xref: /openbmc/linux/mm/memory.c (revision f42b3800)
1 /*
2  *  linux/mm/memory.c
3  *
4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
5  */
6 
7 /*
8  * demand-loading started 01.12.91 - seems it is high on the list of
9  * things wanted, and it should be easy to implement. - Linus
10  */
11 
12 /*
13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14  * pages started 02.12.91, seems to work. - Linus.
15  *
16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17  * would have taken more than the 6M I have free, but it worked well as
18  * far as I could see.
19  *
20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21  */
22 
23 /*
24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
25  * thought has to go into this. Oh, well..
26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
27  *		Found it. Everything seems to work now.
28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
29  */
30 
31 /*
32  * 05.04.94  -  Multi-page memory management added for v1.1.
33  * 		Idea by Alex Bligh (alex@cconcepts.co.uk)
34  *
35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
36  *		(Gerhard.Wichert@pdb.siemens.de)
37  *
38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39  */
40 
41 #include <linux/kernel_stat.h>
42 #include <linux/mm.h>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/rmap.h>
49 #include <linux/module.h>
50 #include <linux/delayacct.h>
51 #include <linux/init.h>
52 #include <linux/writeback.h>
53 #include <linux/memcontrol.h>
54 
55 #include <asm/pgalloc.h>
56 #include <asm/uaccess.h>
57 #include <asm/tlb.h>
58 #include <asm/tlbflush.h>
59 #include <asm/pgtable.h>
60 
61 #include <linux/swapops.h>
62 #include <linux/elf.h>
63 
64 #ifndef CONFIG_NEED_MULTIPLE_NODES
65 /* use the per-pgdat data instead for discontigmem - mbligh */
66 unsigned long max_mapnr;
67 struct page *mem_map;
68 
69 EXPORT_SYMBOL(max_mapnr);
70 EXPORT_SYMBOL(mem_map);
71 #endif
72 
73 unsigned long num_physpages;
74 /*
75  * A number of key systems in x86 including ioremap() rely on the assumption
76  * that high_memory defines the upper bound on direct map memory, then end
77  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
78  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
79  * and ZONE_HIGHMEM.
80  */
81 void * high_memory;
82 
83 EXPORT_SYMBOL(num_physpages);
84 EXPORT_SYMBOL(high_memory);
85 
86 /*
87  * Randomize the address space (stacks, mmaps, brk, etc.).
88  *
89  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
90  *   as ancient (libc5 based) binaries can segfault. )
91  */
92 int randomize_va_space __read_mostly =
93 #ifdef CONFIG_COMPAT_BRK
94 					1;
95 #else
96 					2;
97 #endif
98 
99 static int __init disable_randmaps(char *s)
100 {
101 	randomize_va_space = 0;
102 	return 1;
103 }
104 __setup("norandmaps", disable_randmaps);
105 
106 
107 /*
108  * If a p?d_bad entry is found while walking page tables, report
109  * the error, before resetting entry to p?d_none.  Usually (but
110  * very seldom) called out from the p?d_none_or_clear_bad macros.
111  */
112 
113 void pgd_clear_bad(pgd_t *pgd)
114 {
115 	pgd_ERROR(*pgd);
116 	pgd_clear(pgd);
117 }
118 
119 void pud_clear_bad(pud_t *pud)
120 {
121 	pud_ERROR(*pud);
122 	pud_clear(pud);
123 }
124 
125 void pmd_clear_bad(pmd_t *pmd)
126 {
127 	pmd_ERROR(*pmd);
128 	pmd_clear(pmd);
129 }
130 
131 /*
132  * Note: this doesn't free the actual pages themselves. That
133  * has been handled earlier when unmapping all the memory regions.
134  */
135 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
136 {
137 	pgtable_t token = pmd_pgtable(*pmd);
138 	pmd_clear(pmd);
139 	pte_free_tlb(tlb, token);
140 	tlb->mm->nr_ptes--;
141 }
142 
143 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
144 				unsigned long addr, unsigned long end,
145 				unsigned long floor, unsigned long ceiling)
146 {
147 	pmd_t *pmd;
148 	unsigned long next;
149 	unsigned long start;
150 
151 	start = addr;
152 	pmd = pmd_offset(pud, addr);
153 	do {
154 		next = pmd_addr_end(addr, end);
155 		if (pmd_none_or_clear_bad(pmd))
156 			continue;
157 		free_pte_range(tlb, pmd);
158 	} while (pmd++, addr = next, addr != end);
159 
160 	start &= PUD_MASK;
161 	if (start < floor)
162 		return;
163 	if (ceiling) {
164 		ceiling &= PUD_MASK;
165 		if (!ceiling)
166 			return;
167 	}
168 	if (end - 1 > ceiling - 1)
169 		return;
170 
171 	pmd = pmd_offset(pud, start);
172 	pud_clear(pud);
173 	pmd_free_tlb(tlb, pmd);
174 }
175 
176 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
177 				unsigned long addr, unsigned long end,
178 				unsigned long floor, unsigned long ceiling)
179 {
180 	pud_t *pud;
181 	unsigned long next;
182 	unsigned long start;
183 
184 	start = addr;
185 	pud = pud_offset(pgd, addr);
186 	do {
187 		next = pud_addr_end(addr, end);
188 		if (pud_none_or_clear_bad(pud))
189 			continue;
190 		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
191 	} while (pud++, addr = next, addr != end);
192 
193 	start &= PGDIR_MASK;
194 	if (start < floor)
195 		return;
196 	if (ceiling) {
197 		ceiling &= PGDIR_MASK;
198 		if (!ceiling)
199 			return;
200 	}
201 	if (end - 1 > ceiling - 1)
202 		return;
203 
204 	pud = pud_offset(pgd, start);
205 	pgd_clear(pgd);
206 	pud_free_tlb(tlb, pud);
207 }
208 
209 /*
210  * This function frees user-level page tables of a process.
211  *
212  * Must be called with pagetable lock held.
213  */
214 void free_pgd_range(struct mmu_gather **tlb,
215 			unsigned long addr, unsigned long end,
216 			unsigned long floor, unsigned long ceiling)
217 {
218 	pgd_t *pgd;
219 	unsigned long next;
220 	unsigned long start;
221 
222 	/*
223 	 * The next few lines have given us lots of grief...
224 	 *
225 	 * Why are we testing PMD* at this top level?  Because often
226 	 * there will be no work to do at all, and we'd prefer not to
227 	 * go all the way down to the bottom just to discover that.
228 	 *
229 	 * Why all these "- 1"s?  Because 0 represents both the bottom
230 	 * of the address space and the top of it (using -1 for the
231 	 * top wouldn't help much: the masks would do the wrong thing).
232 	 * The rule is that addr 0 and floor 0 refer to the bottom of
233 	 * the address space, but end 0 and ceiling 0 refer to the top
234 	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
235 	 * that end 0 case should be mythical).
236 	 *
237 	 * Wherever addr is brought up or ceiling brought down, we must
238 	 * be careful to reject "the opposite 0" before it confuses the
239 	 * subsequent tests.  But what about where end is brought down
240 	 * by PMD_SIZE below? no, end can't go down to 0 there.
241 	 *
242 	 * Whereas we round start (addr) and ceiling down, by different
243 	 * masks at different levels, in order to test whether a table
244 	 * now has no other vmas using it, so can be freed, we don't
245 	 * bother to round floor or end up - the tests don't need that.
246 	 */
247 
248 	addr &= PMD_MASK;
249 	if (addr < floor) {
250 		addr += PMD_SIZE;
251 		if (!addr)
252 			return;
253 	}
254 	if (ceiling) {
255 		ceiling &= PMD_MASK;
256 		if (!ceiling)
257 			return;
258 	}
259 	if (end - 1 > ceiling - 1)
260 		end -= PMD_SIZE;
261 	if (addr > end - 1)
262 		return;
263 
264 	start = addr;
265 	pgd = pgd_offset((*tlb)->mm, addr);
266 	do {
267 		next = pgd_addr_end(addr, end);
268 		if (pgd_none_or_clear_bad(pgd))
269 			continue;
270 		free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
271 	} while (pgd++, addr = next, addr != end);
272 }
273 
274 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
275 		unsigned long floor, unsigned long ceiling)
276 {
277 	while (vma) {
278 		struct vm_area_struct *next = vma->vm_next;
279 		unsigned long addr = vma->vm_start;
280 
281 		/*
282 		 * Hide vma from rmap and vmtruncate before freeing pgtables
283 		 */
284 		anon_vma_unlink(vma);
285 		unlink_file_vma(vma);
286 
287 		if (is_vm_hugetlb_page(vma)) {
288 			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
289 				floor, next? next->vm_start: ceiling);
290 		} else {
291 			/*
292 			 * Optimization: gather nearby vmas into one call down
293 			 */
294 			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
295 			       && !is_vm_hugetlb_page(next)) {
296 				vma = next;
297 				next = vma->vm_next;
298 				anon_vma_unlink(vma);
299 				unlink_file_vma(vma);
300 			}
301 			free_pgd_range(tlb, addr, vma->vm_end,
302 				floor, next? next->vm_start: ceiling);
303 		}
304 		vma = next;
305 	}
306 }
307 
308 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
309 {
310 	pgtable_t new = pte_alloc_one(mm, address);
311 	if (!new)
312 		return -ENOMEM;
313 
314 	spin_lock(&mm->page_table_lock);
315 	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
316 		mm->nr_ptes++;
317 		pmd_populate(mm, pmd, new);
318 		new = NULL;
319 	}
320 	spin_unlock(&mm->page_table_lock);
321 	if (new)
322 		pte_free(mm, new);
323 	return 0;
324 }
325 
326 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
327 {
328 	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
329 	if (!new)
330 		return -ENOMEM;
331 
332 	spin_lock(&init_mm.page_table_lock);
333 	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
334 		pmd_populate_kernel(&init_mm, pmd, new);
335 		new = NULL;
336 	}
337 	spin_unlock(&init_mm.page_table_lock);
338 	if (new)
339 		pte_free_kernel(&init_mm, new);
340 	return 0;
341 }
342 
343 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
344 {
345 	if (file_rss)
346 		add_mm_counter(mm, file_rss, file_rss);
347 	if (anon_rss)
348 		add_mm_counter(mm, anon_rss, anon_rss);
349 }
350 
351 /*
352  * This function is called to print an error when a bad pte
353  * is found. For example, we might have a PFN-mapped pte in
354  * a region that doesn't allow it.
355  *
356  * The calling function must still handle the error.
357  */
358 void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
359 {
360 	printk(KERN_ERR "Bad pte = %08llx, process = %s, "
361 			"vm_flags = %lx, vaddr = %lx\n",
362 		(long long)pte_val(pte),
363 		(vma->vm_mm == current->mm ? current->comm : "???"),
364 		vma->vm_flags, vaddr);
365 	dump_stack();
366 }
367 
368 static inline int is_cow_mapping(unsigned int flags)
369 {
370 	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
371 }
372 
373 /*
374  * This function gets the "struct page" associated with a pte.
