_or_clear_bad(src_pud))
1024	continue;
1025	if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1026	vma, addr, next))
1027	return -ENOMEM;
1028	} while (dst_pud++, src_pud++, addr = next, addr != end);
1029	return 0;
1030	}
1031
1032	int copy_page_range(struct mm_struct dst_mm, struct mm_struct src_mm,
1033	struct vm_area_struct *vma)
1034	{
1035	pgd_t src_pgd, dst_pgd;
1036	unsigned long next;
1037	unsigned long addr = vma->vm_start;
1038	unsigned long end = vma->vm_end;
1039	unsigned long mmun_start; /* For mmu_notifiers */
1040	unsigned long mmun_end; /* For mmu_notifiers */
1041	bool is_cow;
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_PFNMAP \| VM_MIXEDMAP)) &&
1051	!vma->anon_vma)
1052	return 0;
1053
1054	if (is_vm_hugetlb_page(vma))
1055	return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1056
1057	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1058	/*
1059	* We do not free on error cases below as remove_vma
1060	* gets called on error from higher level routine
1061	*/
1062	ret = track_pfn_copy(vma);
1063	if (ret)
1064	return ret;
1065	}
1066
1067	/*
1068	* We need to invalidate the secondary MMU mappings only when
1069	* there could be a permission downgrade on the ptes of the
1070	* parent mm. And a permission downgrade will only happen if
1071	* is_cow_mapping() returns true.
1072	*/
1073	is_cow = is_cow_mapping(vma->vm_flags);
1074	mmun_start = addr;
1075	mmun_end = end;
1076	if (is_cow)
1077	mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1078	mmun_end);
1079
1080	ret = 0;
1081	dst_pgd = pgd_offset(dst_mm, addr);
1082	src_pgd = pgd_offset(src_mm, addr);
1083	do {
1084	next = pgd_addr_end(addr, end);
1085	if (pgd_none_or_clear_bad(src_pgd))
1086	continue;
1087	if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1088	vma, addr, next))) {
1089	ret = -ENOMEM;
1090	break;
1091	}
1092	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
1093
1094	if (is_cow)
1095	mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1096	return ret;
1097	}
1098
1099	static unsigned long zap_pte_range(struct mmu_gather *tlb,
1100	struct vm_area_struct vma, pmd_t pmd,
1101	unsigned long addr, unsigned long end,
1102	struct zap_details *details)
1103	{
1104	struct mm_struct *mm = tlb->mm;
1105	int force_flush = 0;
1106	int rss[NR_MM_COUNTERS];
1107	spinlock_t *ptl;
1108	pte_t *start_pte;
1109	pte_t *pte;
1110	swp_entry_t entry;
1111
1112	again:
1113	init_rss_vec(rss);
1114	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1115	pte = start_pte;
1116	arch_enter_lazy_mmu_mode();
1117	do {
1118	pte_t ptent = *pte;
1119	if (pte_none(ptent)) {
1120	continue;
1121	}
1122
1123	if (pte_present(ptent)) {
1124	struct page *page;
1125
1126	page = vm_normal_page(vma, addr, ptent);
1127	if (unlikely(details) && page) {
1128	/*
1129	* unmap_shared_mapping_pages() wants to
1130	* invalidate cache without truncating:
1131	* unmap shared but keep private pages.
1132	*/
1133	if (details->check_mapping &&
1134	details->check_mapping != page->mapping)
1135	continue;
1136	}
1137	ptent = ptep_get_and_clear_full(mm, addr, pte,
1138	tlb->fullmm);
1139	tlb_remove_tlb_entry(tlb, pte, addr);
1140	if (unlikely(!page))
1141	continue;
1142
1143	if (!PageAnon(page)) {
1144	if (pte_dirty(ptent)) {
1145	/*
1146	* oom_reaper cannot tear down dirty
1147	* pages
1148	*/
1149	if (unlikely(details && details->ignore_dirty))
1150	continue;
1151	force_flush = 1;
1152	set_page_dirty(page);
1153	}
1154	if (pte_young(ptent) &&
1155	likely(!(vma->vm_flags & VM_SEQ_READ)))
1156	mark_page_accessed(page);
1157	}
1158	rss[mm_counter(page)]--;
1159	page_remove_rmap(page, false);
1160	if (unlikely(page_mapcount(page) < 0))
1161	print_bad_pte(vma, addr, ptent, page);
1162	if (unlikely(!__tlb_remove_page(tlb, page))) {
1163	force_flush = 1;
1164	addr += PAGE_SIZE;
1165	break;
1166	}
1167	continue;
1168	}
1169	/* only check swap_entries if explicitly asked for in details */
1170	if (unlikely(details && !details->check_swap_entries))
1171	continue;
1172
1173	entry = pte_to_swp_entry(ptent);
1174	if (!non_swap_entry(entry))
1175	rss[MM_SWAPENTS]--;
1176	else if (is_migration_entry(entry)) {
1177	struct page *page;
1178
1179	page = migration_entry_to_page(entry);
1180	rss[mm_counter(page)]--;
1181	}
1182	if (unlikely(!free_swap_and_cache(entry)))
1183	print_bad_pte(vma, addr, ptent, NULL);
1184	pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1185	} while (pte++, addr += PAGE_SIZE, addr != end);
1186
1187	add_mm_rss_vec(mm, rss);
1188	arch_leave_lazy_mmu_mode();
1189
1190	/* Do the actual TLB flush before dropping ptl */
1191	if (force_flush)
1192	tlb_flush_mmu_tlbonly(tlb);
1193	pte_unmap_unlock(start_pte, ptl);
1194
1195	/*
1196	* If we forced a TLB flush (either due to running out of
1197	* batch buffers or because we needed to flush dirty TLB
1198	* entries before releasing the ptl), free the batched
1199	* memory too. Restart if we didn't do everything.
1200	*/
1201	if (force_flush) {
1202	force_flush = 0;
1203	tlb_flush_mmu_free(tlb);
1204
1205	if (addr != end)
1206	goto again;
1207	}
1208
1209	return addr;
1210	}
1211
1212	static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1213	struct vm_area_struct vma, pud_t pud,
1214	unsigned long addr, unsigned long end,
1215	struct zap_details *details)
1216	{
1217	pmd_t *pmd;
1218	unsigned long next;
1219
1220	pmd = pmd_offset(pud, addr);
1221	do {
1222	next = pmd_addr_end(addr, end);
1223	if (pmd_trans_huge(pmd) \|\| pmd_devmap(pmd)) {
1224	if (next - addr != HPAGE_PMD_SIZE) {
1225	VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
1226	!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1227	split_huge_pmd(vma, pmd, addr);
1228	} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1229	goto next;
1230	/* fall through */
1231	}
1232	/*
1233	* Here there can be other concurrent MADV_DONTNEED or
1234	* trans huge page faults running, and if the pmd is
1235	* none or trans huge it can change under us. This is
1236	* because MADV_DONTNEED holds the mmap_sem in read
1237	* mode.
1238	*/
1239	if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1240	goto next;
1241	next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1242	next:
1243	cond_resched();
1244	} while (pmd++, addr = next, addr != end);
1245
1246	return addr;
1247	}
1248
1249	static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1250	struct vm_area_struct vma, pgd_t pgd,
1251	unsigned long addr, unsigned long end,
1252	struct zap_details *details)
1253	{
1254	pud_t *pud;
1255	unsigned long next;
1256
1257	pud = pud_offset(pgd, addr);
1258	do {
1259	next = pud_addr_end(addr, end);
1260	if (pud_none_or_clear_bad(pud))
1261	continue;
1262	next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1263	} while (pud++, addr = next, addr != end);
1264
1265	return addr;
1266	}
1267
1268	void unmap_page_range(struct mmu_gather *tlb,
1269	struct vm_area_struct *vma,
1270	unsigned long addr, unsigned long end,
1271	struct zap_details *details)
1272	{
1273	pgd_t *pgd;
1274	unsigned long next;
1275
1276	BUG_ON(addr >= end);
1277	tlb_start_vma(tlb, vma);
1278	pgd = pgd_offset(vma->vm_mm, addr);
1279	do {
1280	next = pgd_addr_end(addr, end);
1281	if (pgd_none_or_clear_bad(pgd))
1282	continue;
1283	next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1284	} while (pgd++, addr = next, addr != end);
1285	tlb_end_vma(tlb, vma);
1286	}
1287
1288
1289	static void unmap_single_vma(struct mmu_gather *tlb,
1290	struct vm_area_struct *vma, unsigned long start_addr,
1291	unsigned long end_addr,
1292	struct zap_details *details)
1293	{
1294	unsigned long start = max(vma->vm_start, start_addr);
1295	unsigned long end;
1296
1297	if (start >= vma->vm_end)
1298	return;
1299	end = min(vma->vm_end, end_addr);
1300	if (end <= vma->vm_start)
1301	return;
1302
1303	if (vma->vm_file)
1304	uprobe_munmap(vma, start, end);
1305
1306	if (unlikely(vma->vm_flags & VM_PFNMAP))
1307	untrack_pfn(vma, 0, 0);
1308
1309	if (start != end) {
1310	if (unlikely(is_vm_hugetlb_page(vma))) {
1311	/*
1312	* It is undesirable to test vma->vm_file as it
1313	* should be non-null for valid hugetlb area.
1314	* However, vm_file will be NULL in the error
1315	* cleanup path of mmap_region. When
1316	* hugetlbfs ->mmap method fails,
1317	* mmap_region() nullifies vma->vm_file
1318	* before calling this function to clean up.
1319	* Since no pte has actually been setup, it is
1320	* safe to do nothing in this case.
1321	*/
1322	if (vma->vm_file) {
1323	i_mmap_lock_write(vma->vm_file->f_mapping);
1324	__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1325	i_mmap_unlock_write(vma->vm_file->f_mapping);
1326	}
1327	} else
1328	unmap_page_range(tlb, vma, start, end, details);
1329	}
1330	}
1331
1332	/**
1333	* unmap_vmas - unmap a range of memory covered by a list of vma's
1334	* @tlb: address of the caller's struct mmu_gather
1335	* @vma: the starting vma
1336	* @start_addr: virtual address at which to start unmapping
1337	* @end_addr: virtual address at which to end unmapping
1338	*
1339	* Unmap all pages in the vma list.
1340	*
1341	* Only addresses between `start' and `end' will be unmapped.
1342	*
1343	* The VMA list must be sorted in ascending virtual address order.
1344	*
1345	* unmap_vmas() assumes that the caller will flush the whole unmapped address
1346	* range after unmap_vmas() returns. So the only responsibility here is to
1347	* ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1348	* drops the lock and schedules.
1349	*/
1350	void unmap_vmas(struct mmu_gather *tlb,
1351	struct vm_area_struct *vma, unsigned long start_addr,
1352	unsigned long end_addr)
1353	{
1354	struct mm_struct *mm = vma->vm_mm;
1355
1356	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1357	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1358	unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1359	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1360	}
1361
1362	/**
1363	* zap_page_range - remove user pages in a given range
1364	* @vma: vm_area_struct holding the applicable pages
1365	* @start: starting address of pages to zap
1366	* @size: number of bytes to zap
1367	* @details: details of shared cache invalidation
1368	*
1369	* Caller must protect the VMA list
1370	*/
1371	void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1372	unsigned long size, struct zap_details *details)
1373	{
1374	struct mm_struct *mm = vma->vm_mm;
1375	struct mmu_gather tlb;
1376	unsigned long end = start + size;
1377
1378	lru_add_drain();
1379	tlb_gather_mmu(&tlb, mm, start, end);
1380	update_hiwater_rss(mm);
1381	mmu_notifier_invalidate_range_start(mm, start, end);
1382	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1383	unmap_single_vma(&tlb, vma, start, end, details);
1384	mmu_notifier_invalidate_range_end(mm, start, end);
1385	tlb_finish_mmu(&tlb, start, end);
1386	}
1387
1388	/**
1389	* zap_page_range_single - remove user pages in a given range
1390	* @vma: vm_area_struct holding the applicable pages
1391	* @address: starting address of pages to zap
1392	* @size: number of bytes to zap
1393	* @details: details of shared cache invalidation
1394	*
1395	* The range must fit into one VMA.
1396	*/
1397	static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1398	unsigned long size, struct zap_details *details)
1399	{
1400	struct mm_struct *mm = vma->vm_mm;
1401	struct mmu_gather tlb;
1402	unsigned long end = address + size;
1403
1404	lru_add_drain();
1405	tlb_gather_mmu(&tlb, mm, address, end);
1406	update_hiwater_rss(mm);
1407	mmu_notifier_invalidate_range_start(mm, address, end);
1408	unmap_single_vma(&tlb, vma, address, end, details);
1409	mmu_notifier_invalidate_range_end(mm, address, end);
1410	tlb_finish_mmu(&tlb, address, end);
1411	}
1412
1413	/**
1414	* zap_vma_ptes - remove ptes mapping the vma
1415	* @vma: vm_area_struct holding ptes to be zapped
1416	* @address: starting address of pages to zap
1417	* @size: number of bytes to zap
1418	*
1419	* This function only unmaps ptes assigned to VM_PFNMAP vmas.