375  *
376  * NOTE! Some mappings do not have "struct pages". A raw PFN mapping
377  * will have each page table entry just pointing to a raw page frame
378  * number, and as far as the VM layer is concerned, those do not have
379  * pages associated with them - even if the PFN might point to memory
380  * that otherwise is perfectly fine and has a "struct page".
381  *
382  * The way we recognize those mappings is through the rules set up
383  * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set,
384  * and the vm_pgoff will point to the first PFN mapped: thus every
385  * page that is a raw mapping will always honor the rule
386  *
387  *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
388  *
389  * and if that isn't true, the page has been COW'ed (in which case it
390  * _does_ have a "struct page" associated with it even if it is in a
391  * VM_PFNMAP range).
392  */
393 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte)
394 {
395 	unsigned long pfn = pte_pfn(pte);
396 
397 	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
398 		unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
399 		if (pfn == vma->vm_pgoff + off)
400 			return NULL;
401 		if (!is_cow_mapping(vma->vm_flags))
402 			return NULL;
403 	}
404 
405 #ifdef CONFIG_DEBUG_VM
406 	/*
407 	 * Add some anal sanity checks for now. Eventually,
408 	 * we should just do "return pfn_to_page(pfn)", but
409 	 * in the meantime we check that we get a valid pfn,
410 	 * and that the resulting page looks ok.
411 	 */
412 	if (unlikely(!pfn_valid(pfn))) {
413 		print_bad_pte(vma, pte, addr);
414 		return NULL;
415 	}
416 #endif
417 
418 	/*
419 	 * NOTE! We still have PageReserved() pages in the page
420 	 * tables.
421 	 *
422 	 * The PAGE_ZERO() pages and various VDSO mappings can
423 	 * cause them to exist.
424 	 */
425 	return pfn_to_page(pfn);
426 }
427 
428 /*
429  * copy one vm_area from one task to the other. Assumes the page tables
430  * already present in the new task to be cleared in the whole range
431  * covered by this vma.
432  */
433 
434 static inline void
435 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
436 		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
437 		unsigned long addr, int *rss)
438 {
439 	unsigned long vm_flags = vma->vm_flags;
440 	pte_t pte = *src_pte;
441 	struct page *page;
442 
443 	/* pte contains position in swap or file, so copy. */
444 	if (unlikely(!pte_present(pte))) {
445 		if (!pte_file(pte)) {
446 			swp_entry_t entry = pte_to_swp_entry(pte);
447 
448 			swap_duplicate(entry);
449 			/* make sure dst_mm is on swapoff's mmlist. */
450 			if (unlikely(list_empty(&dst_mm->mmlist))) {
451 				spin_lock(&mmlist_lock);
452 				if (list_empty(&dst_mm->mmlist))
453 					list_add(&dst_mm->mmlist,
454 						 &src_mm->mmlist);
455 				spin_unlock(&mmlist_lock);
456 			}
457 			if (is_write_migration_entry(entry) &&
458 					is_cow_mapping(vm_flags)) {
459 				/*
460 				 * COW mappings require pages in both parent
461 				 * and child to be set to read.
462 				 */
463 				make_migration_entry_read(&entry);
464 				pte = swp_entry_to_pte(entry);
465 				set_pte_at(src_mm, addr, src_pte, pte);
466 			}
467 		}
468 		goto out_set_pte;
469 	}
470 
471 	/*
472 	 * If it's a COW mapping, write protect it both
473 	 * in the parent and the child
474 	 */
475 	if (is_cow_mapping(vm_flags)) {
476 		ptep_set_wrprotect(src_mm, addr, src_pte);
477 		pte = pte_wrprotect(pte);
478 	}
479 
480 	/*
481 	 * If it's a shared mapping, mark it clean in
482 	 * the child
483 	 */
484 	if (vm_flags & VM_SHARED)
485 		pte = pte_mkclean(pte);
486 	pte = pte_mkold(pte);
487 
488 	page = vm_normal_page(vma, addr, pte);
489 	if (page) {
490 		get_page(page);
491 		page_dup_rmap(page, vma, addr);
492 		rss[!!PageAnon(page)]++;
493 	}
494 
495 out_set_pte:
496 	set_pte_at(dst_mm, addr, dst_pte, pte);
497 }
498 
499 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
500 		pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
501 		unsigned long addr, unsigned long end)
502 {
503 	pte_t *src_pte, *dst_pte;
504 	spinlock_t *src_ptl, *dst_ptl;
505 	int progress = 0;
506 	int rss[2];
507 
508 again:
509 	rss[1] = rss[0] = 0;
510 	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
511 	if (!dst_pte)
512 		return -ENOMEM;
513 	src_pte = pte_offset_map_nested(src_pmd, addr);
514 	src_ptl = pte_lockptr(src_mm, src_pmd);
515 	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
516 	arch_enter_lazy_mmu_mode();
517 
518 	do {
519 		/*
520 		 * We are holding two locks at this point - either of them
521 		 * could generate latencies in another task on another CPU.
522 		 */
523 		if (progress >= 32) {
524 			progress = 0;
525 			if (need_resched() ||
526 			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
527 				break;
528 		}
529 		if (pte_none(*src_pte)) {
530 			progress++;
531 			continue;
532 		}
533 		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
534 		progress += 8;
535 	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
536 
537 	arch_leave_lazy_mmu_mode();
538 	spin_unlock(src_ptl);
539 	pte_unmap_nested(src_pte - 1);
540 	add_mm_rss(dst_mm, rss[0], rss[1]);
541 	pte_unmap_unlock(dst_pte - 1, dst_ptl);
542 	cond_resched();
543 	if (addr != end)
544 		goto again;
545 	return 0;
546 }
547 
548 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
549 		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
550 		unsigned long addr, unsigned long end)
551 {
552 	pmd_t *src_pmd, *dst_pmd;
553 	unsigned long next;
554 
555 	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
556 	if (!dst_pmd)
557 		return -ENOMEM;
558 	src_pmd = pmd_offset(src_pud, addr);
559 	do {
560 		next = pmd_addr_end(addr, end);
561 		if (pmd_none_or_clear_bad(src_pmd))
562 			continue;
563 		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
564 						vma, addr, next))
565 			return -ENOMEM;
566 	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
567 	return 0;
568 }
569 
570 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
571 		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
572 		unsigned long addr, unsigned long end)
573 {
574 	pud_t *src_pud, *dst_pud;
575 	unsigned long next;
576 
577 	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
578 	if (!dst_pud)
579 		return -ENOMEM;
580 	src_pud = pud_offset(src_pgd, addr);
581 	do {
582 		next = pud_addr_end(addr, end);
583 		if (pud_none_or_clear_bad(src_pud))
584 			continue;
585 		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
586 						vma, addr, next))
587 			return -ENOMEM;
588 	} while (dst_pud++, src_pud++, addr = next, addr != end);
589 	return 0;
590 }
591 
592 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
593 		struct vm_area_struct *vma)
594 {
595 	pgd_t *src_pgd, *dst_pgd;
596 	unsigned long next;
597 	unsigned long addr = vma->vm_start;
598 	unsigned long end = vma->vm_end;
599 
600 	/*
601 	 * Don't copy ptes where a page fault will fill them correctly.
602 	 * Fork becomes much lighter when there are big shared or private
603 	 * readonly mappings. The tradeoff is that copy_page_range is more
604 	 * efficient than faulting.
605 	 */
606 	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
607 		if (!vma->anon_vma)
608 			return 0;
609 	}
610 
611 	if (is_vm_hugetlb_page(vma))
612 		return copy_hugetlb_page_range(dst_mm, src_mm, vma);
613 
614 	dst_pgd = pgd_offset(dst_mm, addr);
615 	src_pgd = pgd_offset(src_mm, addr);
616 	do {
617 		next = pgd_addr_end(addr, end);
618 		if (pgd_none_or_clear_bad(src_pgd))
619 			continue;
620 		if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
621 						vma, addr, next))
622 			return -ENOMEM;
623 	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
624 	return 0;
625 }
626 
627 static unsigned long zap_pte_range(struct mmu_gather *tlb,
628 				struct vm_area_struct *vma, pmd_t *pmd,
629 				unsigned long addr, unsigned long end,
630 				long *zap_work, struct zap_details *details)
631 {
632 	struct mm_struct *mm = tlb->mm;
633 	pte_t *pte;
634 	spinlock_t *ptl;
635 	int file_rss = 0;
636 	int anon_rss = 0;
637 
638 	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
639 	arch_enter_lazy_mmu_mode();
640 	do {
641 		pte_t ptent = *pte;
642 		if (pte_none(ptent)) {
643 			(*zap_work)--;
644 			continue;
645 		}
646 
647 		(*zap_work) -= PAGE_SIZE;
648 
649 		if (pte_present(ptent)) {
650 			struct page *page;
651 
652 			page = vm_normal_page(vma, addr, ptent);
653 			if (unlikely(details) && page) {
654 				/*
655 				 * unmap_shared_mapping_pages() wants to
656 				 * invalidate cache without truncating:
657 				 * unmap shared but keep private pages.
658 				 */
659 				if (details->check_mapping &&
660 				    details->check_mapping != page->mapping)
661 					continue;
662 				/*
663 				 * Each page->index must be checked when
664 				 * invalidating or truncating nonlinear.
665 				 */
666 				if (details->nonlinear_vma &&
667 				    (page->index < details->first_index ||
668 				     page->index > details->last_index))
669 					continue;
670 			}
671 			ptent = ptep_get_and_clear_full(mm, addr, pte,
672 							tlb->fullmm);
673 			tlb_remove_tlb_entry(tlb, pte, addr);
674 			if (unlikely(!page))
675 				continue;
676 			if (unlikely(details) && details->nonlinear_vma
677 			    && linear_page_index(details->nonlinear_vma,
678 						addr) != page->index)
679 				set_pte_at(mm, addr, pte,
680 					   pgoff_to_pte(page->index));
681 			if (PageAnon(page))
682 				anon_rss--;
683 			else {
684 				if (pte_dirty(ptent))
685 					set_page_dirty(page);
686 				if (pte_young(ptent))
687 					SetPageReferenced(page);
688 				file_rss--;
689 			}
690 			page_remove_rmap(page, vma);
691 			tlb_remove_page(tlb, page);
692 			continue;
693 		}
694 		/*
695 		 * If details->check_mapping, we leave swap entries;
696 		 * if details->nonlinear_vma, we leave file entries.