1420	*
1421	* The entire address range must be fully contained within the vma.
1422	*
1423	* Returns 0 if successful.
1424	*/
1425	int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1426	unsigned long size)
1427	{
1428	if (address < vma->vm_start \|\| address + size > vma->vm_end \|\|
1429	!(vma->vm_flags & VM_PFNMAP))
1430	return -1;
1431	zap_page_range_single(vma, address, size, NULL);
1432	return 0;
1433	}
1434	EXPORT_SYMBOL_GPL(zap_vma_ptes);
1435
1436	pte_t __get_locked_pte(struct mm_struct mm, unsigned long addr,
1437	spinlock_t **ptl)
1438	{
1439	pgd_t * pgd = pgd_offset(mm, addr);
1440	pud_t * pud = pud_alloc(mm, pgd, addr);
1441	if (pud) {
1442	pmd_t * pmd = pmd_alloc(mm, pud, addr);
1443	if (pmd) {
1444	VM_BUG_ON(pmd_trans_huge(*pmd));
1445	return pte_alloc_map_lock(mm, pmd, addr, ptl);
1446	}
1447	}
1448	return NULL;
1449	}
1450
1451	/*
1452	* This is the old fallback for page remapping.
1453	*
1454	* For historical reasons, it only allows reserved pages. Only
1455	* old drivers should use this, and they needed to mark their
1456	* pages reserved for the old functions anyway.
1457	*/
1458	static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1459	struct page *page, pgprot_t prot)
1460	{
1461	struct mm_struct *mm = vma->vm_mm;
1462	int retval;
1463	pte_t *pte;
1464	spinlock_t *ptl;
1465
1466	retval = -EINVAL;
1467	if (PageAnon(page))
1468	goto out;
1469	retval = -ENOMEM;
1470	flush_dcache_page(page);
1471	pte = get_locked_pte(mm, addr, &ptl);
1472	if (!pte)
1473	goto out;
1474	retval = -EBUSY;
1475	if (!pte_none(*pte))
1476	goto out_unlock;
1477
1478	/* Ok, finally just insert the thing.. */
1479	get_page(page);
1480	inc_mm_counter_fast(mm, mm_counter_file(page));
1481	page_add_file_rmap(page);
1482	set_pte_at(mm, addr, pte, mk_pte(page, prot));
1483
1484	retval = 0;
1485	pte_unmap_unlock(pte, ptl);
1486	return retval;
1487	out_unlock:
1488	pte_unmap_unlock(pte, ptl);
1489	out:
1490	return retval;
1491	}
1492
1493	/**
1494	* vm_insert_page - insert single page into user vma
1495	* @vma: user vma to map to
1496	* @addr: target user address of this page
1497	* @page: source kernel page
1498	*
1499	* This allows drivers to insert individual pages they've allocated
1500	* into a user vma.
1501	*
1502	* The page has to be a nice clean _individual_ kernel allocation.
1503	* If you allocate a compound page, you need to have marked it as
1504	* such (__GFP_COMP), or manually just split the page up yourself
1505	* (see split_page()).
1506	*
1507	* NOTE! Traditionally this was done with "remap_pfn_range()" which
1508	* took an arbitrary page protection parameter. This doesn't allow
1509	* that. Your vma protection will have to be set up correctly, which
1510	* means that if you want a shared writable mapping, you'd better
1511	* ask for a shared writable mapping!
1512	*
1513	* The page does not need to be reserved.
1514	*
1515	* Usually this function is called from f_op->mmap() handler
1516	* under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1517	* Caller must set VM_MIXEDMAP on vma if it wants to call this
1518	* function from other places, for example from page-fault handler.
1519	*/
1520	int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1521	struct page *page)
1522	{
1523	if (addr < vma->vm_start \|\| addr >= vma->vm_end)
1524	return -EFAULT;
1525	if (!page_count(page))
1526	return -EINVAL;
1527	if (!(vma->vm_flags & VM_MIXEDMAP)) {
1528	BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1529	BUG_ON(vma->vm_flags & VM_PFNMAP);
1530	vma->vm_flags \|= VM_MIXEDMAP;
1531	}
1532	return insert_page(vma, addr, page, vma->vm_page_prot);
1533	}
1534	EXPORT_SYMBOL(vm_insert_page);
1535
1536	static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1537	pfn_t pfn, pgprot_t prot)
1538	{
1539	struct mm_struct *mm = vma->vm_mm;
1540	int retval;
1541	pte_t *pte, entry;
1542	spinlock_t *ptl;
1543
1544	retval = -ENOMEM;
1545	pte = get_locked_pte(mm, addr, &ptl);
1546	if (!pte)
1547	goto out;
1548	retval = -EBUSY;
1549	if (!pte_none(*pte))
1550	goto out_unlock;
1551
1552	/* Ok, finally just insert the thing.. */
1553	if (pfn_t_devmap(pfn))
1554	entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1555	else
1556	entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1557	set_pte_at(mm, addr, pte, entry);
1558	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1559
1560	retval = 0;
1561	out_unlock:
1562	pte_unmap_unlock(pte, ptl);
1563	out:
1564	return retval;
1565	}
1566
1567	/**
1568	* vm_insert_pfn - insert single pfn into user vma
1569	* @vma: user vma to map to
1570	* @addr: target user address of this page
1571	* @pfn: source kernel pfn
1572	*
1573	* Similar to vm_insert_page, this allows drivers to insert individual pages
1574	* they've allocated into a user vma. Same comments apply.
1575	*
1576	* This function should only be called from a vm_ops->fault handler, and
1577	* in that case the handler should return NULL.
1578	*
1579	* vma cannot be a COW mapping.
1580	*
1581	* As this is called only for pages that do not currently exist, we
1582	* do not need to flush old virtual caches or the TLB.
1583	*/
1584	int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1585	unsigned long pfn)
1586	{
1587	return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1588	}
1589	EXPORT_SYMBOL(vm_insert_pfn);
1590
1591	/**
1592	* vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1593	* @vma: user vma to map to
1594	* @addr: target user address of this page
1595	* @pfn: source kernel pfn
1596	* @pgprot: pgprot flags for the inserted page
1597	*
1598	* This is exactly like vm_insert_pfn, except that it allows drivers to
1599	* to override pgprot on a per-page basis.
1600	*
1601	* This only makes sense for IO mappings, and it makes no sense for
1602	* cow mappings. In general, using multiple vmas is preferable;
1603	* vm_insert_pfn_prot should only be used if using multiple VMAs is
1604	* impractical.
1605	*/
1606	int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1607	unsigned long pfn, pgprot_t pgprot)
1608	{
1609	int ret;
1610	/*
1611	* Technically, architectures with pte_special can avoid all these
1612	* restrictions (same for remap_pfn_range). However we would like
1613	* consistency in testing and feature parity among all, so we should
1614	* try to keep these invariants in place for everybody.
1615	*/
1616	BUG_ON(!(vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP)));
1617	BUG_ON((vma->vm_flags & (VM_PFNMAP\|VM_MIXEDMAP)) ==
1618	(VM_PFNMAP\|VM_MIXEDMAP));
1619	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1620	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1621
1622	if (addr < vma->vm_start \|\| addr >= vma->vm_end)
1623	return -EFAULT;
1624	if (track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)))
1625	return -EINVAL;
1626
1627	ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
1628
1629	return ret;
1630	}
1631	EXPORT_SYMBOL(vm_insert_pfn_prot);
1632
1633	int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1634	pfn_t pfn)
1635	{
1636	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1637
1638	if (addr < vma->vm_start \|\| addr >= vma->vm_end)
1639	return -EFAULT;
1640
1641	/*
1642	* If we don't have pte special, then we have to use the pfn_valid()
1643	* based VM_MIXEDMAP scheme (see vm_normal_page), and thus we must
1644	* refcount the page if pfn_valid is true (hence insert_page rather
1645	* than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1646	* without pte special, it would there be refcounted as a normal page.
1647	*/
1648	if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1649	struct page *page;
1650
1651	/*
1652	* At this point we are committed to insert_page()
1653	* regardless of whether the caller specified flags that
1654	* result in pfn_t_has_page() == false.
1655	*/
1656	page = pfn_to_page(pfn_t_to_pfn(pfn));
1657	return insert_page(vma, addr, page, vma->vm_page_prot);
1658	}
1659	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1660	}
1661	EXPORT_SYMBOL(vm_insert_mixed);
1662
1663	/*
1664	* maps a range of physical memory into the requested pages. the old
1665	* mappings are removed. any references to nonexistent pages results
1666	* in null mappings (currently treated as "copy-on-access")
1667	*/
1668	static int remap_pte_range(struct mm_struct mm, pmd_t pmd,
1669	unsigned long addr, unsigned long end,
1670	unsigned long pfn, pgprot_t prot)
1671	{
1672	pte_t *pte;
1673	spinlock_t *ptl;
1674
1675	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1676	if (!pte)
1677	return -ENOMEM;
1678	arch_enter_lazy_mmu_mode();
1679	do {
1680	BUG_ON(!pte_none(*pte));
1681	set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1682	pfn++;
1683	} while (pte++, addr += PAGE_SIZE, addr != end);
1684	arch_leave_lazy_mmu_mode();
1685	pte_unmap_unlock(pte - 1, ptl);
1686	return 0;
1687	}
1688
1689	static inline int remap_pmd_range(struct mm_struct mm, pud_t pud,
1690	unsigned long addr, unsigned long end,
1691	unsigned long pfn, pgprot_t prot)
1692	{
1693	pmd_t *pmd;
1694	unsigned long next;
1695
1696	pfn -= addr >> PAGE_SHIFT;
1697	pmd = pmd_alloc(mm, pud, addr);
1698	if (!pmd)
1699	return -ENOMEM;
1700	VM_BUG_ON(pmd_trans_huge(*pmd));
1701	do {
1702	next = pmd_addr_end(addr, end);
1703	if (remap_pte_range(mm, pmd, addr, next,
1704	pfn + (addr >> PAGE_SHIFT), prot))
1705	return -ENOMEM;
1706	} while (pmd++, addr = next, addr != end);
1707	return 0;
1708	}
1709
1710	static inline int remap_pud_range(struct mm_struct mm, pgd_t pgd,
1711	unsigned long addr, unsigned long end,
1712	unsigned long pfn, pgprot_t prot)
1713	{
1714	pud_t *pud;
1715	unsigned long next;
1716
1717	pfn -= addr >> PAGE_SHIFT;
1718	pud = pud_alloc(mm, pgd, addr);
1719	if (!pud)
1720	return -ENOMEM;
1721	do {
1722	next = pud_addr_end(addr, end);
1723	if (remap_pmd_range(mm, pud, addr, next,
1724	pfn + (addr >> PAGE_SHIFT), prot))
1725	return -ENOMEM;
1726	} while (pud++, addr = next, addr != end);
1727	return 0;
1728	}
1729
1730	/**
1731	* remap_pfn_range - remap kernel memory to userspace
1732	* @vma: user vma to map to
1733	* @addr: target user address to start at
1734	* @pfn: physical address of kernel memory
1735	* @size: size of map area
1736	* @prot: page protection flags for this mapping
1737	*
1738	* Note: this is only safe if the mm semaphore is held when called.
1739	*/
1740	int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1741	unsigned long pfn, unsigned long size, pgprot_t prot)
1742	{
1743	pgd_t *pgd;
1744	unsigned long next;
1745	unsigned long end = addr + PAGE_ALIGN(size);
1746	struct mm_struct *mm = vma->vm_mm;
1747	int err;
1748
1749	/*
1750	* Physically remapped pages are special. Tell the
1751	* rest of the world about it:
1752	* VM_IO tells people not to look at these pages
1753	* (accesses can have side effects).
1754	* VM_PFNMAP tells the core MM that the base pages are just
1755	* raw PFN mappings, and do not have a "struct page" associated
1756	* with them.
1757	* VM_DONTEXPAND
1758	* Disable vma merging and expanding with mremap().
1759	* VM_DONTDUMP
1760	* Omit vma from core dump, even when VM_IO turned off.
1761	*
1762	* There's a horrible special case to handle copy-on-write
1763	* behaviour that some programs depend on. We mark the "original"
1764	* un-COW'ed pages by matching them up with "vma->vm_pgoff".
1765	* See vm_normal_page() for details.
1766	*/
1767	if (is_cow_mapping(vma->vm_flags)) {
1768	if (addr != vma->vm_start \|\| end != vma->vm_end)
1769	return -EINVAL;
1770	vma->vm_pgoff = pfn;
1771	}
1772
1773	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
1774	if (err)
1775	return -EINVAL;
1776
1777	vma->vm_flags \|= VM_IO \| VM_PFNMAP \| VM_DONTEXPAND \| VM_DONTDUMP;
1778
1779	BUG_ON(addr >= end);
1780	pfn -= addr >> PAGE_SHIFT;
1781	pgd = pgd_offset(mm, addr);
1782	flush_cache_range(vma, addr, end);
1783	do {
1784	next = pgd_addr_end(addr, end);
1785	err = remap_pud_range(mm, pgd, addr, next,
1786	pfn + (addr >> PAGE_SHIFT), prot);
1787	if (err)
1788	break;
1789	} while (pgd++, addr = next, addr != end);
1790
1791	if (err)
1792	untrack_pfn(vma, pfn, PAGE_ALIGN(size));
1793
1794	return err;
1795	}
1796	EXPORT_SYMBOL(remap_pfn_range);
1797
1798	/**
1799	* vm_iomap_memory - remap memory to userspace
1800	* @vma: user vma to map to
1801	* @start: start of area
1802	* @len: size of area
1803	*
1804	* This is a simplified io_remap_pfn_range() for common driver use. The
1805	* driver just needs to give us the physical memory range to be mapped,
1806	* we'll figure out the rest from the vma information.
1807	*
1808	* NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1809	* whatever write-combining details or similar.
1810	*/
1811	int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1812	{
1813	unsigned long vm_len, pfn, pages;
1814
1815	/* Check that the physical memory area passed in looks valid */
1816	if (start + len < start)
1817	return -EINVAL;
1818	/*
1819	* You really shouldn't map things that aren't page-aligned,
1820	* but we've historically allowed it because IO memory might
1821	* just have smaller alignment.
1822	*/
1823	len += start & ~PAGE_MASK;
1824	pfn = start >> PAGE_SHIFT;
1825	pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1826	if (pfn + pages < pfn)
1827	return -EINVAL;
1828
1829	/* We start the mapping 'vm_pgoff' pages into the area */
1830	if (vma->vm_pgoff > pages)
1831	return -EINVAL;
1832	pfn += vma->vm_pgoff;
1833	pages -= vma->vm_pgoff;
1834
1835	/* Can we fit all of the mapping? */
1836	vm_len = vma->vm_end - vma->vm_start;
1837	if (vm_len >> PAGE_SHIFT > pages)
1838	return -EINVAL;
1839
1840	/* Ok, let it rip */
1841	return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1842	}
1843	EXPORT_SYMBOL(vm_iomap_memory);
1844
1845	static int apply_to_pte_range(struct mm_struct mm, pmd_t pmd,
1846	unsigned long addr, unsigned long end,
1847	pte_fn_t fn, void *data)
1848	{
1849	pte_t *pte;
1850	int err;
1851	pgtable_t token;
1852	spinlock_t *uninitialized_var(ptl);
1853
1854	pte = (mm == &init_mm) ?
1855	pte_alloc_kernel(pmd, addr) :
1856	pte_alloc_map_lock(mm, pmd, addr, &ptl);
1857	if (!pte)
1858	return -ENOMEM;
1859
1860	BUG_ON(pmd_huge(*pmd));
1861
1862	arch_enter_lazy_mmu_mode();
1863
1864	token = pmd_pgtable(*pmd);
1865
1866	do {
1867	err = fn(pte++, token, addr, data);
1868	if (err)
1869	break;
1870	} while (addr += PAGE_SIZE, addr != end);
1871
1872	arch_leave_lazy_mmu_mode();
1873
1874	if (mm != &init_mm)
1875	pte_unmap_unlock(pte-1, ptl);
1876	return err;
1877	}
1878
1879	static int apply_to_pmd_range(struct mm_struct mm, pud_t pud,
1880	unsigned long addr, unsigned long end,
1881	pte_fn_t fn, void *data)
1882	{
1883	pmd_t *pmd;
1884	unsigned long next;
1885	int err;
1886
1887	BUG_ON(pud_huge(*pud));
1888
1889	pmd = pmd_alloc(mm, pud, addr);
1890	if (!pmd)
1891	return -ENOMEM;
1892	do {
1893	next = pmd_addr_end(addr, end);
1894	err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1895	if (err)
1896	break;
1897	} while (pmd++, addr = next, addr != end);
1898	return err;
1899	}
1900
1901	static int apply_to_pud_range(struct mm_struct mm, pgd_t pgd,
1902	unsigned long addr, unsigned long end,
1903	pte_fn_t fn, void *data)
1904	{
1905	pud_t *pud;
1906	unsigned long next;
1907	int err;
1908
1909	pud = pud_alloc(mm, pgd, addr);
1910	if (!pud)
1911	return -ENOMEM;
1912	do {
1913	next = pud_addr_end(addr, end);
1914	err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1915	if (err)
1916	break;
1917	} while (pud++, addr = next, addr != end);
1918	return err;
1919	}
1920
1921	/*
1922	* Scan a region of virtual memory, filling in page tables as necessary
1923	* and calling a provided function on each leaf page table.
1924	*/
1925	int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1926	unsigned long size, pte_fn_t fn, void *data)
1927	{
1928	pgd_t *pgd;
1929	unsigned long next;
1930	unsigned long end = addr + size;
1931	int err;
1932
1933	if (WARN_ON(addr >= end))
1934	return -EINVAL;
1935
1936	pgd = pgd_offset(mm, addr);
1937	do {
1938	next = pgd_addr_end(addr, end);
1939	err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1940	if (err)
1941	break;
1942	} while (pgd++, addr = next, addr != end);
1943
1944	return err;
1945	}
1946	EXPORT_SYMBOL_GPL(apply_to_page_range);
1947
1948	/*
1949	* handle_pte_fault chooses page fault handler according to an entry which was
1950	* read non-atomically. Before making any commitment, on those architectures
1951	* or configurations (e.g. i386 with PAE) which might give a mix of unmatched
1952	* parts, do_swap_page must check under lock before unmapping the pte and
1953	* proceeding (but do_wp_page is only called after already making such a check;
1954	* and do_anonymous_page can safely check later on).
1955	*/
1956	static inline int pte_unmap_same(struct mm_struct mm, pmd_t pmd,
1957	pte_t *page_table, pte_t orig_pte)
1958	{
1959	int same = 1;
1960	#if defined(CONFIG_SMP) \|\| defined(CONFIG_PREEMPT)
1961	if (sizeof(pte_t) > sizeof(unsigned long)) {
1962	spinlock_t *ptl = pte_lockptr(mm, pmd);
1963	spin_lock(ptl);
1964	same = pte_same(*page_table, orig_pte);
1965	spin_unlock(ptl);
1966	}
1967	#endif
1968	pte_unmap(page_table);
1969	return same;
1970	}
1971
1972	static inline void cow_user_page(struct page dst, struct page src, unsigned long va, struct vm_area_struct *vma)
1973	{
1974	debug_dma_assert_idle(src);
1975
1976	/*
1977	* If the source page was a PFN mapping, we don't have
1978	* a "struct page" for it. We do a best-effort copy by
1979	* just copying from the original user address. If that
1980	* fails, we just zero-fill it. Live with it.
1981	*/
1982	if (unlikely(!src)) {
1983	void *kaddr = kmap_atomic(dst);
1984	void __user uaddr = (void __user )(va & PAGE_MASK);
1985
1986	/*
1987	* This really shouldn't fail, because the page is there
1988	* in the page tables. But it might just be unreadable,
1989	* in which case we just give up and fill the result with
1990	* zeroes.
1991	*/
1992	if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1993	clear_page(kaddr);
1994	kunmap_atomic(kaddr);
1995	flush_dcache_page(dst);
1996	} else
1997	copy_user_highpage(dst, src, va, vma);
1998	}
1999
2000	static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2001	{
2002	struct file *vm_file = vma->vm_file;
2003
2004	if (vm_file)
2005	return mapping_gfp_mask(vm_file->f_mapping) \| __GFP_FS \| __GFP_IO;
2006
2007	/*
2008	* Special mappings (e.g. VDSO) do not have any file so fake
2009	* a default GFP_KERNEL for them.
2010	*/
2011	return GFP_KERNEL;
2012	}
2013
2014	/*
2015	* Notify the address space that the page is about to become writable so that
2016	* it can prohibit this or wait for the page to get into an appropriate state.
2017	*
2018	* We do this without the lock held, so that it can sleep if it needs to.
2019	*/
2020	static int do_page_mkwrite(struct vm_area_struct vma, struct page page,
2021	unsigned long address)
2022	{
2023	struct vm_fault vmf;
2024	int ret;
2025
2026	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2027	vmf.pgoff = page->index;
2028	vmf.flags = FAULT_FLAG_WRITE\|FAULT_FLAG_MKWRITE;
2029	vmf.gfp_mask = __get_fault_gfp_mask(vma);
2030	vmf.page = page;
2031	vmf.cow_page = NULL;
2032
2033	ret = vma->vm_ops->page_mkwrite(vma, &vmf);
2034	if (unlikely(ret & (VM_FAULT_ERROR \| VM_FAULT_NOPAGE)))
2035	return ret;
2036	if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2037	lock_page(page);
2038	if (!page->mapping) {
2039	unlock_page(page);
2040	return 0; /* retry */
2041	}
2042	ret \|= VM_FAULT_LOCKED;
2043	} else
2044	VM_BUG_ON_PAGE(!PageLocked(page), page);
2045	return ret;
2046	}
2047
2048	/*
2049	* Handle write page faults for pages that can be reused in the current vma
2050	*
2051	* This can happen either due to the mapping being with the VM_SHARED flag,
2052	* or due to us being the last reference standing to the page. In either
2053	* case, all we need to do here is to mark the page as writable and update
2054	* any related book-keeping.
2055	*/
2056	static inline int wp_page_reuse(struct mm_struct *mm,
2057	struct vm_area_struct *vma, unsigned long address,
2058	pte_t page_table, spinlock_t ptl, pte_t orig_pte,
2059	struct page *page, int page_mkwrite,
2060	int dirty_shared)
2061	__releases(ptl)
2062	{
2063	pte_t entry;
2064	/*
2065	* Clear the pages cpupid information as the existing
2066	* information potentially belongs to a now completely
2067	* unrelated process.
2068	*/
2069	if (page)
2070	page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2071
2072	flush_cache_page(vma, address, pte_pfn(orig_pte));
2073	entry = pte_mkyoung(orig_pte);
2074	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2075	if (ptep_set_access_flags(vma, address, page_table, entry, 1))
2076	update_mmu_cache(vma, address, page_table);
2077	pte_unmap_unlock(page_table, ptl);
2078
2079	if (dirty_shared) {
2080	struct address_space *mapping;
2081	int dirtied;
2082
2083	if (!page_mkwrite)
2084	lock_page(page);
2085
2086	dirtied = set_page_dirty(page);
2087	VM_BUG_ON_PAGE(PageAnon(page), page);
2088	mapping = page->mapping;
2089	unlock_page(page);
2090	put_page(page);
2091
2092	if ((dirtied \|\| page_mkwrite) && mapping) {
2093	/*
2094	* Some device drivers do not set page.mapping
2095	* but still dirty their pages
2096	*/
2097	balance_dirty_pages_ratelimited(mapping);
2098	}
2099
2100	if (!page_mkwrite)
2101	file_update_time(vma->vm_file);
2102	}
2103
2104	return VM_FAULT_WRITE;
2105	}
2106
2107	/*
2108	* Handle the case of a page which we actually need to copy to a new page.
2109	*
2110	* Called with mmap_sem locked and the old page referenced, but
2111	* without the ptl held.
2112	*
2113	* High level logic flow:
2114	*
2115	* - Allocate a page, copy the content of the old page to the new one.
2116	* - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2117	* - Take the PTL. If the pte changed, bail out and release the allocated page
2118	* - If the pte is still the way we remember it, update the page table and all
2119	* relevant references. This includes dropping the reference the page-table
2120	* held to the old page, as well as updating the rmap.
2121	* - In any case, unlock the PTL and drop the reference we took to the old page.
2122	*/
2123	static int wp_page_copy(struct mm_struct mm, struct vm_area_struct vma,
2124	unsigned long address, pte_t page_table, pmd_t pmd,
2125	pte_t orig_pte, struct page *old_page)
2126	{
2127	struct page *new_page = NULL;
2128	spinlock_t *ptl = NULL;
2129	pte_t entry;
2130	int page_copied = 0;
2131	const unsigned long mmun_start = address & PAGE_MASK; /* For mmu_notifiers */
2132	const unsigned long mmun_end = mmun_start + PAGE_SIZE; /* For mmu_notifiers */
2133	struct mem_cgroup *memcg;
2134
2135	if (unlikely(anon_vma_prepare(vma)))
2136	goto oom;
2137
2138	if (is_zero_pfn(pte_pfn(orig_pte))) {
2139	new_page = alloc_zeroed_user_highpage_movable(vma, address);
2140	if (!new_page)
2141	goto oom;
2142	} else {
2143	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2144	if (!new_page)
2145	goto oom;
2146	cow_user_page(new_page, old_page, address, vma);
2147	}
2148
2149	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2150	goto oom_free_new;
2151
2152	__SetPageUptodate(new_page);
2153
2154	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2155
2156	/*
2157	* Re-check the pte - we dropped the lock
2158	*/
2159	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2160	if (likely(pte_same(*page_table, orig_pte))) {
2161	if (old_page) {
2162	if (!PageAnon(old_page)) {
2163	dec_mm_counter_fast(mm,
2164	mm_counter_file(old_page));
2165	inc_mm_counter_fast(mm, MM_ANONPAGES);
2166	}
2167	} else {
2168	inc_mm_counter_fast(mm, MM_ANONPAGES);
2169	}
2170	flush_cache_page(vma, address, pte_pfn(orig_pte));
2171	entry = mk_pte(new_page, vma->vm_page_prot);
2172	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2173	/*
2174	* Clear the pte entry and flush it first, before updating the
2175	* pte with the new entry. This will avoid a race condition
2176	* seen in the presence of one thread doing SMC and another
2177	* thread doing COW.