697 		 */
698 		if (unlikely(details))
699 			continue;
700 		if (!pte_file(ptent))
701 			free_swap_and_cache(pte_to_swp_entry(ptent));
702 		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
703 	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
704 
705 	add_mm_rss(mm, file_rss, anon_rss);
706 	arch_leave_lazy_mmu_mode();
707 	pte_unmap_unlock(pte - 1, ptl);
708 
709 	return addr;
710 }
711 
712 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
713 				struct vm_area_struct *vma, pud_t *pud,
714 				unsigned long addr, unsigned long end,
715 				long *zap_work, struct zap_details *details)
716 {
717 	pmd_t *pmd;
718 	unsigned long next;
719 
720 	pmd = pmd_offset(pud, addr);
721 	do {
722 		next = pmd_addr_end(addr, end);
723 		if (pmd_none_or_clear_bad(pmd)) {
724 			(*zap_work)--;
725 			continue;
726 		}
727 		next = zap_pte_range(tlb, vma, pmd, addr, next,
728 						zap_work, details);
729 	} while (pmd++, addr = next, (addr != end && *zap_work > 0));
730 
731 	return addr;
732 }
733 
734 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
735 				struct vm_area_struct *vma, pgd_t *pgd,
736 				unsigned long addr, unsigned long end,
737 				long *zap_work, struct zap_details *details)
738 {
739 	pud_t *pud;
740 	unsigned long next;
741 
742 	pud = pud_offset(pgd, addr);
743 	do {
744 		next = pud_addr_end(addr, end);
745 		if (pud_none_or_clear_bad(pud)) {
746 			(*zap_work)--;
747 			continue;
748 		}
749 		next = zap_pmd_range(tlb, vma, pud, addr, next,
750 						zap_work, details);
751 	} while (pud++, addr = next, (addr != end && *zap_work > 0));
752 
753 	return addr;
754 }
755 
756 static unsigned long unmap_page_range(struct mmu_gather *tlb,
757 				struct vm_area_struct *vma,
758 				unsigned long addr, unsigned long end,
759 				long *zap_work, struct zap_details *details)
760 {
761 	pgd_t *pgd;
762 	unsigned long next;
763 
764 	if (details && !details->check_mapping && !details->nonlinear_vma)
765 		details = NULL;
766 
767 	BUG_ON(addr >= end);
768 	tlb_start_vma(tlb, vma);
769 	pgd = pgd_offset(vma->vm_mm, addr);
770 	do {
771 		next = pgd_addr_end(addr, end);
772 		if (pgd_none_or_clear_bad(pgd)) {
773 			(*zap_work)--;
774 			continue;
775 		}
776 		next = zap_pud_range(tlb, vma, pgd, addr, next,
777 						zap_work, details);
778 	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
779 	tlb_end_vma(tlb, vma);
780 
781 	return addr;
782 }
783 
784 #ifdef CONFIG_PREEMPT
785 # define ZAP_BLOCK_SIZE	(8 * PAGE_SIZE)
786 #else
787 /* No preempt: go for improved straight-line efficiency */
788 # define ZAP_BLOCK_SIZE	(1024 * PAGE_SIZE)
789 #endif
790 
791 /**
792  * unmap_vmas - unmap a range of memory covered by a list of vma's
793  * @tlbp: address of the caller's struct mmu_gather
794  * @vma: the starting vma
795  * @start_addr: virtual address at which to start unmapping
796  * @end_addr: virtual address at which to end unmapping
797  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
798  * @details: details of nonlinear truncation or shared cache invalidation
799  *
800  * Returns the end address of the unmapping (restart addr if interrupted).
801  *
802  * Unmap all pages in the vma list.
803  *
804  * We aim to not hold locks for too long (for scheduling latency reasons).
805  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
806  * return the ending mmu_gather to the caller.
807  *
808  * Only addresses between `start' and `end' will be unmapped.
809  *
810  * The VMA list must be sorted in ascending virtual address order.
811  *
812  * unmap_vmas() assumes that the caller will flush the whole unmapped address
813  * range after unmap_vmas() returns.  So the only responsibility here is to
814  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
815  * drops the lock and schedules.
816  */
817 unsigned long unmap_vmas(struct mmu_gather **tlbp,
818 		struct vm_area_struct *vma, unsigned long start_addr,
819 		unsigned long end_addr, unsigned long *nr_accounted,
820 		struct zap_details *details)
821 {
822 	long zap_work = ZAP_BLOCK_SIZE;
823 	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
824 	int tlb_start_valid = 0;
825 	unsigned long start = start_addr;
826 	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
827 	int fullmm = (*tlbp)->fullmm;
828 
829 	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
830 		unsigned long end;
831 
832 		start = max(vma->vm_start, start_addr);
833 		if (start >= vma->vm_end)
834 			continue;
835 		end = min(vma->vm_end, end_addr);
836 		if (end <= vma->vm_start)
837 			continue;
838 
839 		if (vma->vm_flags & VM_ACCOUNT)
840 			*nr_accounted += (end - start) >> PAGE_SHIFT;
841 
842 		while (start != end) {
843 			if (!tlb_start_valid) {
844 				tlb_start = start;
845 				tlb_start_valid = 1;
846 			}
847 
848 			if (unlikely(is_vm_hugetlb_page(vma))) {
849 				unmap_hugepage_range(vma, start, end);
850 				zap_work -= (end - start) /
851 						(HPAGE_SIZE / PAGE_SIZE);
852 				start = end;
853 			} else
854 				start = unmap_page_range(*tlbp, vma,
855 						start, end, &zap_work, details);
856 
857 			if (zap_work > 0) {
858 				BUG_ON(start != end);
859 				break;
860 			}
861 
862 			tlb_finish_mmu(*tlbp, tlb_start, start);
863 
864 			if (need_resched() ||
865 				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
866 				if (i_mmap_lock) {
867 					*tlbp = NULL;
868 					goto out;
869 				}
870 				cond_resched();
871 			}
872 
873 			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
874 			tlb_start_valid = 0;
875 			zap_work = ZAP_BLOCK_SIZE;
876 		}
877 	}
878 out:
879 	return start;	/* which is now the end (or restart) address */
880 }
881 
882 /**
883  * zap_page_range - remove user pages in a given range
884  * @vma: vm_area_struct holding the applicable pages
885  * @address: starting address of pages to zap
886  * @size: number of bytes to zap
887  * @details: details of nonlinear truncation or shared cache invalidation
888  */
889 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
890 		unsigned long size, struct zap_details *details)
891 {
892 	struct mm_struct *mm = vma->vm_mm;
893 	struct mmu_gather *tlb;
894 	unsigned long end = address + size;
895 	unsigned long nr_accounted = 0;
896 
897 	lru_add_drain();
898 	tlb = tlb_gather_mmu(mm, 0);
899 	update_hiwater_rss(mm);
900 	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
901 	if (tlb)
902 		tlb_finish_mmu(tlb, address, end);
903 	return end;
904 }
905 
906 /*
907  * Do a quick page-table lookup for a single page.
908  */
909 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
910 			unsigned int flags)
911 {
912 	pgd_t *pgd;
913 	pud_t *pud;
914 	pmd_t *pmd;
915 	pte_t *ptep, pte;
916 	spinlock_t *ptl;
917 	struct page *page;
918 	struct mm_struct *mm = vma->vm_mm;
919 
920 	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
921 	if (!IS_ERR(page)) {
922 		BUG_ON(flags & FOLL_GET);
923 		goto out;
924 	}
925 
926 	page = NULL;
927 	pgd = pgd_offset(mm, address);
928 	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
929 		goto no_page_table;
930 
931 	pud = pud_offset(pgd, address);
932 	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
933 		goto no_page_table;
934 
935 	pmd = pmd_offset(pud, address);
936 	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
937 		goto no_page_table;
938 
939 	if (pmd_huge(*pmd)) {
940 		BUG_ON(flags & FOLL_GET);
941 		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
942 		goto out;
943 	}
944 
945 	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
946 	if (!ptep)
947 		goto out;
948 
949 	pte = *ptep;
950 	if (!pte_present(pte))
951 		goto unlock;
952 	if ((flags & FOLL_WRITE) && !pte_write(pte))
953 		goto unlock;
954 	page = vm_normal_page(vma, address, pte);
955 	if (unlikely(!page))
956 		goto unlock;
957 
958 	if (flags & FOLL_GET)
959 		get_page(page);
960 	if (flags & FOLL_TOUCH) {
961 		if ((flags & FOLL_WRITE) &&
962 		    !pte_dirty(pte) && !PageDirty(page))
963 			set_page_dirty(page);
964 		mark_page_accessed(page);
965 	}
966 unlock:
967 	pte_unmap_unlock(ptep, ptl);
968 out:
969 	return page;
970 
971 no_page_table:
972 	/*
973 	 * When core dumping an enormous anonymous area that nobody
974 	 * has touched so far, we don't want to allocate page tables.
975 	 */
976 	if (flags & FOLL_ANON) {
977 		page = ZERO_PAGE(0);
978 		if (flags & FOLL_GET)
979 			get_page(page);
980 		BUG_ON(flags & FOLL_WRITE);
981 	}
982 	return page;
983 }
984 
985 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
986 		unsigned long start, int len, int write, int force,
987 		struct page **pages, struct vm_area_struct **vmas)
988 {
989 	int i;
990 	unsigned int vm_flags;
991 
992 	if (len <= 0)
993 		return 0;
994 	/*
995 	 * Require read or write permissions.
996 	 * If 'force' is set, we only require the "MAY" flags.
997 	 */
998 	vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
999 	vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1000 	i = 0;
1001 
1002 	do {
1003 		struct vm_area_struct *vma;
1004 		unsigned int foll_flags;
1005 
1006 		vma = find_extend_vma(mm, start);
1007 		if (!vma && in_gate_area(tsk, start)) {
1008 			unsigned long pg = start & PAGE_MASK;
1009 			struct vm_area_struct *gate_vma = get_gate_vma(tsk);
1010 			pgd_t *pgd;
1011 			pud_t *pud;
1012 			pmd_t *pmd;
1013 			pte_t *pte;
1014 			if (write) /* user gate pages are read-only */
1015 				return i ? : -EFAULT;
1016 			if (pg > TASK_SIZE)
1017 				pgd = pgd_offset_k(pg);
1018 			else
1019 				pgd = pgd_offset_gate(mm, pg);
1020 			BUG_ON(pgd_none(*pgd));
1021 			pud = pud_offset(pgd, pg);
1022 			BUG_ON(pud_none(*pud));
1023 			pmd = pmd_offset(pud, pg);
1024 			if (pmd_none(*pmd))
1025 				return i ? : -EFAULT;
1026 			pte = pte_offset_map(pmd, pg);
1027 			if (pte_none(*pte)) {
1028 				pte_unmap(pte);
1029 				return i ? : -EFAULT;
1030 			}
1031 			if (pages) {
1032 				struct page *page = vm_normal_page(gate_vma, start, *pte);
1033 				pages[i] = page;
1034 				if (page)
1035 					get_page(page);
1036 			}
1037 			pte_unmap(pte);
1038 			if (vmas)
1039 				vmas[i] = gate_vma;
1040 			i++;
1041 			start += PAGE_SIZE;
1042 			len--;
1043 			continue;
1044 		}
1045 
1046 		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
1047 				|| !(vm_flags & vma->vm_flags))
1048 			return i ? : -EFAULT;
1049 
1050 		if (is_vm_hugetlb_page(vma)) {
1051 			i = follow_hugetlb_page(mm, vma, pages, vmas,
1052 						&start, &len, i, write);
1053 			continue;
1054 		}
1055 
1056 		foll_flags = FOLL_TOUCH;
1057 		if (pages)
1058 			foll_flags |= FOLL_GET;
1059 		if (!write && !(vma->vm_flags & VM_LOCKED) &&
1060 		    (!vma->vm_ops || (!vma->vm_ops->nopage &&
1061 					!vma->vm_ops->fault)))
1062 			foll_flags |= FOLL_ANON;
1063 
1064 		do {
1065 			struct page *page;
1066 
1067 			/*
1068 			 * If tsk is ooming, cut off its access to large memory
1069 			 * allocations. It has a pending SIGKILL, but it can't
1070 			 * be processed until returning to user space.