2178	*/
2179	ptep_clear_flush_notify(vma, address, page_table);
2180	page_add_new_anon_rmap(new_page, vma, address, false);
2181	mem_cgroup_commit_charge(new_page, memcg, false, false);
2182	lru_cache_add_active_or_unevictable(new_page, vma);
2183	/*
2184	* We call the notify macro here because, when using secondary
2185	* mmu page tables (such as kvm shadow page tables), we want the
2186	* new page to be mapped directly into the secondary page table.
2187	*/
2188	set_pte_at_notify(mm, address, page_table, entry);
2189	update_mmu_cache(vma, address, page_table);
2190	if (old_page) {
2191	/*
2192	* Only after switching the pte to the new page may
2193	* we remove the mapcount here. Otherwise another
2194	* process may come and find the rmap count decremented
2195	* before the pte is switched to the new page, and
2196	* "reuse" the old page writing into it while our pte
2197	* here still points into it and can be read by other
2198	* threads.
2199	*
2200	* The critical issue is to order this
2201	* page_remove_rmap with the ptp_clear_flush above.
2202	* Those stores are ordered by (if nothing else,)
2203	* the barrier present in the atomic_add_negative
2204	* in page_remove_rmap.
2205	*
2206	* Then the TLB flush in ptep_clear_flush ensures that
2207	* no process can access the old page before the
2208	* decremented mapcount is visible. And the old page
2209	* cannot be reused until after the decremented
2210	* mapcount is visible. So transitively, TLBs to
2211	* old page will be flushed before it can be reused.
2212	*/
2213	page_remove_rmap(old_page, false);
2214	}
2215
2216	/* Free the old page.. */
2217	new_page = old_page;
2218	page_copied = 1;
2219	} else {
2220	mem_cgroup_cancel_charge(new_page, memcg, false);
2221	}
2222
2223	if (new_page)
2224	put_page(new_page);
2225
2226	pte_unmap_unlock(page_table, ptl);
2227	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2228	if (old_page) {
2229	/*
2230	* Don't let another task, with possibly unlocked vma,
2231	* keep the mlocked page.
2232	*/
2233	if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2234	lock_page(old_page); /* LRU manipulation */
2235	if (PageMlocked(old_page))
2236	munlock_vma_page(old_page);
2237	unlock_page(old_page);
2238	}
2239	put_page(old_page);
2240	}
2241	return page_copied ? VM_FAULT_WRITE : 0;
2242	oom_free_new:
2243	put_page(new_page);
2244	oom:
2245	if (old_page)
2246	put_page(old_page);
2247	return VM_FAULT_OOM;
2248	}
2249
2250	/*
2251	* Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2252	* mapping
2253	*/
2254	static int wp_pfn_shared(struct mm_struct *mm,
2255	struct vm_area_struct *vma, unsigned long address,
2256	pte_t page_table, spinlock_t ptl, pte_t orig_pte,
2257	pmd_t *pmd)
2258	{
2259	if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2260	struct vm_fault vmf = {
2261	.page = NULL,
2262	.pgoff = linear_page_index(vma, address),
2263	.virtual_address = (void __user *)(address & PAGE_MASK),
2264	.flags = FAULT_FLAG_WRITE \| FAULT_FLAG_MKWRITE,
2265	};
2266	int ret;
2267
2268	pte_unmap_unlock(page_table, ptl);
2269	ret = vma->vm_ops->pfn_mkwrite(vma, &vmf);
2270	if (ret & VM_FAULT_ERROR)
2271	return ret;
2272	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2273	/*
2274	* We might have raced with another page fault while we
2275	* released the pte_offset_map_lock.
2276	*/
2277	if (!pte_same(*page_table, orig_pte)) {
2278	pte_unmap_unlock(page_table, ptl);
2279	return 0;
2280	}
2281	}
2282	return wp_page_reuse(mm, vma, address, page_table, ptl, orig_pte,
2283	NULL, 0, 0);
2284	}
2285
2286	static int wp_page_shared(struct mm_struct mm, struct vm_area_struct vma,
2287	unsigned long address, pte_t *page_table,
2288	pmd_t pmd, spinlock_t ptl, pte_t orig_pte,
2289	struct page *old_page)
2290	__releases(ptl)
2291	{
2292	int page_mkwrite = 0;
2293
2294	get_page(old_page);
2295
2296	if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2297	int tmp;
2298
2299	pte_unmap_unlock(page_table, ptl);
2300	tmp = do_page_mkwrite(vma, old_page, address);
2301	if (unlikely(!tmp \|\| (tmp &
2302	(VM_FAULT_ERROR \| VM_FAULT_NOPAGE)))) {
2303	put_page(old_page);
2304	return tmp;
2305	}
2306	/*
2307	* Since we dropped the lock we need to revalidate
2308	* the PTE as someone else may have changed it. If
2309	* they did, we just return, as we can count on the
2310	* MMU to tell us if they didn't also make it writable.
2311	*/
2312	page_table = pte_offset_map_lock(mm, pmd, address,
2313	&ptl);
2314	if (!pte_same(*page_table, orig_pte)) {
2315	unlock_page(old_page);
2316	pte_unmap_unlock(page_table, ptl);
2317	put_page(old_page);
2318	return 0;
2319	}
2320	page_mkwrite = 1;
2321	}
2322
2323	return wp_page_reuse(mm, vma, address, page_table, ptl,
2324	orig_pte, old_page, page_mkwrite, 1);
2325	}
2326
2327	/*
2328	* This routine handles present pages, when users try to write
2329	* to a shared page. It is done by copying the page to a new address
2330	* and decrementing the shared-page counter for the old page.
2331	*
2332	* Note that this routine assumes that the protection checks have been
2333	* done by the caller (the low-level page fault routine in most cases).
2334	* Thus we can safely just mark it writable once we've done any necessary
2335	* COW.
2336	*
2337	* We also mark the page dirty at this point even though the page will
2338	* change only once the write actually happens. This avoids a few races,
2339	* and potentially makes it more efficient.
2340	*
2341	* We enter with non-exclusive mmap_sem (to exclude vma changes,
2342	* but allow concurrent faults), with pte both mapped and locked.
2343	* We return with mmap_sem still held, but pte unmapped and unlocked.
2344	*/
2345	static int do_wp_page(struct mm_struct mm, struct vm_area_struct vma,
2346	unsigned long address, pte_t page_table, pmd_t pmd,
2347	spinlock_t *ptl, pte_t orig_pte)
2348	__releases(ptl)
2349	{
2350	struct page *old_page;
2351
2352	old_page = vm_normal_page(vma, address, orig_pte);
2353	if (!old_page) {
2354	/*
2355	* VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2356	* VM_PFNMAP VMA.
2357	*
2358	* We should not cow pages in a shared writeable mapping.
2359	* Just mark the pages writable and/or call ops->pfn_mkwrite.
2360	*/
2361	if ((vma->vm_flags & (VM_WRITE\|VM_SHARED)) ==
2362	(VM_WRITE\|VM_SHARED))
2363	return wp_pfn_shared(mm, vma, address, page_table, ptl,
2364	orig_pte, pmd);
2365
2366	pte_unmap_unlock(page_table, ptl);
2367	return wp_page_copy(mm, vma, address, page_table, pmd,
2368	orig_pte, old_page);
2369	}
2370
2371	/*
2372	* Take out anonymous pages first, anonymous shared vmas are
2373	* not dirty accountable.
2374	*/
2375	if (PageAnon(old_page) && !PageKsm(old_page)) {
2376	int total_mapcount;
2377	if (!trylock_page(old_page)) {
2378	get_page(old_page);
2379	pte_unmap_unlock(page_table, ptl);
2380	lock_page(old_page);
2381	page_table = pte_offset_map_lock(mm, pmd, address,
2382	&ptl);
2383	if (!pte_same(*page_table, orig_pte)) {
2384	unlock_page(old_page);
2385	pte_unmap_unlock(page_table, ptl);
2386	put_page(old_page);
2387	return 0;
2388	}
2389	put_page(old_page);
2390	}
2391	if (reuse_swap_page(old_page, &total_mapcount)) {
2392	if (total_mapcount == 1) {
2393	/*
2394	* The page is all ours. Move it to
2395	* our anon_vma so the rmap code will
2396	* not search our parent or siblings.
2397	* Protected against the rmap code by
2398	* the page lock.
2399	*/
2400	page_move_anon_rmap(compound_head(old_page),
2401	vma, address);
2402	}
2403	unlock_page(old_page);
2404	return wp_page_reuse(mm, vma, address, page_table, ptl,
2405	orig_pte, old_page, 0, 0);
2406	}
2407	unlock_page(old_page);
2408	} else if (unlikely((vma->vm_flags & (VM_WRITE\|VM_SHARED)) ==
2409	(VM_WRITE\|VM_SHARED))) {
2410	return wp_page_shared(mm, vma, address, page_table, pmd,
2411	ptl, orig_pte, old_page);
2412	}
2413
2414	/*
2415	* Ok, we need to copy. Oh, well..
2416	*/
2417	get_page(old_page);
2418
2419	pte_unmap_unlock(page_table, ptl);
2420	return wp_page_copy(mm, vma, address, page_table, pmd,
2421	orig_pte, old_page);
2422	}
2423
2424	static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2425	unsigned long start_addr, unsigned long end_addr,
2426	struct zap_details *details)
2427	{
2428	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2429	}
2430
2431	static inline void unmap_mapping_range_tree(struct rb_root *root,
2432	struct zap_details *details)
2433	{
2434	struct vm_area_struct *vma;
2435	pgoff_t vba, vea, zba, zea;
2436
2437	vma_interval_tree_foreach(vma, root,
2438	details->first_index, details->last_index) {
2439
2440	vba = vma->vm_pgoff;
2441	vea = vba + vma_pages(vma) - 1;
2442	zba = details->first_index;
2443	if (zba < vba)
2444	zba = vba;
2445	zea = details->last_index;
2446	if (zea > vea)
2447	zea = vea;
2448
2449	unmap_mapping_range_vma(vma,
2450	((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2451	((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2452	details);
2453	}
2454	}
2455
2456	/**
2457	* unmap_mapping_range - unmap the portion of all mmaps in the specified
2458	* address_space corresponding to the specified page range in the underlying
2459	* file.
2460	*
2461	* @mapping: the address space containing mmaps to be unmapped.
2462	* @holebegin: byte in first page to unmap, relative to the start of
2463	* the underlying file. This will be rounded down to a PAGE_SIZE
2464	* boundary. Note that this is different from truncate_pagecache(), which
2465	* must keep the partial page. In contrast, we must get rid of
2466	* partial pages.
2467	* @holelen: size of prospective hole in bytes. This will be rounded
2468	* up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2469	* end of the file.
2470	* @even_cows: 1 when truncating a file, unmap even private COWed pages;
2471	* but 0 when invalidating pagecache, don't throw away private data.
2472	*/
2473	void unmap_mapping_range(struct address_space *mapping,
2474	loff_t const holebegin, loff_t const holelen, int even_cows)
2475	{
2476	struct zap_details details = { };
2477	pgoff_t hba = holebegin >> PAGE_SHIFT;
2478	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2479
2480	/* Check for overflow. */
2481	if (sizeof(holelen) > sizeof(hlen)) {
2482	long long holeend =
2483	(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2484	if (holeend & ~(long long)ULONG_MAX)
2485	hlen = ULONG_MAX - hba + 1;
2486	}
2487
2488	details.check_mapping = even_cows? NULL: mapping;
2489	details.first_index = hba;
2490	details.last_index = hba + hlen - 1;
2491	if (details.last_index < details.first_index)
2492	details.last_index = ULONG_MAX;
2493
2494
2495	/* DAX uses i_mmap_lock to serialise file truncate vs page fault */
2496	i_mmap_lock_write(mapping);
2497	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2498	unmap_mapping_range_tree(&mapping->i_mmap, &details);
2499	i_mmap_unlock_write(mapping);
2500	}
2501	EXPORT_SYMBOL(unmap_mapping_range);
2502
2503	/*
2504	* We enter with non-exclusive mmap_sem (to exclude vma changes,
2505	* but allow concurrent faults), and pte mapped but not yet locked.
2506	* We return with pte unmapped and unlocked.
2507	*
2508	* We return with the mmap_sem locked or unlocked in the same cases
2509	* as does filemap_fault().
2510	*/
2511	static int do_swap_page(struct mm_struct mm, struct vm_area_struct vma,
2512	unsigned long address, pte_t page_table, pmd_t pmd,
2513	unsigned int flags, pte_t orig_pte)
2514	{
2515	spinlock_t *ptl;
2516	struct page page, swapcache;
2517	struct mem_cgroup *memcg;
2518	swp_entry_t entry;
2519	pte_t pte;
2520	int locked;
2521	int exclusive = 0;
2522	int ret = 0;
2523
2524	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2525	goto out;
2526
2527	entry = pte_to_swp_entry(orig_pte);
2528	if (unlikely(non_swap_entry(entry))) {
2529	if (is_migration_entry(entry)) {
2530	migration_entry_wait(mm, pmd, address);
2531	} else if (is_hwpoison_entry(entry)) {
2532	ret = VM_FAULT_HWPOISON;
2533	} else {
2534	print_bad_pte(vma, address, orig_pte, NULL);
2535	ret = VM_FAULT_SIGBUS;
2536	}
2537	goto out;
2538	}
2539	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2540	page = lookup_swap_cache(entry);
2541	if (!page) {
2542	page = swapin_readahead(entry,
2543	GFP_HIGHUSER_MOVABLE, vma, address);
2544	if (!page) {
2545	/*
2546	* Back out if somebody else faulted in this pte
2547	* while we released the pte lock.
2548	*/
2549	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2550	if (likely(pte_same(*page_table, orig_pte)))
2551	ret = VM_FAULT_OOM;
2552	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2553	goto unlock;
2554	}
2555
2556	/* Had to read the page from swap area: Major fault */
2557	ret = VM_FAULT_MAJOR;
2558	count_vm_event(PGMAJFAULT);
2559	mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2560	} else if (PageHWPoison(page)) {
2561	/*
2562	* hwpoisoned dirty swapcache pages are kept for killing
2563	* owner processes (which may be unknown at hwpoison time)
2564	*/
2565	ret = VM_FAULT_HWPOISON;
2566	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2567	swapcache = page;
2568	goto out_release;
2569	}
2570
2571	swapcache = page;
2572	locked = lock_page_or_retry(page, mm, flags);
2573
2574	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2575	if (!locked) {
2576	ret \|= VM_FAULT_RETRY;
2577	goto out_release;
2578	}
2579
2580	/*
2581	* Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2582	* release the swapcache from under us. The page pin, and pte_same
2583	* test below, are not enough to exclude that. Even if it is still
2584	* swapcache, we need to check that the page's swap has not changed.
2585	*/
2586	if (unlikely(!PageSwapCache(page) \|\| page_private(page) != entry.val))
2587	goto out_page;
2588
2589	page = ksm_might_need_to_copy(page, vma, address);
2590	if (unlikely(!page)) {
2591	ret = VM_FAULT_OOM;
2592	page = swapcache;
2593	goto out_page;
2594	}
2595
2596	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg, false)) {
2597	ret = VM_FAULT_OOM;
2598	goto out_page;
2599	}
2600
2601	/*
2602	* Back out if somebody else already faulted in this pte.
2603	*/
2604	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2605	if (unlikely(!pte_same(*page_table, orig_pte)))
2606	goto out_nomap;
2607
2608	if (unlikely(!PageUptodate(page))) {
2609	ret = VM_FAULT_SIGBUS;
2610	goto out_nomap;
2611	}
2612
2613	/*
2614	* The page isn't present yet, go ahead with the fault.
2615	*
2616	* Be careful about the sequence of operations here.
2617	* To get its accounting right, reuse_swap_page() must be called
2618	* while the page is counted on swap but not yet in mapcount i.e.
2619	* before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2620	* must be called after the swap_free(), or it will never succeed.
2621	*/
2622
2623	inc_mm_counter_fast(mm, MM_ANONPAGES);
2624	dec_mm_counter_fast(mm, MM_SWAPENTS);
2625	pte = mk_pte(page, vma->vm_page_prot);
2626	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
2627	pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2628	flags &= ~FAULT_FLAG_WRITE;
2629	ret \|= VM_FAULT_WRITE;
2630	exclusive = RMAP_EXCLUSIVE;
2631	}
2632	flush_icache_page(vma, page);
2633	if (pte_swp_soft_dirty(orig_pte))
2634	pte = pte_mksoft_dirty(pte);
2635	set_pte_at(mm, address, page_table, pte);
2636	if (page == swapcache) {
2637	do_page_add_anon_rmap(page, vma, address, exclusive);
2638	mem_cgroup_commit_charge(page, memcg, true, false);
2639	} else { /* ksm created a completely new copy */
2640	page_add_new_anon_rmap(page, vma, address, false);
2641	mem_cgroup_commit_charge(page, memcg, false, false);
2642	lru_cache_add_active_or_unevictable(page, vma);
2643	}
2644
2645	swap_free(entry);
2646	if (mem_cgroup_swap_full(page) \|\|
2647	(vma->vm_flags & VM_LOCKED) \|\| PageMlocked(page))
2648	try_to_free_swap(page);
2649	unlock_page(page);
2650	if (page != swapcache) {
2651	/*
2652	* Hold the lock to avoid the swap entry to be reused
2653	* until we take the PT lock for the pte_same() check
2654	* (to avoid false positives from pte_same). For
2655	* further safety release the lock after the swap_free
2656	* so that the swap count won't change under a
2657	* parallel locked swapcache.
2658	*/
2659	unlock_page(swapcache);
2660	put_page(swapcache);
2661	}
2662
2663	if (flags & FAULT_FLAG_WRITE) {
2664	ret \|= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2665	if (ret & VM_FAULT_ERROR)
2666	ret &= VM_FAULT_ERROR;
2667	goto out;
2668	}
2669
2670	/* No need to invalidate - it was non-present before */
2671	update_mmu_cache(vma, address, page_table);
2672	unlock:
2673	pte_unmap_unlock(page_table, ptl);
2674	out:
2675	return ret;
2676	out_nomap:
2677	mem_cgroup_cancel_charge(page, memcg, false);
2678	pte_unmap_unlock(page_table, ptl);
2679	out_page:
2680	unlock_page(page);
2681	out_release:
2682	put_page(page);
2683	if (page != swapcache) {
2684	unlock_page(swapcache);
2685	put_page(swapcache);
2686	}
2687	return ret;
2688	}
2689
2690	/*
2691	* This is like a special single-page "expand_{down\|up}wards()",
2692	* except we must first make sure that 'address{-\|+}PAGE_SIZE'
2693	* doesn't hit another vma.
2694	*/
2695	static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2696	{
2697	address &= PAGE_MASK;
2698	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2699	struct vm_area_struct *prev = vma->vm_prev;
2700
2701	/*
2702	* Is there a mapping abutting this one below?
2703	*
2704	* That's only ok if it's the same stack mapping
2705	* that has gotten split..
2706	*/
2707	if (prev && prev->vm_end == address)
2708	return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2709
2710	return expand_downwards(vma, address - PAGE_SIZE);
2711	}
2712	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
2713	struct vm_area_struct *next = vma->vm_next;
2714
2715	/* As VM_GROWSDOWN but s/below/above/ */
2716	if (next && next->vm_start == address + PAGE_SIZE)
2717	return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
2718
2719	return expand_upwards(vma, address + PAGE_SIZE);
2720	}
2721	return 0;
2722	}
2723
2724	/*
2725	* We enter with non-exclusive mmap_sem (to exclude vma changes,
2726	* but allow concurrent faults), and pte mapped but not yet locked.
2727	* We return with mmap_sem still held, but pte unmapped and unlocked.
2728	*/
2729	static int do_anonymous_page(struct mm_struct mm, struct vm_area_struct vma,
2730	unsigned long address, pte_t page_table, pmd_t pmd,
2731	unsigned int flags)
2732	{
2733	struct mem_cgroup *memcg;
2734	struct page *page;
2735	spinlock_t *ptl;
2736	pte_t entry;
2737
2738	pte_unmap(page_table);
2739
2740	/* File mapping without ->vm_ops ? */
2741	if (vma->vm_flags & VM_SHARED)
2742	return VM_FAULT_SIGBUS;
2743
2744	/* Check if we need to add a guard page to the stack */
2745	if (check_stack_guard_page(vma, address) < 0)
2746	return VM_FAULT_SIGSEGV;
2747
2748	/* Use the zero-page for reads */
2749	if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) {
2750	entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
2751	vma->vm_page_prot));
2752	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2753	if (!pte_none(*page_table))
2754	goto unlock;
2755	/* Deliver the page fault to userland, check inside PT lock */
2756	if (userfaultfd_missing(vma)) {
2757	pte_unmap_unlock(page_table, ptl);
2758	return handle_userfault(vma, address, flags,
2759	VM_UFFD_MISSING);
2760	}
2761	goto setpte;
2762	}
2763
2764	/* Allocate our own private page. */
2765	if (unlikely(anon_vma_prepare(vma)))
2766	goto oom;
2767	page = alloc_zeroed_user_highpage_movable(vma, address);
2768	if (!page)
2769	goto oom;
2770
2771	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg, false))
2772	goto oom_free_page;
2773
2774	/*
2775	* The memory barrier inside __SetPageUptodate makes sure that
2776	* preceeding stores to the page contents become visible before
2777	* the set_pte_at() write.
2778	*/
2779	__SetPageUptodate(page);
2780
2781	entry = mk_pte(page, vma->vm_page_prot);
2782	if (vma->vm_flags & VM_WRITE)
2783	entry = pte_mkwrite(pte_mkdirty(entry));
2784
2785	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2786	if (!pte_none(*page_table))
2787	goto release;
2788
2789	/* Deliver the page fault to userland, check inside PT lock */
2790	if (userfaultfd_missing(vma)) {
2791	pte_unmap_unlock(page_table, ptl);
2792	mem_cgroup_cancel_charge(page, memcg, false);
2793	put_page(page);
2794	return handle_userfault(vma, address, flags,
2795	VM_UFFD_MISSING);
2796	}
2797
2798	inc_mm_counter_fast(mm, MM_ANONPAGES);
2799	page_add_new_anon_rmap(page, vma, address, false);
2800	mem_cgroup_commit_charge(page, memcg, false, false);
2801	lru_cache_add_active_or_unevictable(page, vma);
2802	setpte:
2803	set_pte_at(mm, address, page_table, entry);
2804
2805	/* No need to invalidate - it was non-present before */
2806	update_mmu_cache(vma, address, page_table);
2807	unlock:
2808	pte_unmap_unlock(page_table, ptl);
2809	return 0;
2810	release:
2811	mem_cgroup_cancel_charge(page, memcg, false);
2812	put_page(page);
2813	goto unlock;
2814	oom_free_page:
2815	put_page(page);
2816	oom:
2817	return VM_FAULT_OOM;
2818	}
2819
2820	/*
2821	* The mmap_sem must have been held on entry, and may have been
2822	* released depending on flags and vma->vm_ops->fault() return value.
2823	* See filemap_fault() and __lock_page_retry().
2824	*/
2825	static int __do_fault(struct vm_area_struct *vma, unsigned long address,
2826	pgoff_t pgoff, unsigned int flags,
2827	struct page cow_page, struct page *page)
2828	{
2829	struct vm_fault vmf;
2830	int ret;
2831
2832	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2833	vmf.pgoff = pgoff;
2834	vmf.flags = flags;
2835	vmf.page = NULL;
2836	vmf.gfp_mask = __get_fault_gfp_mask(vma);
2837	vmf.cow_page = cow_page;
2838
2839	ret = vma->vm_ops->fault(vma, &vmf);
2840	if (unlikely(ret & (VM_FAULT_ERROR \| VM_FAULT_NOPAGE \| VM_FAULT_RETRY)))
2841	return ret;
2842	if (!vmf.page)
2843	goto out;
2844
2845	if (unlikely(PageHWPoison(vmf.page))) {
2846	if (ret & VM_FAULT_LOCKED)
2847	unlock_page(vmf.page);
2848	put_page(vmf.page);
2849	return VM_FAULT_HWPOISON;
2850	}
2851
2852	if (unlikely(!(ret & VM_FAULT_LOCKED)))
2853	lock_page(vmf.page);
2854	else
2855	VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);
2856
2857	out:
2858	*page = vmf.page;
2859	return ret;
2860	}
2861
2862	/**
2863	* do_set_pte - setup new PTE entry for given page and add reverse page mapping.