1071 			 */
1072 			if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
1073 				return -ENOMEM;
1074 
1075 			if (write)
1076 				foll_flags |= FOLL_WRITE;
1077 
1078 			cond_resched();
1079 			while (!(page = follow_page(vma, start, foll_flags))) {
1080 				int ret;
1081 				ret = handle_mm_fault(mm, vma, start,
1082 						foll_flags & FOLL_WRITE);
1083 				if (ret & VM_FAULT_ERROR) {
1084 					if (ret & VM_FAULT_OOM)
1085 						return i ? i : -ENOMEM;
1086 					else if (ret & VM_FAULT_SIGBUS)
1087 						return i ? i : -EFAULT;
1088 					BUG();
1089 				}
1090 				if (ret & VM_FAULT_MAJOR)
1091 					tsk->maj_flt++;
1092 				else
1093 					tsk->min_flt++;
1094 
1095 				/*
1096 				 * The VM_FAULT_WRITE bit tells us that
1097 				 * do_wp_page has broken COW when necessary,
1098 				 * even if maybe_mkwrite decided not to set
1099 				 * pte_write. We can thus safely do subsequent
1100 				 * page lookups as if they were reads.
1101 				 */
1102 				if (ret & VM_FAULT_WRITE)
1103 					foll_flags &= ~FOLL_WRITE;
1104 
1105 				cond_resched();
1106 			}
1107 			if (pages) {
1108 				pages[i] = page;
1109 
1110 				flush_anon_page(vma, page, start);
1111 				flush_dcache_page(page);
1112 			}
1113 			if (vmas)
1114 				vmas[i] = vma;
1115 			i++;
1116 			start += PAGE_SIZE;
1117 			len--;
1118 		} while (len && start < vma->vm_end);
1119 	} while (len);
1120 	return i;
1121 }
1122 EXPORT_SYMBOL(get_user_pages);
1123 
1124 pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
1125 			spinlock_t **ptl)
1126 {
1127 	pgd_t * pgd = pgd_offset(mm, addr);
1128 	pud_t * pud = pud_alloc(mm, pgd, addr);
1129 	if (pud) {
1130 		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1131 		if (pmd)
1132 			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1133 	}
1134 	return NULL;
1135 }
1136 
1137 /*
1138  * This is the old fallback for page remapping.
1139  *
1140  * For historical reasons, it only allows reserved pages. Only
1141  * old drivers should use this, and they needed to mark their
1142  * pages reserved for the old functions anyway.
1143  */
1144 static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot)
1145 {
1146 	int retval;
1147 	pte_t *pte;
1148 	spinlock_t *ptl;
1149 
1150 	retval = mem_cgroup_charge(page, mm, GFP_KERNEL);
1151 	if (retval)
1152 		goto out;
1153 
1154 	retval = -EINVAL;
1155 	if (PageAnon(page))
1156 		goto out_uncharge;
1157 	retval = -ENOMEM;
1158 	flush_dcache_page(page);
1159 	pte = get_locked_pte(mm, addr, &ptl);
1160 	if (!pte)
1161 		goto out_uncharge;
1162 	retval = -EBUSY;
1163 	if (!pte_none(*pte))
1164 		goto out_unlock;
1165 
1166 	/* Ok, finally just insert the thing.. */
1167 	get_page(page);
1168 	inc_mm_counter(mm, file_rss);
1169 	page_add_file_rmap(page);
1170 	set_pte_at(mm, addr, pte, mk_pte(page, prot));
1171 
1172 	retval = 0;
1173 	pte_unmap_unlock(pte, ptl);
1174 	return retval;
1175 out_unlock:
1176 	pte_unmap_unlock(pte, ptl);
1177 out_uncharge:
1178 	mem_cgroup_uncharge_page(page);
1179 out:
1180 	return retval;
1181 }
1182 
1183 /**
1184  * vm_insert_page - insert single page into user vma
1185  * @vma: user vma to map to
1186  * @addr: target user address of this page
1187  * @page: source kernel page
1188  *
1189  * This allows drivers to insert individual pages they've allocated
1190  * into a user vma.
1191  *
1192  * The page has to be a nice clean _individual_ kernel allocation.
1193  * If you allocate a compound page, you need to have marked it as
1194  * such (__GFP_COMP), or manually just split the page up yourself
1195  * (see split_page()).
1196  *
1197  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1198  * took an arbitrary page protection parameter. This doesn't allow
1199  * that. Your vma protection will have to be set up correctly, which
1200  * means that if you want a shared writable mapping, you'd better
1201  * ask for a shared writable mapping!
1202  *
1203  * The page does not need to be reserved.
1204  */
1205 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page)
1206 {
1207 	if (addr < vma->vm_start || addr >= vma->vm_end)
1208 		return -EFAULT;
1209 	if (!page_count(page))
1210 		return -EINVAL;
1211 	vma->vm_flags |= VM_INSERTPAGE;
1212 	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
1213 }
1214 EXPORT_SYMBOL(vm_insert_page);
1215 
1216 /**
1217  * vm_insert_pfn - insert single pfn into user vma
1218  * @vma: user vma to map to
1219  * @addr: target user address of this page
1220  * @pfn: source kernel pfn
1221  *
1222  * Similar to vm_inert_page, this allows drivers to insert individual pages
1223  * they've allocated into a user vma. Same comments apply.
1224  *
1225  * This function should only be called from a vm_ops->fault handler, and
1226  * in that case the handler should return NULL.
1227  */
1228 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1229 		unsigned long pfn)
1230 {
1231 	struct mm_struct *mm = vma->vm_mm;
1232 	int retval;
1233 	pte_t *pte, entry;
1234 	spinlock_t *ptl;
1235 
1236 	BUG_ON(!(vma->vm_flags & VM_PFNMAP));
1237 	BUG_ON(is_cow_mapping(vma->vm_flags));
1238 
1239 	retval = -ENOMEM;
1240 	pte = get_locked_pte(mm, addr, &ptl);
1241 	if (!pte)
1242 		goto out;
1243 	retval = -EBUSY;
1244 	if (!pte_none(*pte))
1245 		goto out_unlock;
1246 
1247 	/* Ok, finally just insert the thing.. */
1248 	entry = pfn_pte(pfn, vma->vm_page_prot);
1249 	set_pte_at(mm, addr, pte, entry);
1250 	update_mmu_cache(vma, addr, entry);
1251 
1252 	retval = 0;
1253 out_unlock:
1254 	pte_unmap_unlock(pte, ptl);
1255 
1256 out:
1257 	return retval;
1258 }
1259 EXPORT_SYMBOL(vm_insert_pfn);
1260 
1261 /*
1262  * maps a range of physical memory into the requested pages. the old
1263  * mappings are removed. any references to nonexistent pages results
1264  * in null mappings (currently treated as "copy-on-access")
1265  */
1266 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1267 			unsigned long addr, unsigned long end,
1268 			unsigned long pfn, pgprot_t prot)
1269 {
1270 	pte_t *pte;
1271 	spinlock_t *ptl;
1272 
1273 	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1274 	if (!pte)
1275 		return -ENOMEM;
1276 	arch_enter_lazy_mmu_mode();
1277 	do {
1278 		BUG_ON(!pte_none(*pte));
1279 		set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1280 		pfn++;
1281 	} while (pte++, addr += PAGE_SIZE, addr != end);
1282 	arch_leave_lazy_mmu_mode();
1283 	pte_unmap_unlock(pte - 1, ptl);
1284 	return 0;
1285 }
1286 
1287 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1288 			unsigned long addr, unsigned long end,
1289 			unsigned long pfn, pgprot_t prot)
1290 {
1291 	pmd_t *pmd;
1292 	unsigned long next;
1293 
1294 	pfn -= addr >> PAGE_SHIFT;
1295 	pmd = pmd_alloc(mm, pud, addr);
1296 	if (!pmd)
1297 		return -ENOMEM;
1298 	do {
1299 		next = pmd_addr_end(addr, end);
1300 		if (remap_pte_range(mm, pmd, addr, next,
1301 				pfn + (addr >> PAGE_SHIFT), prot))
1302 			return -ENOMEM;
1303 	} while (pmd++, addr = next, addr != end);
1304 	return 0;
1305 }
1306 
1307 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1308 			unsigned long addr, unsigned long end,
1309 			unsigned long pfn, pgprot_t prot)
1310 {
1311 	pud_t *pud;
1312 	unsigned long next;
1313 
1314 	pfn -= addr >> PAGE_SHIFT;
1315 	pud = pud_alloc(mm, pgd, addr);
1316 	if (!pud)
1317 		return -ENOMEM;
1318 	do {
1319 		next = pud_addr_end(addr, end);
1320 		if (remap_pmd_range(mm, pud, addr, next,
1321 				pfn + (addr >> PAGE_SHIFT), prot))
1322 			return -ENOMEM;
1323 	} while (pud++, addr = next, addr != end);
1324 	return 0;
1325 }
1326 
1327 /**
1328  * remap_pfn_range - remap kernel memory to userspace
1329  * @vma: user vma to map to
1330  * @addr: target user address to start at
1331  * @pfn: physical address of kernel memory
1332  * @size: size of map area
1333  * @prot: page protection flags for this mapping
1334  *
1335  *  Note: this is only safe if the mm semaphore is held when called.
1336  */
1337 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1338 		    unsigned long pfn, unsigned long size, pgprot_t prot)
1339 {
1340 	pgd_t *pgd;
1341 	unsigned long next;
1342 	unsigned long end = addr + PAGE_ALIGN(size);
1343 	struct mm_struct *mm = vma->vm_mm;
1344 	int err;
1345 
1346 	/*
1347 	 * Physically remapped pages are special. Tell the
1348 	 * rest of the world about it:
1349 	 *   VM_IO tells people not to look at these pages
1350 	 *	(accesses can have side effects).
1351 	 *   VM_RESERVED is specified all over the place, because
1352 	 *	in 2.4 it kept swapout's vma scan off this vma; but
1353 	 *	in 2.6 the LRU scan won't even find its pages, so this
1354 	 *	flag means no more than count its pages in reserved_vm,
1355 	 * 	and omit it from core dump, even when VM_IO turned off.
1356 	 *   VM_PFNMAP tells the core MM that the base pages are just
1357 	 *	raw PFN mappings, and do not have a "struct page" associated
1358 	 *	with them.