2864	*
2865	* @vma: virtual memory area
2866	* @address: user virtual address
2867	* @page: page to map
2868	* @pte: pointer to target page table entry
2869	* @write: true, if new entry is writable
2870	* @anon: true, if it's anonymous page
2871	*
2872	* Caller must hold page table lock relevant for @pte.
2873	*
2874	* Target users are page handler itself and implementations of
2875	* vm_ops->map_pages.
2876	*/
2877	void do_set_pte(struct vm_area_struct *vma, unsigned long address,
2878	struct page page, pte_t pte, bool write, bool anon)
2879	{
2880	pte_t entry;
2881
2882	flush_icache_page(vma, page);
2883	entry = mk_pte(page, vma->vm_page_prot);
2884	if (write)
2885	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2886	if (anon) {
2887	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2888	page_add_new_anon_rmap(page, vma, address, false);
2889	} else {
2890	inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
2891	page_add_file_rmap(page);
2892	}
2893	set_pte_at(vma->vm_mm, address, pte, entry);
2894
2895	/* no need to invalidate: a not-present page won't be cached */
2896	update_mmu_cache(vma, address, pte);
2897	}
2898
2899	static unsigned long fault_around_bytes __read_mostly =
2900	rounddown_pow_of_two(65536);
2901
2902	#ifdef CONFIG_DEBUG_FS
2903	static int fault_around_bytes_get(void data, u64 val)
2904	{
2905	*val = fault_around_bytes;
2906	return 0;
2907	}
2908
2909	/*
2910	* fault_around_pages() and fault_around_mask() expects fault_around_bytes
2911	* rounded down to nearest page order. It's what do_fault_around() expects to
2912	* see.
2913	*/
2914	static int fault_around_bytes_set(void *data, u64 val)
2915	{
2916	if (val / PAGE_SIZE > PTRS_PER_PTE)
2917	return -EINVAL;
2918	if (val > PAGE_SIZE)
2919	fault_around_bytes = rounddown_pow_of_two(val);
2920	else
2921	fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
2922	return 0;
2923	}
2924	DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
2925	fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
2926
2927	static int __init fault_around_debugfs(void)
2928	{
2929	void *ret;
2930
2931	ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
2932	&fault_around_bytes_fops);
2933	if (!ret)
2934	pr_warn("Failed to create fault_around_bytes in debugfs");
2935	return 0;
2936	}
2937	late_initcall(fault_around_debugfs);
2938	#endif
2939
2940	/*
2941	* do_fault_around() tries to map few pages around the fault address. The hope
2942	* is that the pages will be needed soon and this will lower the number of
2943	* faults to handle.
2944	*
2945	* It uses vm_ops->map_pages() to map the pages, which skips the page if it's
2946	* not ready to be mapped: not up-to-date, locked, etc.
2947	*
2948	* This function is called with the page table lock taken. In the split ptlock
2949	* case the page table lock only protects only those entries which belong to
2950	* the page table corresponding to the fault address.
2951	*
2952	* This function doesn't cross the VMA boundaries, in order to call map_pages()
2953	* only once.
2954	*
2955	* fault_around_pages() defines how many pages we'll try to map.
2956	* do_fault_around() expects it to return a power of two less than or equal to
2957	* PTRS_PER_PTE.
2958	*
2959	* The virtual address of the area that we map is naturally aligned to the
2960	* fault_around_pages() value (and therefore to page order). This way it's
2961	* easier to guarantee that we don't cross page table boundaries.
2962	*/
2963	static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
2964	pte_t *pte, pgoff_t pgoff, unsigned int flags)
2965	{
2966	unsigned long start_addr, nr_pages, mask;
2967	pgoff_t max_pgoff;
2968	struct vm_fault vmf;
2969	int off;
2970
2971	nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
2972	mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
2973
2974	start_addr = max(address & mask, vma->vm_start);
2975	off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
2976	pte -= off;
2977	pgoff -= off;
2978
2979	/*
2980	* max_pgoff is either end of page table or end of vma
2981	* or fault_around_pages() from pgoff, depending what is nearest.
2982	*/
2983	max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
2984	PTRS_PER_PTE - 1;
2985	max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1,
2986	pgoff + nr_pages - 1);
2987
2988	/* Check if it makes any sense to call ->map_pages */
2989	while (!pte_none(*pte)) {
2990	if (++pgoff > max_pgoff)
2991	return;
2992	start_addr += PAGE_SIZE;
2993	if (start_addr >= vma->vm_end)
2994	return;
2995	pte++;
2996	}
2997
2998	vmf.virtual_address = (void __user *) start_addr;
2999	vmf.pte = pte;
3000	vmf.pgoff = pgoff;
3001	vmf.max_pgoff = max_pgoff;
3002	vmf.flags = flags;
3003	vmf.gfp_mask = __get_fault_gfp_mask(vma);
3004	vma->vm_ops->map_pages(vma, &vmf);
3005	}
3006
3007	static int do_read_fault(struct mm_struct mm, struct vm_area_struct vma,
3008	unsigned long address, pmd_t *pmd,
3009	pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3010	{
3011	struct page *fault_page;
3012	spinlock_t *ptl;
3013	pte_t *pte;
3014	int ret = 0;
3015
3016	/*
3017	* Let's call ->map_pages() first and use ->fault() as fallback
3018	* if page by the offset is not ready to be mapped (cold cache or
3019	* something).
3020	*/
3021	if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3022	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3023	do_fault_around(vma, address, pte, pgoff, flags);
3024	if (!pte_same(*pte, orig_pte))
3025	goto unlock_out;
3026	pte_unmap_unlock(pte, ptl);
3027	}
3028
3029	ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
3030	if (unlikely(ret & (VM_FAULT_ERROR \| VM_FAULT_NOPAGE \| VM_FAULT_RETRY)))
3031	return ret;
3032
3033	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3034	if (unlikely(!pte_same(*pte, orig_pte))) {
3035	pte_unmap_unlock(pte, ptl);
3036	unlock_page(fault_page);
3037	put_page(fault_page);
3038	return ret;
3039	}
3040	do_set_pte(vma, address, fault_page, pte, false, false);
3041	unlock_page(fault_page);
3042	unlock_out:
3043	pte_unmap_unlock(pte, ptl);
3044	return ret;
3045	}
3046
3047	static int do_cow_fault(struct mm_struct mm, struct vm_area_struct vma,
3048	unsigned long address, pmd_t *pmd,
3049	pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3050	{
3051	struct page fault_page, new_page;
3052	struct mem_cgroup *memcg;
3053	spinlock_t *ptl;
3054	pte_t *pte;
3055	int ret;
3056
3057	if (unlikely(anon_vma_prepare(vma)))
3058	return VM_FAULT_OOM;
3059
3060	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3061	if (!new_page)
3062	return VM_FAULT_OOM;
3063
3064	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false)) {
3065	put_page(new_page);
3066	return VM_FAULT_OOM;
3067	}
3068
3069	ret = __do_fault(vma, address, pgoff, flags, new_page, &fault_page);
3070	if (unlikely(ret & (VM_FAULT_ERROR \| VM_FAULT_NOPAGE \| VM_FAULT_RETRY)))
3071	goto uncharge_out;
3072
3073	if (fault_page)
3074	copy_user_highpage(new_page, fault_page, address, vma);
3075	__SetPageUptodate(new_page);
3076
3077	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3078	if (unlikely(!pte_same(*pte, orig_pte))) {
3079	pte_unmap_unlock(pte, ptl);
3080	if (fault_page) {
3081	unlock_page(fault_page);
3082	put_page(fault_page);
3083	} else {
3084	/*
3085	* The fault handler has no page to lock, so it holds
3086	* i_mmap_lock for read to protect against truncate.
3087	*/
3088	i_mmap_unlock_read(vma->vm_file->f_mapping);
3089	}
3090	goto uncharge_out;
3091	}
3092	do_set_pte(vma, address, new_page, pte, true, true);
3093	mem_cgroup_commit_charge(new_page, memcg, false, false);
3094	lru_cache_add_active_or_unevictable(new_page, vma);
3095	pte_unmap_unlock(pte, ptl);
3096	if (fault_page) {
3097	unlock_page(fault_page);
3098	put_page(fault_page);
3099	} else {
3100	/*
3101	* The fault handler has no page to lock, so it holds
3102	* i_mmap_lock for read to protect against truncate.
3103	*/
3104	i_mmap_unlock_read(vma->vm_file->f_mapping);
3105	}
3106	return ret;
3107	uncharge_out:
3108	mem_cgroup_cancel_charge(new_page, memcg, false);
3109	put_page(new_page);
3110	return ret;
3111	}
3112
3113	static int do_shared_fault(struct mm_struct mm, struct vm_area_struct vma,
3114	unsigned long address, pmd_t *pmd,
3115	pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3116	{
3117	struct page *fault_page;
3118	struct address_space *mapping;
3119	spinlock_t *ptl;
3120	pte_t *pte;
3121	int dirtied = 0;
3122	int ret, tmp;
3123
3124	ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
3125	if (unlikely(ret & (VM_FAULT_ERROR \| VM_FAULT_NOPAGE \| VM_FAULT_RETRY)))
3126	return ret;
3127
3128	/*
3129	* Check if the backing address space wants to know that the page is
3130	* about to become writable
3131	*/
3132	if (vma->vm_ops->page_mkwrite) {
3133	unlock_page(fault_page);
3134	tmp = do_page_mkwrite(vma, fault_page, address);
3135	if (unlikely(!tmp \|\|
3136	(tmp & (VM_FAULT_ERROR \| VM_FAULT_NOPAGE)))) {
3137	put_page(fault_page);
3138	return tmp;
3139	}
3140	}
3141
3142	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3143	if (unlikely(!pte_same(*pte, orig_pte))) {
3144	pte_unmap_unlock(pte, ptl);
3145	unlock_page(fault_page);
3146	put_page(fault_page);
3147	return ret;
3148	}
3149	do_set_pte(vma, address, fault_page, pte, true, false);
3150	pte_unmap_unlock(pte, ptl);
3151
3152	if (set_page_dirty(fault_page))
3153	dirtied = 1;
3154	/*
3155	* Take a local copy of the address_space - page.mapping may be zeroed
3156	* by truncate after unlock_page(). The address_space itself remains
3157	* pinned by vma->vm_file's reference. We rely on unlock_page()'s
3158	* release semantics to prevent the compiler from undoing this copying.
3159	*/
3160	mapping = page_rmapping(fault_page);
3161	unlock_page(fault_page);
3162	if ((dirtied \|\| vma->vm_ops->page_mkwrite) && mapping) {
3163	/*
3164	* Some device drivers do not set page.mapping but still
3165	* dirty their pages
3166	*/
3167	balance_dirty_pages_ratelimited(mapping);
3168	}
3169
3170	if (!vma->vm_ops->page_mkwrite)
3171	file_update_time(vma->vm_file);
3172
3173	return ret;
3174	}
3175
3176	/*
3177	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3178	* but allow concurrent faults).
3179	* The mmap_sem may have been released depending on flags and our
3180	* return value. See filemap_fault() and __lock_page_or_retry().
3181	*/
3182	static int do_fault(struct mm_struct mm, struct vm_area_struct vma,
3183	unsigned long address, pte_t page_table, pmd_t pmd,
3184	unsigned int flags, pte_t orig_pte)
3185	{
3186	pgoff_t pgoff = linear_page_index(vma, address);
3187
3188	pte_unmap(page_table);
3189	/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3190	if (!vma->vm_ops->fault)
3191	return VM_FAULT_SIGBUS;
3192	if (!(flags & FAULT_FLAG_WRITE))
3193	return do_read_fault(mm, vma, address, pmd, pgoff, flags,
3194	orig_pte);
3195	if (!(vma->vm_flags & VM_SHARED))
3196	return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
3197	orig_pte);
3198	return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3199	}
3200
3201	static int numa_migrate_prep(struct page page, struct vm_area_struct vma,
3202	unsigned long addr, int page_nid,
3203	int *flags)
3204	{
3205	get_page(page);
3206
3207	count_vm_numa_event(NUMA_HINT_FAULTS);
3208	if (page_nid == numa_node_id()) {
3209	count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3210	*flags \|= TNF_FAULT_LOCAL;
3211	}
3212
3213	return mpol_misplaced(page, vma, addr);
3214	}
3215
3216	static int do_numa_page(struct mm_struct mm, struct vm_area_struct vma,
3217	unsigned long addr, pte_t pte, pte_t ptep, pmd_t pmd)
3218	{
3219	struct page *page = NULL;
3220	spinlock_t *ptl;
3221	int page_nid = -1;
3222	int last_cpupid;
3223	int target_nid;
3224	bool migrated = false;
3225	bool was_writable = pte_write(pte);
3226	int flags = 0;
3227
3228	/* A PROT_NONE fault should not end up here */
3229	BUG_ON(!(vma->vm_flags & (VM_READ \| VM_EXEC \| VM_WRITE)));
3230
3231	/*
3232	* The "pte" at this point cannot be used safely without
3233	* validation through pte_unmap_same(). It's of NUMA type but
3234	* the pfn may be screwed if the read is non atomic.