1359 	 *
1360 	 * There's a horrible special case to handle copy-on-write
1361 	 * behaviour that some programs depend on. We mark the "original"
1362 	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1363 	 */
1364 	if (is_cow_mapping(vma->vm_flags)) {
1365 		if (addr != vma->vm_start || end != vma->vm_end)
1366 			return -EINVAL;
1367 		vma->vm_pgoff = pfn;
1368 	}
1369 
1370 	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1371 
1372 	BUG_ON(addr >= end);
1373 	pfn -= addr >> PAGE_SHIFT;
1374 	pgd = pgd_offset(mm, addr);
1375 	flush_cache_range(vma, addr, end);
1376 	do {
1377 		next = pgd_addr_end(addr, end);
1378 		err = remap_pud_range(mm, pgd, addr, next,
1379 				pfn + (addr >> PAGE_SHIFT), prot);
1380 		if (err)
1381 			break;
1382 	} while (pgd++, addr = next, addr != end);
1383 	return err;
1384 }
1385 EXPORT_SYMBOL(remap_pfn_range);
1386 
1387 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1388 				     unsigned long addr, unsigned long end,
1389 				     pte_fn_t fn, void *data)
1390 {
1391 	pte_t *pte;
1392 	int err;
1393 	pgtable_t token;
1394 	spinlock_t *uninitialized_var(ptl);
1395 
1396 	pte = (mm == &init_mm) ?
1397 		pte_alloc_kernel(pmd, addr) :
1398 		pte_alloc_map_lock(mm, pmd, addr, &ptl);
1399 	if (!pte)
1400 		return -ENOMEM;
1401 
1402 	BUG_ON(pmd_huge(*pmd));
1403 
1404 	token = pmd_pgtable(*pmd);
1405 
1406 	do {
1407 		err = fn(pte, token, addr, data);
1408 		if (err)
1409 			break;
1410 	} while (pte++, addr += PAGE_SIZE, addr != end);
1411 
1412 	if (mm != &init_mm)
1413 		pte_unmap_unlock(pte-1, ptl);
1414 	return err;
1415 }
1416 
1417 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1418 				     unsigned long addr, unsigned long end,
1419 				     pte_fn_t fn, void *data)
1420 {
1421 	pmd_t *pmd;
1422 	unsigned long next;
1423 	int err;
1424 
1425 	pmd = pmd_alloc(mm, pud, addr);
1426 	if (!pmd)
1427 		return -ENOMEM;
1428 	do {
1429 		next = pmd_addr_end(addr, end);
1430 		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1431 		if (err)
1432 			break;
1433 	} while (pmd++, addr = next, addr != end);
1434 	return err;
1435 }
1436 
1437 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1438 				     unsigned long addr, unsigned long end,
1439 				     pte_fn_t fn, void *data)
1440 {
1441 	pud_t *pud;
1442 	unsigned long next;
1443 	int err;
1444 
1445 	pud = pud_alloc(mm, pgd, addr);
1446 	if (!pud)
1447 		return -ENOMEM;
1448 	do {
1449 		next = pud_addr_end(addr, end);
1450 		err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1451 		if (err)
1452 			break;
1453 	} while (pud++, addr = next, addr != end);
1454 	return err;
1455 }
1456 
1457 /*
1458  * Scan a region of virtual memory, filling in page tables as necessary
1459  * and calling a provided function on each leaf page table.
1460  */
1461 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1462 			unsigned long size, pte_fn_t fn, void *data)
1463 {
1464 	pgd_t *pgd;
1465 	unsigned long next;
1466 	unsigned long end = addr + size;
1467 	int err;
1468 
1469 	BUG_ON(addr >= end);
1470 	pgd = pgd_offset(mm, addr);
1471 	do {
1472 		next = pgd_addr_end(addr, end);
1473 		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1474 		if (err)
1475 			break;
1476 	} while (pgd++, addr = next, addr != end);
1477 	return err;
1478 }
1479 EXPORT_SYMBOL_GPL(apply_to_page_range);
1480 
1481 /*
1482  * handle_pte_fault chooses page fault handler according to an entry
1483  * which was read non-atomically.  Before making any commitment, on
1484  * those architectures or configurations (e.g. i386 with PAE) which
1485  * might give a mix of unmatched parts, do_swap_page and do_file_page
1486  * must check under lock before unmapping the pte and proceeding
1487  * (but do_wp_page is only called after already making such a check;
1488  * and do_anonymous_page and do_no_page can safely check later on).
1489  */
1490 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1491 				pte_t *page_table, pte_t orig_pte)
1492 {
1493 	int same = 1;
1494 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1495 	if (sizeof(pte_t) > sizeof(unsigned long)) {
1496 		spinlock_t *ptl = pte_lockptr(mm, pmd);
1497 		spin_lock(ptl);
1498 		same = pte_same(*page_table, orig_pte);
1499 		spin_unlock(ptl);
1500 	}
1501 #endif
1502 	pte_unmap(page_table);
1503 	return same;
1504 }
1505 
1506 /*
1507  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
1508  * servicing faults for write access.  In the normal case, do always want
1509  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
1510  * that do not have writing enabled, when used by access_process_vm.
1511  */
1512 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1513 {
1514 	if (likely(vma->vm_flags & VM_WRITE))
1515 		pte = pte_mkwrite(pte);
1516 	return pte;
1517 }
1518 
1519 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1520 {
1521 	/*
1522 	 * If the source page was a PFN mapping, we don't have
1523 	 * a "struct page" for it. We do a best-effort copy by
1524 	 * just copying from the original user address. If that
1525 	 * fails, we just zero-fill it. Live with it.
1526 	 */
1527 	if (unlikely(!src)) {
1528 		void *kaddr = kmap_atomic(dst, KM_USER0);
1529 		void __user *uaddr = (void __user *)(va & PAGE_MASK);
1530 
1531 		/*
1532 		 * This really shouldn't fail, because the page is there
1533 		 * in the page tables. But it might just be unreadable,
1534 		 * in which case we just give up and fill the result with
1535 		 * zeroes.
1536 		 */
1537 		if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1538 			memset(kaddr, 0, PAGE_SIZE);
1539 		kunmap_atomic(kaddr, KM_USER0);
1540 		flush_dcache_page(dst);
1541 	} else
1542 		copy_user_highpage(dst, src, va, vma);
1543 }
1544 
1545 /*
1546  * This routine handles present pages, when users try to write
1547  * to a shared page. It is done by copying the page to a new address
1548  * and decrementing the shared-page counter for the old page.
1549  *
1550  * Note that this routine assumes that the protection checks have been
1551  * done by the caller (the low-level page fault routine in most cases).
1552  * Thus we can safely just mark it writable once we've done any necessary
1553  * COW.
1554  *
1555  * We also mark the page dirty at this point even though the page will
1556  * change only once the write actually happens. This avoids a few races,
1557  * and potentially makes it more efficient.
1558  *
1559  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1560  * but allow concurrent faults), with pte both mapped and locked.
1561  * We return with mmap_sem still held, but pte unmapped and unlocked.
1562  */
1563 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1564 		unsigned long address, pte_t *page_table, pmd_t *pmd,
1565 		spinlock_t *ptl, pte_t orig_pte)
1566 {
1567 	struct page *old_page, *new_page;
1568 	pte_t entry;
1569 	int reuse = 0, ret = 0;
1570 	int page_mkwrite = 0;
1571 	struct page *dirty_page = NULL;
1572 
1573 	old_page = vm_normal_page(vma, address, orig_pte);
1574 	if (!old_page)
1575 		goto gotten;
1576 
1577 	/*
1578 	 * Take out anonymous pages first, anonymous shared vmas are
1579 	 * not dirty accountable.
1580 	 */
1581 	if (PageAnon(old_page)) {
1582 		if (!TestSetPageLocked(old_page)) {
1583 			reuse = can_share_swap_page(old_page);
1584 			unlock_page(old_page);
1585 		}
1586 	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1587 					(VM_WRITE|VM_SHARED))) {
1588 		/*
1589 		 * Only catch write-faults on shared writable pages,
1590 		 * read-only shared pages can get COWed by
1591 		 * get_user_pages(.write=1, .force=1).
1592 		 */
1593 		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
1594 			/*
1595 			 * Notify the address space that the page is about to
1596 			 * become writable so that it can prohibit this or wait
1597 			 * for the page to get into an appropriate state.
1598 			 *
1599 			 * We do this without the lock held, so that it can
1600 			 * sleep if it needs to.
1601 			 */
1602 			page_cache_get(old_page);
1603 			pte_unmap_unlock(page_table, ptl);
1604 
1605 			if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
1606 				goto unwritable_page;
1607 
1608 			/*
1609 			 * Since we dropped the lock we need to revalidate
1610 			 * the PTE as someone else may have changed it.  If
1611 			 * they did, we just return, as we can count on the
1612 			 * MMU to tell us if they didn't also make it writable.
1613 			 */
1614 			page_table = pte_offset_map_lock(mm, pmd, address,
1615 							 &ptl);
1616 			page_cache_release(old_page);
1617 			if (!pte_same(*page_table, orig_pte))
1618 				goto unlock;
1619 
1620 			page_mkwrite = 1;
1621 		}
1622 		dirty_page = old_page;
1623 		get_page(dirty_page);
1624 		reuse = 1;
1625 	}
1626 
1627 	if (reuse) {
1628 		flush_cache_page(vma, address, pte_pfn(orig_pte));
1629 		entry = pte_mkyoung(orig_pte);
1630 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1631 		if (ptep_set_access_flags(vma, address, page_table, entry,1))
1632 			update_mmu_cache(vma, address, entry);
1633 		ret |= VM_FAULT_WRITE;
1634 		goto unlock;
1635 	}
1636 
1637 	/*
1638 	 * Ok, we need to copy. Oh, well..
1639 	 */
1640 	page_cache_get(old_page);
1641 gotten:
1642 	pte_unmap_unlock(page_table, ptl);
1643 
1644 	if (unlikely(anon_vma_prepare(vma)))
1645 		goto oom;
1646 	VM_BUG_ON(old_page == ZERO_PAGE(0));
1647 	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
1648 	if (!new_page)
1649 		goto oom;
1650 	cow_user_page(new_page, old_page, address, vma);
1651 	__SetPageUptodate(new_page);
1652 
1653 	if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
1654 		goto oom_free_new;
1655 
1656 	/*
1657 	 * Re-check the pte - we dropped the lock
1658 	 */
1659 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1660 	if (likely(pte_same(*page_table, orig_pte))) {
1661 		if (old_page) {
1662 			page_remove_rmap(old_page, vma);
1663 			if (!PageAnon(old_page)) {
1664 				dec_mm_counter(mm, file_rss);
1665 				inc_mm_counter(mm, anon_rss);
1666 			}
1667 		} else
1668 			inc_mm_counter(mm, anon_rss);
1669 		flush_cache_page(vma, address, pte_pfn(orig_pte));
1670 		entry = mk_pte(new_page, vma->vm_page_prot);
1671 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1672 		/*
1673 		 * Clear the pte entry and flush it first, before updating the
1674 		 * pte with the new entry. This will avoid a race condition
1675 		 * seen in the presence of one thread doing SMC and another
1676 		 * thread doing COW.
1677 		 */
1678 		ptep_clear_flush(vma, address, page_table);
1679 		set_pte_at(mm, address, page_table, entry);
1680 		update_mmu_cache(vma, address, entry);
1681 		lru_cache_add_active(new_page);
1682 		page_add_new_anon_rmap(new_page, vma, address);
1683 
1684 		/* Free the old page.. */
1685 		new_page = old_page;
1686 		ret |= VM_FAULT_WRITE;
1687 	} else
1688 		mem_cgroup_uncharge_page(new_page);
1689 
1690 	if (new_page)
1691 		page_cache_release(new_page);
1692 	if (old_page)
1693 		page_cache_release(old_page);
1694 unlock:
1695 	pte_unmap_unlock(page_table, ptl);
1696 	if (dirty_page) {
1697 		if (vma->vm_file)
1698 			file_update_time(vma->vm_file);
1699 
1700 		/*
1701 		 * Yes, Virginia, this is actually required to prevent a race
1702 		 * with clear_page_dirty_for_io() from clearing the page dirty
1703 		 * bit after it clear all dirty ptes, but before a racing
1704 		 * do_wp_page installs a dirty pte.
1705 		 *
1706 		 * do_no_page is protected similarly.
1707 		 */
1708 		wait_on_page_locked(dirty_page);
1709 		set_page_dirty_balance(dirty_page, page_mkwrite);
1710 		put_page(dirty_page);
1711 	}
1712 	return ret;
1713 oom_free_new:
1714 	page_cache_release(new_page);
1715 oom:
1716 	if (old_page)
1717 		page_cache_release(old_page);
1718 	return VM_FAULT_OOM;
1719 
1720 unwritable_page:
1721 	page_cache_release(old_page);
1722 	return VM_FAULT_SIGBUS;
1723 }
1724 
1725 /*
1726  * Helper functions for unmap_mapping_range().
1727  *
1728  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1729  *
1730  * We have to restart searching the prio_tree whenever we drop the lock,
1731  * since the iterator is only valid while the lock is held, and anyway
1732  * a later vma might be split and reinserted earlier while lock dropped.
1733  *
1734  * The list of nonlinear vmas could be handled more efficiently, using
1735  * a placeholder, but handle it in the same way until a need is shown.
1736  * It is important to search the prio_tree before nonlinear list: a vma
1737  * may become nonlinear and be shifted from prio_tree to nonlinear list
1738  * while the lock is dropped; but never shifted from list to prio_tree.
1739  *
1740  * In order to make forward progress despite restarting the search,
1741  * vm_truncate_count is used to mark a vma as now dealt with, so we can
1742  * quickly skip it next time around.  Since the prio_tree search only
1743  * shows us those vmas affected by unmapping the range in question, we
1744  * can't efficiently keep all vmas in step with mapping->truncate_count:
1745  * so instead reset them all whenever it wraps back to 0 (then go to 1).
1746  * mapping->truncate_count and vma->vm_truncate_count are protected by
1747  * i_mmap_lock.
1748  *
1749  * In order to make forward progress despite repeatedly restarting some
1750  * large vma, note the restart_addr from unmap_vmas when it breaks out:
1751  * and restart from that address when we reach that vma again.  It might
1752  * have been split or merged, shrunk or extended, but never shifted: so
1753  * restart_addr remains valid so long as it remains in the vma's range.
1754  * unmap_mapping_range forces truncate_count to leap over page-aligned
1755  * values so we can save vma's restart_addr in its truncate_count field.
1756  */
1757 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1758 
1759 static void reset_vma_truncate_counts(struct address_space *mapping)
1760 {
1761 	struct vm_area_struct *vma;
1762 	struct prio_tree_iter iter;
1763 
1764 	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1765 		vma->vm_truncate_count = 0;
1766 	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1767 		vma->vm_truncate_count = 0;
1768 }
1769 
1770 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1771 		unsigned long start_addr, unsigned long end_addr,
1772 		struct zap_details *details)
1773 {
1774 	unsigned long restart_addr;
1775 	int need_break;
1776 
1777 	/*
1778 	 * files that support invalidating or truncating portions of the
1779 	 * file from under mmaped areas must have their ->fault function
1780 	 * return a locked page (and set VM_FAULT_LOCKED in the return).
1781 	 * This provides synchronisation against concurrent unmapping here.
1782 	 */
1783 
1784 again:
1785 	restart_addr = vma->vm_truncate_count;
1786 	if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1787 		start_addr = restart_addr;
1788 		if (start_addr >= end_addr) {
1789 			/* Top of vma has been split off since last time */
1790 			vma->vm_truncate_count = details->truncate_count;
1791 			return 0;
1792 		}
1793 	}
1794 
1795 	restart_addr = zap_page_range(vma, start_addr,
1796 					end_addr - start_addr, details);
1797 	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
1798 
1799 	if (restart_addr >= end_addr) {
1800 		/* We have now completed this vma: mark it so */
1801 		vma->vm_truncate_count = details->truncate_count;
1802 		if (!need_break)
1803 			return 0;
1804 	} else {
1805 		/* Note restart_addr in vma's truncate_count field */
1806 		vma->vm_truncate_count = restart_addr;
1807 		if (!need_break)
1808 			goto again;
1809 	}
1810 
1811 	spin_unlock(details->i_mmap_lock);
1812 	cond_resched();
1813 	spin_lock(details->i_mmap_lock);
1814 	return -EINTR;
1815 }
1816 
1817 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1818 					    struct zap_details *details)
1819 {
1820 	struct vm_area_struct *vma;
1821 	struct prio_tree_iter iter;
1822 	pgoff_t vba, vea, zba, zea;
1823 
1824 restart:
1825 	vma_prio_tree_foreach(vma, &iter, root,
1826 			details->first_index, details->last_index) {
1827 		/* Skip quickly over those we have already dealt with */
1828 		if (vma->vm_truncate_count == details->truncate_count)
1829 			continue;
1830 
1831 		vba = vma->vm_pgoff;
1832 		vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1833 		/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1834 		zba = details->first_index;
1835 		if (zba < vba)
1836 			zba = vba;
1837 		zea = details->last_index;
1838 		if (zea > vea)
1839 			zea = vea;
1840 
1841 		if (unmap_mapping_range_vma(vma,
1842 			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1843 			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1844 				details) < 0)
1845 			goto restart;
1846 	}
1847 }
1848 
1849 static inline void unmap_mapping_range_list(struct list_head *head,
1850 					    struct zap_details *details)
1851 {
1852 	struct vm_area_struct *vma;
1853 
1854 	/*
1855 	 * In nonlinear VMAs there is no correspondence between virtual address
1856 	 * offset and file offset.  So we must perform an exhaustive search
1857 	 * across *all* the pages in each nonlinear VMA, not just the pages
1858 	 * whose virtual address lies outside the file truncation point.
1859 	 */
1860 restart:
1861 	list_for_each_entry(vma, head, shared.vm_set.list) {
1862 		/* Skip quickly over those we have already dealt with */
1863 		if (vma->vm_truncate_count == details->truncate_count)
1864 			continue;
1865 		details->nonlinear_vma = vma;
1866 		if (unmap_mapping_range_vma(vma, vma->vm_start,
1867 					vma->vm_end, details) < 0)
1868 			goto restart;
1869 	}
1870 }
1871 
1872 /**
1873  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
1874  * @mapping: the address space containing mmaps to be unmapped.
1875  * @holebegin: byte in first page to unmap, relative to the start of
1876  * the underlying file.  This will be rounded down to a PAGE_SIZE
1877  * boundary.  Note that this is different from vmtruncate(), which
1878  * must keep the partial page.  In contrast, we must get rid of
1879  * partial pages.
1880  * @holelen: size of prospective hole in bytes.  This will be rounded
1881  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
1882  * end of the file.
1883  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1884  * but 0 when invalidating pagecache, don't throw away private data.
1885  */
1886 void unmap_mapping_range(struct address_space *mapping,
1887 		loff_t const holebegin, loff_t const holelen, int even_cows)
1888 {
1889 	struct zap_details details;
1890 	pgoff_t hba = holebegin >> PAGE_SHIFT;
1891 	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1892 
1893 	/* Check for overflow. */
1894 	if (sizeof(holelen) > sizeof(hlen)) {
1895 		long long holeend =
1896 			(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1897 		if (holeend & ~(long long)ULONG_MAX)
1898 			hlen = ULONG_MAX - hba + 1;
1899 	}
1900 
1901 	details.check_mapping = even_cows? NULL: mapping;
1902 	details.nonlinear_vma = NULL;
1903 	details.first_index = hba;
1904 	details.last_index = hba + hlen - 1;
1905 	if (details.last_index < details.first_index)
1906 		details.last_index = ULONG_MAX;
1907 	details.i_mmap_lock = &mapping->i_mmap_lock;
1908 
1909 	spin_lock(&mapping->i_mmap_lock);
1910 
1911 	/* Protect against endless unmapping loops */
1912 	mapping->truncate_count++;
1913 	if (unlikely(is_restart_addr(mapping->truncate_count))) {
1914 		if (mapping->truncate_count == 0)
1915 			reset_vma_truncate_counts(mapping);
1916 		mapping->truncate_count++;
1917 	}
1918 	details.truncate_count = mapping->truncate_count;
1919 
1920 	if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1921 		unmap_mapping_range_tree(&mapping->i_mmap, &details);
1922 	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1923 		unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1924 	spin_unlock(&mapping->i_mmap_lock);
1925 }
1926 EXPORT_SYMBOL(unmap_mapping_range);
1927 
1928 /**
1929  * vmtruncate - unmap mappings "freed" by truncate() syscall
1930  * @inode: inode of the file used
1931  * @offset: file offset to start truncating
1932  *
1933  * NOTE! We have to be ready to update the memory sharing
1934  * between the file and the memory map for a potential last
1935  * incomplete page.  Ugly, but necessary.
1936  */
1937 int vmtruncate(struct inode * inode, loff_t offset)
1938 {
1939 	if (inode->i_size < offset) {
1940 		unsigned long limit;
1941 
1942 		limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1943 		if (limit != RLIM_INFINITY && offset > limit)
1944 			goto out_sig;
1945 		if (offset > inode->i_sb->s_maxbytes)
1946 			goto out_big;
1947 		i_size_write(inode, offset);
1948 	} else {
1949 		struct address_space *mapping = inode->i_mapping;
1950 
1951 		/*
1952 		 * truncation of in-use swapfiles is disallowed - it would
1953 		 * cause subsequent swapout to scribble on the now-freed
1954 		 * blocks.
1955 		 */
1956 		if (IS_SWAPFILE(inode))
1957 			return -ETXTBSY;
1958 		i_size_write(inode, offset);
1959 
1960 		/*
1961 		 * unmap_mapping_range is called twice, first simply for
1962 		 * efficiency so that truncate_inode_pages does fewer
1963 		 * single-page unmaps.  However after this first call, and
1964 		 * before truncate_inode_pages finishes, it is possible for
1965 		 * private pages to be COWed, which remain after
1966 		 * truncate_inode_pages finishes, hence the second
1967 		 * unmap_mapping_range call must be made for correctness.
1968 		 */
1969 		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1970 		truncate_inode_pages(mapping, offset);
1971 		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1972 	}
1973 
1974 	if (inode->i_op && inode->i_op->truncate)
1975 		inode->i_op->truncate(inode);
1976 	return 0;
1977 
1978 out_sig:
1979 	send_sig(SIGXFSZ, current, 0);
1980 out_big:
1981 	return -EFBIG;
1982 }
1983 EXPORT_SYMBOL(vmtruncate);
1984 
1985 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
1986 {
1987 	struct address_space *mapping = inode->i_mapping;
1988 
1989 	/*
1990 	 * If the underlying filesystem is not going to provide
1991 	 * a way to truncate a range of blocks (punch a hole) -
1992 	 * we should return failure right now.