3235	*
3236	* We can safely just do a "set_pte_at()", because the old
3237	* page table entry is not accessible, so there would be no
3238	* concurrent hardware modifications to the PTE.
3239	*/
3240	ptl = pte_lockptr(mm, pmd);
3241	spin_lock(ptl);
3242	if (unlikely(!pte_same(*ptep, pte))) {
3243	pte_unmap_unlock(ptep, ptl);
3244	goto out;
3245	}
3246
3247	/* Make it present again */
3248	pte = pte_modify(pte, vma->vm_page_prot);
3249	pte = pte_mkyoung(pte);
3250	if (was_writable)
3251	pte = pte_mkwrite(pte);
3252	set_pte_at(mm, addr, ptep, pte);
3253	update_mmu_cache(vma, addr, ptep);
3254
3255	page = vm_normal_page(vma, addr, pte);
3256	if (!page) {
3257	pte_unmap_unlock(ptep, ptl);
3258	return 0;
3259	}
3260
3261	/* TODO: handle PTE-mapped THP */
3262	if (PageCompound(page)) {
3263	pte_unmap_unlock(ptep, ptl);
3264	return 0;
3265	}
3266
3267	/*
3268	* Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3269	* much anyway since they can be in shared cache state. This misses
3270	* the case where a mapping is writable but the process never writes
3271	* to it but pte_write gets cleared during protection updates and
3272	* pte_dirty has unpredictable behaviour between PTE scan updates,
3273	* background writeback, dirty balancing and application behaviour.
3274	*/
3275	if (!(vma->vm_flags & VM_WRITE))
3276	flags \|= TNF_NO_GROUP;
3277
3278	/*
3279	* Flag if the page is shared between multiple address spaces. This
3280	* is later used when determining whether to group tasks together
3281	*/
3282	if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3283	flags \|= TNF_SHARED;
3284
3285	last_cpupid = page_cpupid_last(page);
3286	page_nid = page_to_nid(page);
3287	target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
3288	pte_unmap_unlock(ptep, ptl);
3289	if (target_nid == -1) {
3290	put_page(page);
3291	goto out;
3292	}
3293
3294	/* Migrate to the requested node */
3295	migrated = migrate_misplaced_page(page, vma, target_nid);
3296	if (migrated) {
3297	page_nid = target_nid;
3298	flags \|= TNF_MIGRATED;
3299	} else
3300	flags \|= TNF_MIGRATE_FAIL;
3301
3302	out:
3303	if (page_nid != -1)
3304	task_numa_fault(last_cpupid, page_nid, 1, flags);
3305	return 0;
3306	}
3307
3308	static int create_huge_pmd(struct mm_struct mm, struct vm_area_struct vma,
3309	unsigned long address, pmd_t *pmd, unsigned int flags)
3310	{
3311	if (vma_is_anonymous(vma))
3312	return do_huge_pmd_anonymous_page(mm, vma, address, pmd, flags);
3313	if (vma->vm_ops->pmd_fault)
3314	return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
3315	return VM_FAULT_FALLBACK;
3316	}
3317
3318	static int wp_huge_pmd(struct mm_struct mm, struct vm_area_struct vma,
3319	unsigned long address, pmd_t *pmd, pmd_t orig_pmd,
3320	unsigned int flags)
3321	{
3322	if (vma_is_anonymous(vma))
3323	return do_huge_pmd_wp_page(mm, vma, address, pmd, orig_pmd);
3324	if (vma->vm_ops->pmd_fault)
3325	return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
3326	return VM_FAULT_FALLBACK;
3327	}
3328
3329	/*
3330	* These routines also need to handle stuff like marking pages dirty
3331	* and/or accessed for architectures that don't do it in hardware (most
3332	* RISC architectures). The early dirtying is also good on the i386.
3333	*
3334	* There is also a hook called "update_mmu_cache()" that architectures
3335	* with external mmu caches can use to update those (ie the Sparc or
3336	* PowerPC hashed page tables that act as extended TLBs).
3337	*
3338	* We enter with non-exclusive mmap_sem (to exclude vma changes,
3339	* but allow concurrent faults), and pte mapped but not yet locked.
3340	* We return with pte unmapped and unlocked.
3341	*
3342	* The mmap_sem may have been released depending on flags and our
3343	* return value. See filemap_fault() and __lock_page_or_retry().
3344	*/
3345	static int handle_pte_fault(struct mm_struct *mm,
3346	struct vm_area_struct *vma, unsigned long address,
3347	pte_t pte, pmd_t pmd, unsigned int flags)
3348	{
3349	pte_t entry;
3350	spinlock_t *ptl;
3351
3352	/*
3353	* some architectures can have larger ptes than wordsize,
3354	* e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and CONFIG_32BIT=y,
3355	* so READ_ONCE or ACCESS_ONCE cannot guarantee atomic accesses.
3356	* The code below just needs a consistent view for the ifs and
3357	* we later double check anyway with the ptl lock held. So here
3358	* a barrier will do.
3359	*/
3360	entry = *pte;
3361	barrier();
3362	if (!pte_present(entry)) {
3363	if (pte_none(entry)) {
3364	if (vma_is_anonymous(vma))
3365	return do_anonymous_page(mm, vma, address,
3366	pte, pmd, flags);
3367	else
3368	return do_fault(mm, vma, address, pte, pmd,
3369	flags, entry);
3370	}
3371	return do_swap_page(mm, vma, address,
3372	pte, pmd, flags, entry);
3373	}
3374
3375	if (pte_protnone(entry))
3376	return do_numa_page(mm, vma, address, entry, pte, pmd);
3377
3378	ptl = pte_lockptr(mm, pmd);
3379	spin_lock(ptl);
3380	if (unlikely(!pte_same(*pte, entry)))
3381	goto unlock;
3382	if (flags & FAULT_FLAG_WRITE) {
3383	if (!pte_write(entry))
3384	return do_wp_page(mm, vma, address,
3385	pte, pmd, ptl, entry);
3386	entry = pte_mkdirty(entry);
3387	}
3388	entry = pte_mkyoung(entry);
3389	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3390	update_mmu_cache(vma, address, pte);
3391	} else {
3392	/*
3393	* This is needed only for protection faults but the arch code
3394	* is not yet telling us if this is a protection fault or not.
3395	* This still avoids useless tlb flushes for .text page faults
3396	* with threads.
3397	*/
3398	if (flags & FAULT_FLAG_WRITE)
3399	flush_tlb_fix_spurious_fault(vma, address);
3400	}
3401	unlock:
3402	pte_unmap_unlock(pte, ptl);
3403	return 0;
3404	}
3405
3406	/*
3407	* By the time we get here, we already hold the mm semaphore
3408	*
3409	* The mmap_sem may have been released depending on flags and our
3410	* return value. See filemap_fault() and __lock_page_or_retry().
3411	*/
3412	static int __handle_mm_fault(struct mm_struct mm, struct vm_area_struct vma,
3413	unsigned long address, unsigned int flags)
3414	{
3415	pgd_t *pgd;
3416	pud_t *pud;
3417	pmd_t *pmd;
3418	pte_t *pte;
3419
3420	if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
3421	flags & FAULT_FLAG_INSTRUCTION,
3422	flags & FAULT_FLAG_REMOTE))
3423	return VM_FAULT_SIGSEGV;
3424
3425	if (unlikely(is_vm_hugetlb_page(vma)))
3426	return hugetlb_fault(mm, vma, address, flags);
3427
3428	pgd = pgd_offset(mm, address);
3429	pud = pud_alloc(mm, pgd, address);
3430	if (!pud)
3431	return VM_FAULT_OOM;
3432	pmd = pmd_alloc(mm, pud, address);
3433	if (!pmd)
3434	return VM_FAULT_OOM;
3435	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3436	int ret = create_huge_pmd(mm, vma, address, pmd, flags);
3437	if (!(ret & VM_FAULT_FALLBACK))
3438	return ret;
3439	} else {
3440	pmd_t orig_pmd = *pmd;
3441	int ret;
3442
3443	barrier();
3444	if (pmd_trans_huge(orig_pmd) \|\| pmd_devmap(orig_pmd)) {
3445	unsigned int dirty = flags & FAULT_FLAG_WRITE;
3446
3447	if (pmd_protnone(orig_pmd))
3448	return do_huge_pmd_numa_page(mm, vma, address,
3449	orig_pmd, pmd);
3450
3451	if (dirty && !pmd_write(orig_pmd)) {
3452	ret = wp_huge_pmd(mm, vma, address, pmd,
3453	orig_pmd, flags);
3454	if (!(ret & VM_FAULT_FALLBACK))
3455	return ret;
3456	} else {
3457	huge_pmd_set_accessed(mm, vma, address, pmd,
3458	orig_pmd, dirty);
3459	return 0;
3460	}
3461	}
3462	}
3463
3464	/*
3465	* Use pte_alloc() instead of pte_alloc_map, because we can't
3466	* run pte_offset_map on the pmd, if an huge pmd could
3467	* materialize from under us from a different thread.
3468	*/
3469	if (unlikely(pte_alloc(mm, pmd, address)))
3470	return VM_FAULT_OOM;
3471	/*
3472	* If a huge pmd materialized under us just retry later. Use
3473	* pmd_trans_unstable() instead of pmd_trans_huge() to ensure the pmd
3474	* didn't become pmd_trans_huge under us and then back to pmd_none, as
3475	* a result of MADV_DONTNEED running immediately after a huge pmd fault
3476	* in a different thread of this mm, in turn leading to a misleading
3477	* pmd_trans_huge() retval. All we have to ensure is that it is a
3478	* regular pmd that we can walk with pte_offset_map() and we can do that
3479	* through an atomic read in C, which is what pmd_trans_unstable()
3480	* provides.
3481	*/
3482	if (unlikely(pmd_trans_unstable(pmd) \|\| pmd_devmap(*pmd)))
3483	return 0;
3484	/*
3485	* A regular pmd is established and it can't morph into a huge pmd
3486	* from under us anymore at this point because we hold the mmap_sem
3487	* read mode and khugepaged takes it in write mode. So now it's
3488	* safe to run pte_offset_map().
3489	*/
3490	pte = pte_offset_map(pmd, address);
3491
3492	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3493	}
3494
3495	/*
3496	* By the time we get here, we already hold the mm semaphore
3497	*
3498	* The mmap_sem may have been released depending on flags and our
3499	* return value. See filemap_fault() and __lock_page_or_retry().
3500	*/
3501	int handle_mm_fault(struct mm_struct mm, struct vm_area_struct vma,
3502	unsigned long address, unsigned int flags)
3503	{
3504	int ret;
3505
3506	__set_current_state(TASK_RUNNING);
3507
3508	count_vm_event(PGFAULT);
3509	mem_cgroup_count_vm_event(mm, PGFAULT);
3510
3511	/* do counter updates before entering really critical section. */
3512	check_sync_rss_stat(current);
3513
3514	/*
3515	* Enable the memcg OOM handling for faults triggered in user
3516	* space. Kernel faults are handled more gracefully.
3517	*/
3518	if (flags & FAULT_FLAG_USER)
3519	mem_cgroup_oom_enable();
3520
3521	ret = __handle_mm_fault(mm, vma, address, flags);
3522
3523	if (flags & FAULT_FLAG_USER) {
3524	mem_cgroup_oom_disable();
3525	/*
3526	* The task may have entered a memcg OOM situation but
3527	* if the allocation error was handled gracefully (no
3528	* VM_FAULT_OOM), there is no need to kill anything.
3529	* Just clean up the OOM state peacefully.
3530	*/
3531	if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3532	mem_cgroup_oom_synchronize(false);
3533	}
3534
3535	return ret;
3536	}
3537	EXPORT_SYMBOL_GPL(handle_mm_fault);
3538
3539	#ifndef __PAGETABLE_PUD_FOLDED
3540	/*
3541	* Allocate page upper directory.
3542	* We've already handled the fast-path in-line.
3543	*/
3544	int __pud_alloc(struct mm_struct mm, pgd_t pgd, unsigned long address)
3545	{
3546	pud_t *new = pud_alloc_one(mm, address);
3547	if (!new)
3548	return -ENOMEM;
3549
3550	smp_wmb(); /* See comment in __pte_alloc */
3551
3552	spin_lock(&mm->page_table_lock);
3553	if (pgd_present(pgd)) / Another has populated it */
3554	pud_free(mm, new);
3555	else
3556	pgd_populate(mm, pgd, new);
3557	spin_unlock(&mm->page_table_lock);
3558	return 0;
3559	}
3560	#endif /* __PAGETABLE_PUD_FOLDED */
3561
3562	#ifndef __PAGETABLE_PMD_FOLDED
3563	/*
3564	* Allocate page middle directory.
3565	* We've already handled the fast-path in-line.