1993 	 */
1994 	if (!inode->i_op || !inode->i_op->truncate_range)
1995 		return -ENOSYS;
1996 
1997 	mutex_lock(&inode->i_mutex);
1998 	down_write(&inode->i_alloc_sem);
1999 	unmap_mapping_range(mapping, offset, (end - offset), 1);
2000 	truncate_inode_pages_range(mapping, offset, end);
2001 	unmap_mapping_range(mapping, offset, (end - offset), 1);
2002 	inode->i_op->truncate_range(inode, offset, end);
2003 	up_write(&inode->i_alloc_sem);
2004 	mutex_unlock(&inode->i_mutex);
2005 
2006 	return 0;
2007 }
2008 
2009 /*
2010  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2011  * but allow concurrent faults), and pte mapped but not yet locked.
2012  * We return with mmap_sem still held, but pte unmapped and unlocked.
2013  */
2014 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2015 		unsigned long address, pte_t *page_table, pmd_t *pmd,
2016 		int write_access, pte_t orig_pte)
2017 {
2018 	spinlock_t *ptl;
2019 	struct page *page;
2020 	swp_entry_t entry;
2021 	pte_t pte;
2022 	int ret = 0;
2023 
2024 	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2025 		goto out;
2026 
2027 	entry = pte_to_swp_entry(orig_pte);
2028 	if (is_migration_entry(entry)) {
2029 		migration_entry_wait(mm, pmd, address);
2030 		goto out;
2031 	}
2032 	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2033 	page = lookup_swap_cache(entry);
2034 	if (!page) {
2035 		grab_swap_token(); /* Contend for token _before_ read-in */
2036 		page = swapin_readahead(entry,
2037 					GFP_HIGHUSER_MOVABLE, vma, address);
2038 		if (!page) {
2039 			/*
2040 			 * Back out if somebody else faulted in this pte
2041 			 * while we released the pte lock.
2042 			 */
2043 			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2044 			if (likely(pte_same(*page_table, orig_pte)))
2045 				ret = VM_FAULT_OOM;
2046 			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2047 			goto unlock;
2048 		}
2049 
2050 		/* Had to read the page from swap area: Major fault */
2051 		ret = VM_FAULT_MAJOR;
2052 		count_vm_event(PGMAJFAULT);
2053 	}
2054 
2055 	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2056 		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2057 		ret = VM_FAULT_OOM;
2058 		goto out;
2059 	}
2060 
2061 	mark_page_accessed(page);
2062 	lock_page(page);
2063 	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2064 
2065 	/*
2066 	 * Back out if somebody else already faulted in this pte.
2067 	 */
2068 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2069 	if (unlikely(!pte_same(*page_table, orig_pte)))
2070 		goto out_nomap;
2071 
2072 	if (unlikely(!PageUptodate(page))) {
2073 		ret = VM_FAULT_SIGBUS;
2074 		goto out_nomap;
2075 	}
2076 
2077 	/* The page isn't present yet, go ahead with the fault. */
2078 
2079 	inc_mm_counter(mm, anon_rss);
2080 	pte = mk_pte(page, vma->vm_page_prot);
2081 	if (write_access && can_share_swap_page(page)) {
2082 		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2083 		write_access = 0;
2084 	}
2085 
2086 	flush_icache_page(vma, page);
2087 	set_pte_at(mm, address, page_table, pte);
2088 	page_add_anon_rmap(page, vma, address);
2089 
2090 	swap_free(entry);
2091 	if (vm_swap_full())
2092 		remove_exclusive_swap_page(page);
2093 	unlock_page(page);
2094 
2095 	if (write_access) {
2096 		ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2097 		if (ret & VM_FAULT_ERROR)
2098 			ret &= VM_FAULT_ERROR;
2099 		goto out;
2100 	}
2101 
2102 	/* No need to invalidate - it was non-present before */
2103 	update_mmu_cache(vma, address, pte);
2104 unlock:
2105 	pte_unmap_unlock(page_table, ptl);
2106 out:
2107 	return ret;
2108 out_nomap:
2109 	mem_cgroup_uncharge_page(page);
2110 	pte_unmap_unlock(page_table, ptl);
2111 	unlock_page(page);
2112 	page_cache_release(page);
2113 	return ret;
2114 }
2115 
2116 /*
2117  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2118  * but allow concurrent faults), and pte mapped but not yet locked.
2119  * We return with mmap_sem still held, but pte unmapped and unlocked.
2120  */
2121 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2122 		unsigned long address, pte_t *page_table, pmd_t *pmd,
2123 		int write_access)
2124 {
2125 	struct page *page;
2126 	spinlock_t *ptl;
2127 	pte_t entry;
2128 
2129 	/* Allocate our own private page. */
2130 	pte_unmap(page_table);
2131 
2132 	if (unlikely(anon_vma_prepare(vma)))
2133 		goto oom;
2134 	page = alloc_zeroed_user_highpage_movable(vma, address);
2135 	if (!page)
2136 		goto oom;
2137 	__SetPageUptodate(page);
2138 
2139 	if (mem_cgroup_charge(page, mm, GFP_KERNEL))
2140 		goto oom_free_page;
2141 
2142 	entry = mk_pte(page, vma->vm_page_prot);
2143 	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2144 
2145 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2146 	if (!pte_none(*page_table))
2147 		goto release;
2148 	inc_mm_counter(mm, anon_rss);
2149 	lru_cache_add_active(page);
2150 	page_add_new_anon_rmap(page, vma, address);
2151 	set_pte_at(mm, address, page_table, entry);
2152 
2153 	/* No need to invalidate - it was non-present before */
2154 	update_mmu_cache(vma, address, entry);
2155 unlock:
2156 	pte_unmap_unlock(page_table, ptl);
2157 	return 0;
2158 release:
2159 	mem_cgroup_uncharge_page(page);
2160 	page_cache_release(page);
2161 	goto unlock;
2162 oom_free_page:
2163 	page_cache_release(page);
2164 oom:
2165 	return VM_FAULT_OOM;
2166 }
2167 
2168 /*
2169  * __do_fault() tries to create a new page mapping. It aggressively
2170  * tries to share with existing pages, but makes a separate copy if
2171  * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
2172  * the next page fault.
2173  *
2174  * As this is called only for pages that do not currently exist, we
2175  * do not need to flush old virtual caches or the TLB.
2176  *
2177  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2178  * but allow concurrent faults), and pte neither mapped nor locked.
2179  * We return with mmap_sem still held, but pte unmapped and unlocked.
2180  */
2181 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2182 		unsigned long address, pmd_t *pmd,
2183 		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2184 {
2185 	pte_t *page_table;
2186 	spinlock_t *ptl;
2187 	struct page *page;
2188 	pte_t entry;
2189 	int anon = 0;
2190 	struct page *dirty_page = NULL;
2191 	struct vm_fault vmf;
2192 	int ret;
2193 	int page_mkwrite = 0;
2194 
2195 	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2196 	vmf.pgoff = pgoff;
2197 	vmf.flags = flags;
2198 	vmf.page = NULL;
2199 
2200 	BUG_ON(vma->vm_flags & VM_PFNMAP);
2201 
2202 	if (likely(vma->vm_ops->fault)) {
2203 		ret = vma->vm_ops->fault(vma, &vmf);
2204 		if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2205 			return ret;
2206 	} else {
2207 		/* Legacy ->nopage path */
2208 		ret = 0;
2209 		vmf.page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
2210 		/* no page was available -- either SIGBUS or OOM */
2211 		if (unlikely(vmf.page == NOPAGE_SIGBUS))
2212 			return VM_FAULT_SIGBUS;
2213 		else if (unlikely(vmf.page == NOPAGE_OOM))
2214 			return VM_FAULT_OOM;
2215 	}
2216 
2217 	/*
2218 	 * For consistency in subsequent calls, make the faulted page always
2219 	 * locked.
2220 	 */
2221 	if (unlikely(!(ret & VM_FAULT_LOCKED)))
2222 		lock_page(vmf.page);
2223 	else
2224 		VM_BUG_ON(!PageLocked(vmf.page));
2225 
2226 	/*
2227 	 * Should we do an early C-O-W break?
2228 	 */
2229 	page = vmf.page;
2230 	if (flags & FAULT_FLAG_WRITE) {
2231 		if (!(vma->vm_flags & VM_SHARED)) {
2232 			anon = 1;
2233 			if (unlikely(anon_vma_prepare(vma))) {
2234 				ret = VM_FAULT_OOM;
2235 				goto out;
2236 			}
2237 			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
2238 						vma, address);
2239 			if (!page) {
2240 				ret = VM_FAULT_OOM;
2241 				goto out;
2242 			}
2243 			copy_user_highpage(page, vmf.page, address, vma);
2244 			__SetPageUptodate(page);
2245 		} else {
2246 			/*
2247 			 * If the page will be shareable, see if the backing
2248 			 * address space wants to know that the page is about
2249 			 * to become writable
2250 			 */
2251 			if (vma->vm_ops->page_mkwrite) {
2252 				unlock_page(page);
2253 				if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
2254 					ret = VM_FAULT_SIGBUS;
2255 					anon = 1; /* no anon but release vmf.page */
2256 					goto out_unlocked;
2257 				}
2258 				lock_page(page);
2259 				/*
2260 				 * XXX: this is not quite right (racy vs
2261 				 * invalidate) to unlock and relock the page
2262 				 * like this, however a better fix requires
2263 				 * reworking page_mkwrite locking API, which
2264 				 * is better done later.
2265 				 */
2266 				if (!page->mapping) {
2267 					ret = 0;
2268 					anon = 1; /* no anon but release vmf.page */
2269 					goto out;
2270 				}
2271 				page_mkwrite = 1;
2272 			}
2273 		}
2274 
2275 	}
2276 
2277 	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2278 		ret = VM_FAULT_OOM;
2279 		goto out;
2280 	}
2281 
2282 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2283 
2284 	/*
2285 	 * This silly early PAGE_DIRTY setting removes a race
2286 	 * due to the bad i386 page protection. But it's valid
2287 	 * for other architectures too.
2288 	 *
2289 	 * Note that if write_access is true, we either now have
2290 	 * an exclusive copy of the page, or this is a shared mapping,
2291 	 * so we can make it writable and dirty to avoid having to
2292 	 * handle that later.