3566	*/
3567	int __pmd_alloc(struct mm_struct mm, pud_t pud, unsigned long address)
3568	{
3569	pmd_t *new = pmd_alloc_one(mm, address);
3570	if (!new)
3571	return -ENOMEM;
3572
3573	smp_wmb(); /* See comment in __pte_alloc */
3574
3575	spin_lock(&mm->page_table_lock);
3576	#ifndef __ARCH_HAS_4LEVEL_HACK
3577	if (!pud_present(*pud)) {
3578	mm_inc_nr_pmds(mm);
3579	pud_populate(mm, pud, new);
3580	} else /* Another has populated it */
3581	pmd_free(mm, new);
3582	#else
3583	if (!pgd_present(*pud)) {
3584	mm_inc_nr_pmds(mm);
3585	pgd_populate(mm, pud, new);
3586	} else /* Another has populated it */
3587	pmd_free(mm, new);
3588	#endif /* __ARCH_HAS_4LEVEL_HACK */
3589	spin_unlock(&mm->page_table_lock);
3590	return 0;
3591	}
3592	#endif /* __PAGETABLE_PMD_FOLDED */
3593
3594	static int __follow_pte(struct mm_struct *mm, unsigned long address,
3595	pte_t ptepp, spinlock_t ptlp)
3596	{
3597	pgd_t *pgd;
3598	pud_t *pud;
3599	pmd_t *pmd;
3600	pte_t *ptep;
3601
3602	pgd = pgd_offset(mm, address);
3603	if (pgd_none(pgd) \|\| unlikely(pgd_bad(pgd)))
3604	goto out;
3605
3606	pud = pud_offset(pgd, address);
3607	if (pud_none(pud) \|\| unlikely(pud_bad(pud)))
3608	goto out;
3609
3610	pmd = pmd_offset(pud, address);
3611	VM_BUG_ON(pmd_trans_huge(*pmd));
3612	if (pmd_none(pmd) \|\| unlikely(pmd_bad(pmd)))
3613	goto out;
3614
3615	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
3616	if (pmd_huge(*pmd))
3617	goto out;
3618
3619	ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3620	if (!ptep)
3621	goto out;
3622	if (!pte_present(*ptep))
3623	goto unlock;
3624	*ptepp = ptep;
3625	return 0;
3626	unlock:
3627	pte_unmap_unlock(ptep, *ptlp);
3628	out:
3629	return -EINVAL;
3630	}
3631
3632	static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3633	pte_t ptepp, spinlock_t ptlp)
3634	{
3635	int res;
3636
3637	/* (void) is needed to make gcc happy */
3638	(void) __cond_lock(*ptlp,
3639	!(res = __follow_pte(mm, address, ptepp, ptlp)));
3640	return res;
3641	}
3642
3643	/**
3644	* follow_pfn - look up PFN at a user virtual address
3645	* @vma: memory mapping
3646	* @address: user virtual address
3647	* @pfn: location to store found PFN
3648	*
3649	* Only IO mappings and raw PFN mappings are allowed.
3650	*
3651	* Returns zero and the pfn at @pfn on success, -ve otherwise.
3652	*/
3653	int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3654	unsigned long *pfn)
3655	{
3656	int ret = -EINVAL;
3657	spinlock_t *ptl;
3658	pte_t *ptep;
3659
3660	if (!(vma->vm_flags & (VM_IO \| VM_PFNMAP)))
3661	return ret;
3662
3663	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3664	if (ret)
3665	return ret;
3666	pfn = pte_pfn(ptep);
3667	pte_unmap_unlock(ptep, ptl);
3668	return 0;
3669	}
3670	EXPORT_SYMBOL(follow_pfn);
3671
3672	#ifdef CONFIG_HAVE_IOREMAP_PROT
3673	int follow_phys(struct vm_area_struct *vma,
3674	unsigned long address, unsigned int flags,
3675	unsigned long prot, resource_size_t phys)
3676	{
3677	int ret = -EINVAL;
3678	pte_t *ptep, pte;
3679	spinlock_t *ptl;
3680
3681	if (!(vma->vm_flags & (VM_IO \| VM_PFNMAP)))
3682	goto out;
3683
3684	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3685	goto out;
3686	pte = *ptep;
3687
3688	if ((flags & FOLL_WRITE) && !pte_write(pte))
3689	goto unlock;
3690
3691	*prot = pgprot_val(pte_pgprot(pte));
3692	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3693
3694	ret = 0;
3695	unlock:
3696	pte_unmap_unlock(ptep, ptl);
3697	out:
3698	return ret;
3699	}
3700
3701	int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3702	void *buf, int len, int write)
3703	{
3704	resource_size_t phys_addr;
3705	unsigned long prot = 0;
3706	void __iomem *maddr;
3707	int offset = addr & (PAGE_SIZE-1);
3708
3709	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3710	return -EINVAL;
3711
3712	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
3713	if (write)
3714	memcpy_toio(maddr + offset, buf, len);
3715	else
3716	memcpy_fromio(buf, maddr + offset, len);
3717	iounmap(maddr);
3718
3719	return len;
3720	}
3721	EXPORT_SYMBOL_GPL(generic_access_phys);
3722	#endif
3723
3724	/*
3725	* Access another process' address space as given in mm. If non-NULL, use the
3726	* given task for page fault accounting.
3727	*/
3728	static int __access_remote_vm(struct task_struct tsk, struct mm_struct mm,
3729	unsigned long addr, void *buf, int len, int write)
3730	{
3731	struct vm_area_struct *vma;
3732	void *old_buf = buf;
3733
3734	down_read(&mm->mmap_sem);
3735	/* ignore errors, just check how much was successfully transferred */
3736	while (len) {
3737	int bytes, ret, offset;
3738	void *maddr;
3739	struct page *page = NULL;
3740
3741	ret = get_user_pages_remote(tsk, mm, addr, 1,
3742	write, 1, &page, &vma);
3743	if (ret <= 0) {
3744	#ifndef CONFIG_HAVE_IOREMAP_PROT
3745	break;
3746	#else
3747	/*
3748	* Check if this is a VM_IO \| VM_PFNMAP VMA, which
3749	* we can access using slightly different code.
3750	*/
3751	vma = find_vma(mm, addr);
3752	if (!vma \|\| vma->vm_start > addr)
3753	break;
3754	if (vma->vm_ops && vma->vm_ops->access)
3755	ret = vma->vm_ops->access(vma, addr, buf,
3756	len, write);
3757	if (ret <= 0)
3758	break;
3759	bytes = ret;
3760	#endif
3761	} else {
3762	bytes = len;
3763	offset = addr & (PAGE_SIZE-1);
3764	if (bytes > PAGE_SIZE-offset)
3765	bytes = PAGE_SIZE-offset;
3766
3767	maddr = kmap(page);
3768	if (write) {
3769	copy_to_user_page(vma, page, addr,
3770	maddr + offset, buf, bytes);
3771	set_page_dirty_lock(page);
3772	} else {
3773	copy_from_user_page(vma, page, addr,
3774	buf, maddr + offset, bytes);
3775	}
3776	kunmap(page);
3777	put_page(page);
3778	}
3779	len -= bytes;
3780	buf += bytes;
3781	addr += bytes;
3782	}
3783	up_read(&mm->mmap_sem);
3784
3785	return buf - old_buf;
3786	}
3787
3788	/**
3789	* access_remote_vm - access another process' address space
3790	* @mm: the mm_struct of the target address space
3791	* @addr: start address to access
3792	* @buf: source or destination buffer
3793	* @len: number of bytes to transfer
3794	* @write: whether the access is a write
3795	*
3796	* The caller must hold a reference on @mm.
3797	*/
3798	int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3799	void *buf, int len, int write)
3800	{
3801	return __access_remote_vm(NULL, mm, addr, buf, len, write);
3802	}
3803
3804	/*
3805	* Access another process' address space.
3806	* Source/target buffer must be kernel space,
3807	* Do not walk the page table directly, use get_user_pages
3808	*/
3809	int access_process_vm(struct task_struct *tsk, unsigned long addr,
3810	void *buf, int len, int write)
3811	{
3812	struct mm_struct *mm;
3813	int ret;
3814
3815	mm = get_task_mm(tsk);
3816	if (!mm)
3817	return 0;
3818
3819	ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3820	mmput(mm);
3821
3822	return ret;
3823	}
3824
3825	/*
3826	* Print the name of a VMA.
3827	*/
3828	void print_vma_addr(char *prefix, unsigned long ip)
3829	{
3830	struct mm_struct *mm = current->mm;
3831	struct vm_area_struct *vma;
3832
3833	/*
3834	* Do not print if we are in atomic
3835	* contexts (in exception stacks, etc.):
3836	*/
3837	if (preempt_count())
3838	return;
3839
3840	down_read(&mm->mmap_sem);
3841	vma = find_vma(mm, ip);
3842	if (vma && vma->vm_file) {
3843	struct file *f = vma->vm_file;
3844	char buf = (char )__get_free_page(GFP_KERNEL);
3845	if (buf) {
3846	char *p;
3847
3848	p = file_path(f, buf, PAGE_SIZE);
3849	if (IS_ERR(p))
3850	p = "?";
3851	printk("%s%s[%lx+%lx]", prefix, kbasename(p),
3852	vma->vm_start,
3853	vma->vm_end - vma->vm_start);
3854	free_page((unsigned long)buf);
3855	}
3856	}
3857	up_read(&mm->mmap_sem);
3858	}
3859
3860	#if defined(CONFIG_PROVE_LOCKING) \|\| defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3861	void __might_fault(const char *file, int line)
3862	{
3863	/*
3864	* Some code (nfs/sunrpc) uses socket ops on kernel memory while
3865	* holding the mmap_sem, this is safe because kernel memory doesn't
3866	* get paged out, therefore we'll never actually fault, and the
3867	* below annotations will generate false positives.
3868	*/
3869	if (segment_eq(get_fs(), KERNEL_DS))
3870	return;
3871	if (pagefault_disabled())
3872	return;
3873	__might_sleep(file, line, 0);
3874	#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3875	if (current->mm)
3876	might_lock_read(&current->mm->mmap_sem);
3877	#endif
3878	}
3879	EXPORT_SYMBOL(__might_fault);
3880	#endif
3881
3882	#if defined(CONFIG_TRANSPARENT_HUGEPAGE) \|\| defined(CONFIG_HUGETLBFS)
3883	static void clear_gigantic_page(struct page *page,
3884	unsigned long addr,
3885	unsigned int pages_per_huge_page)
3886	{
3887	int i;
3888	struct page *p = page;
3889
3890	might_sleep();
3891	for (i = 0; i < pages_per_huge_page;
3892	i++, p = mem_map_next(p, page, i)) {
3893	cond_resched();
3894	clear_user_highpage(p, addr + i * PAGE_SIZE);
3895	}
3896	}
3897	void clear_huge_page(struct page *page,
3898	unsigned long addr, unsigned int pages_per_huge_page)
3899	{
3900	int i;
3901
3902	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3903	clear_gigantic_page(page, addr, pages_per_huge_page);
3904	return;
3905	}
3906
3907	might_sleep();
3908	for (i = 0; i < pages_per_huge_page; i++) {
3909	cond_resched();
3910	clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3911	}
3912	}
3913
3914	static void copy_user_gigantic_page(struct page dst, struct page src,
3915	unsigned long addr,
3916	struct vm_area_struct *vma,
3917	unsigned int pages_per_huge_page)
3918	{
3919	int i;
3920	struct page *dst_base = dst;
3921	struct page *src_base = src;
3922
3923	for (i = 0; i < pages_per_huge_page; ) {
3924	cond_resched();
3925	copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3926
3927	i++;
3928	dst = mem_map_next(dst, dst_base, i);
3929	src = mem_map_next(src, src_base, i);
3930	}
3931	}
3932
3933	void copy_user_huge_page(struct page dst, struct page src,
3934	unsigned long addr, struct vm_area_struct *vma,
3935	unsigned int pages_per_huge_page)
3936	{
3937	int i;
3938
3939	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3940	copy_user_gigantic_page(dst, src, addr, vma,
3941	pages_per_huge_page);
3942	return;
3943	}
3944
3945	might_sleep();
3946	for (i = 0; i < pages_per_huge_page; i++) {
3947	cond_resched();
3948	copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3949	}
3950	}
3951	#endif /* CONFIG_TRANSPARENT_HUGEPAGE \|\| CONFIG_HUGETLBFS */
3952
3953	#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
3954
3955	static struct kmem_cache *page_ptl_cachep;
3956
3957	void __init ptlock_cache_init(void)
3958	{
3959	page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
3960	SLAB_PANIC, NULL);
3961	}
3962
3963	bool ptlock_alloc(struct page *page)
3964	{
3965	spinlock_t *ptl;
3966
3967	ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
3968	if (!ptl)
3969	return false;
3970	page->ptl = ptl;
3971	return true;
3972	}
3973
3974	void ptlock_free(struct page *page)
3975	{
3976	kmem_cache_free(page_ptl_cachep, page->ptl);
3977	}
3978	#endif