2293 	 */
2294 	/* Only go through if we didn't race with anybody else... */
2295 	if (likely(pte_same(*page_table, orig_pte))) {
2296 		flush_icache_page(vma, page);
2297 		entry = mk_pte(page, vma->vm_page_prot);
2298 		if (flags & FAULT_FLAG_WRITE)
2299 			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2300 		set_pte_at(mm, address, page_table, entry);
2301 		if (anon) {
2302                         inc_mm_counter(mm, anon_rss);
2303                         lru_cache_add_active(page);
2304                         page_add_new_anon_rmap(page, vma, address);
2305 		} else {
2306 			inc_mm_counter(mm, file_rss);
2307 			page_add_file_rmap(page);
2308 			if (flags & FAULT_FLAG_WRITE) {
2309 				dirty_page = page;
2310 				get_page(dirty_page);
2311 			}
2312 		}
2313 
2314 		/* no need to invalidate: a not-present page won't be cached */
2315 		update_mmu_cache(vma, address, entry);
2316 	} else {
2317 		mem_cgroup_uncharge_page(page);
2318 		if (anon)
2319 			page_cache_release(page);
2320 		else
2321 			anon = 1; /* no anon but release faulted_page */
2322 	}
2323 
2324 	pte_unmap_unlock(page_table, ptl);
2325 
2326 out:
2327 	unlock_page(vmf.page);
2328 out_unlocked:
2329 	if (anon)
2330 		page_cache_release(vmf.page);
2331 	else if (dirty_page) {
2332 		if (vma->vm_file)
2333 			file_update_time(vma->vm_file);
2334 
2335 		set_page_dirty_balance(dirty_page, page_mkwrite);
2336 		put_page(dirty_page);
2337 	}
2338 
2339 	return ret;
2340 }
2341 
2342 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2343 		unsigned long address, pte_t *page_table, pmd_t *pmd,
2344 		int write_access, pte_t orig_pte)
2345 {
2346 	pgoff_t pgoff = (((address & PAGE_MASK)
2347 			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2348 	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);
2349 
2350 	pte_unmap(page_table);
2351 	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2352 }
2353 
2354 
2355 /*
2356  * do_no_pfn() tries to create a new page mapping for a page without
2357  * a struct_page backing it
2358  *
2359  * As this is called only for pages that do not currently exist, we
2360  * do not need to flush old virtual caches or the TLB.
2361  *
2362  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2363  * but allow concurrent faults), and pte mapped but not yet locked.
2364  * We return with mmap_sem still held, but pte unmapped and unlocked.
2365  *
2366  * It is expected that the ->nopfn handler always returns the same pfn
2367  * for a given virtual mapping.
2368  *
2369  * Mark this `noinline' to prevent it from bloating the main pagefault code.
2370  */
2371 static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma,
2372 		     unsigned long address, pte_t *page_table, pmd_t *pmd,
2373 		     int write_access)
2374 {
2375 	spinlock_t *ptl;
2376 	pte_t entry;
2377 	unsigned long pfn;
2378 
2379 	pte_unmap(page_table);
2380 	BUG_ON(!(vma->vm_flags & VM_PFNMAP));
2381 	BUG_ON(is_cow_mapping(vma->vm_flags));
2382 
2383 	pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK);
2384 	if (unlikely(pfn == NOPFN_OOM))
2385 		return VM_FAULT_OOM;
2386 	else if (unlikely(pfn == NOPFN_SIGBUS))
2387 		return VM_FAULT_SIGBUS;
2388 	else if (unlikely(pfn == NOPFN_REFAULT))
2389 		return 0;
2390 
2391 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2392 
2393 	/* Only go through if we didn't race with anybody else... */
2394 	if (pte_none(*page_table)) {
2395 		entry = pfn_pte(pfn, vma->vm_page_prot);
2396 		if (write_access)
2397 			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2398 		set_pte_at(mm, address, page_table, entry);
2399 	}
2400 	pte_unmap_unlock(page_table, ptl);
2401 	return 0;
2402 }
2403 
2404 /*
2405  * Fault of a previously existing named mapping. Repopulate the pte
2406  * from the encoded file_pte if possible. This enables swappable
2407  * nonlinear vmas.
2408  *
2409  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2410  * but allow concurrent faults), and pte mapped but not yet locked.
2411  * We return with mmap_sem still held, but pte unmapped and unlocked.
2412  */
2413 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2414 		unsigned long address, pte_t *page_table, pmd_t *pmd,
2415 		int write_access, pte_t orig_pte)
2416 {
2417 	unsigned int flags = FAULT_FLAG_NONLINEAR |
2418 				(write_access ? FAULT_FLAG_WRITE : 0);
2419 	pgoff_t pgoff;
2420 
2421 	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2422 		return 0;
2423 
2424 	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
2425 			!(vma->vm_flags & VM_CAN_NONLINEAR))) {
2426 		/*
2427 		 * Page table corrupted: show pte and kill process.
2428 		 */
2429 		print_bad_pte(vma, orig_pte, address);
2430 		return VM_FAULT_OOM;
2431 	}
2432 
2433 	pgoff = pte_to_pgoff(orig_pte);
2434 	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2435 }
2436 
2437 /*
2438  * These routines also need to handle stuff like marking pages dirty
2439  * and/or accessed for architectures that don't do it in hardware (most
2440  * RISC architectures).  The early dirtying is also good on the i386.
2441  *
2442  * There is also a hook called "update_mmu_cache()" that architectures
2443  * with external mmu caches can use to update those (ie the Sparc or
2444  * PowerPC hashed page tables that act as extended TLBs).
2445  *
2446  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2447  * but allow concurrent faults), and pte mapped but not yet locked.
2448  * We return with mmap_sem still held, but pte unmapped and unlocked.
2449  */
2450 static inline int handle_pte_fault(struct mm_struct *mm,
2451 		struct vm_area_struct *vma, unsigned long address,
2452 		pte_t *pte, pmd_t *pmd, int write_access)
2453 {
2454 	pte_t entry;
2455 	spinlock_t *ptl;
2456 
2457 	entry = *pte;
2458 	if (!pte_present(entry)) {
2459 		if (pte_none(entry)) {
2460 			if (vma->vm_ops) {
2461 				if (vma->vm_ops->fault || vma->vm_ops->nopage)
2462 					return do_linear_fault(mm, vma, address,
2463 						pte, pmd, write_access, entry);
2464 				if (unlikely(vma->vm_ops->nopfn))
2465 					return do_no_pfn(mm, vma, address, pte,
2466 							 pmd, write_access);
2467 			}
2468 			return do_anonymous_page(mm, vma, address,
2469 						 pte, pmd, write_access);
2470 		}
2471 		if (pte_file(entry))
2472 			return do_nonlinear_fault(mm, vma, address,
2473 					pte, pmd, write_access, entry);
2474 		return do_swap_page(mm, vma, address,
2475 					pte, pmd, write_access, entry);
2476 	}
2477 
2478 	ptl = pte_lockptr(mm, pmd);
2479 	spin_lock(ptl);
2480 	if (unlikely(!pte_same(*pte, entry)))
2481 		goto unlock;
2482 	if (write_access) {
2483 		if (!pte_write(entry))
2484 			return do_wp_page(mm, vma, address,
2485 					pte, pmd, ptl, entry);
2486 		entry = pte_mkdirty(entry);
2487 	}
2488 	entry = pte_mkyoung(entry);
2489 	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2490 		update_mmu_cache(vma, address, entry);
2491 	} else {
2492 		/*
2493 		 * This is needed only for protection faults but the arch code
2494 		 * is not yet telling us if this is a protection fault or not.
2495 		 * This still avoids useless tlb flushes for .text page faults
2496 		 * with threads.
2497 		 */
2498 		if (write_access)
2499 			flush_tlb_page(vma, address);
2500 	}
2501 unlock:
2502 	pte_unmap_unlock(pte, ptl);
2503 	return 0;
2504 }
2505 
2506 /*
2507  * By the time we get here, we already hold the mm semaphore
2508  */
2509 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2510 		unsigned long address, int write_access)
2511 {
2512 	pgd_t *pgd;
2513 	pud_t *pud;
2514 	pmd_t *pmd;
2515 	pte_t *pte;
2516 
2517 	__set_current_state(TASK_RUNNING);
2518 
2519 	count_vm_event(PGFAULT);
2520 
2521 	if (unlikely(is_vm_hugetlb_page(vma)))
2522 		return hugetlb_fault(mm, vma, address, write_access);
2523 
2524 	pgd = pgd_offset(mm, address);
2525 	pud = pud_alloc(mm, pgd, address);
2526 	if (!pud)
2527 		return VM_FAULT_OOM;
2528 	pmd = pmd_alloc(mm, pud, address);
2529 	if (!pmd)
2530 		return VM_FAULT_OOM;
2531 	pte = pte_alloc_map(mm, pmd, address);
2532 	if (!pte)
2533 		return VM_FAULT_OOM;
2534 
2535 	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2536 }
2537 
2538 #ifndef __PAGETABLE_PUD_FOLDED
2539 /*
2540  * Allocate page upper directory.
2541  * We've already handled the fast-path in-line.
2542  */
2543 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2544 {
2545 	pud_t *new = pud_alloc_one(mm, address);
2546 	if (!new)
2547 		return -ENOMEM;
2548 
2549 	spin_lock(&mm->page_table_lock);
2550 	if (pgd_present(*pgd))		/* Another has populated it */
2551 		pud_free(mm, new);
2552 	else
2553 		pgd_populate(mm, pgd, new);
2554 	spin_unlock(&mm->page_table_lock);
2555 	return 0;
2556 }
2557 #endif /* __PAGETABLE_PUD_FOLDED */
2558 
2559 #ifndef __PAGETABLE_PMD_FOLDED
2560 /*
2561  * Allocate page middle directory.
2562  * We've already handled the fast-path in-line.
2563  */
2564 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2565 {
2566 	pmd_t *new = pmd_alloc_one(mm, address);
2567 	if (!new)
2568 		return -ENOMEM;
2569 
2570 	spin_lock(&mm->page_table_lock);
2571 #ifndef __ARCH_HAS_4LEVEL_HACK
2572 	if (pud_present(*pud))		/* Another has populated it */
2573 		pmd_free(mm, new);
2574 	else
2575 		pud_populate(mm, pud, new);
2576 #else
2577 	if (pgd_present(*pud))		/* Another has populated it */
2578 		pmd_free(mm, new);
2579 	else
2580 		pgd_populate(mm, pud, new);
2581 #endif /* __ARCH_HAS_4LEVEL_HACK */
2582 	spin_unlock(&mm->page_table_lock);
2583 	return 0;
2584 }
2585 #endif /* __PAGETABLE_PMD_FOLDED */
2586 
2587 int make_pages_present(unsigned long addr, unsigned long end)
2588 {
2589 	int ret, len, write;
2590 	struct vm_area_struct * vma;
2591 
2592 	vma = find_vma(current->mm, addr);
2593 	if (!vma)
2594 		return -1;
2595 	write = (vma->vm_flags & VM_WRITE) != 0;
2596 	BUG_ON(addr >= end);
2597 	BUG_ON(end > vma->vm_end);
2598 	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
2599 	ret = get_user_pages(current, current->mm, addr,
2600 			len, write, 0, NULL, NULL);
2601 	if (ret < 0)
2602 		return ret;
2603 	return ret == len ? 0 : -1;
2604 }
2605 
2606 #if !defined(__HAVE_ARCH_GATE_AREA)
2607 
2608 #if defined(AT_SYSINFO_EHDR)
2609 static struct vm_area_struct gate_vma;
2610 
2611 static int __init gate_vma_init(void)
2612 {
2613 	gate_vma.vm_mm = NULL;
2614 	gate_vma.vm_start = FIXADDR_USER_START;
2615 	gate_vma.vm_end = FIXADDR_USER_END;
2616 	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
2617 	gate_vma.vm_page_prot = __P101;
2618 	/*
2619 	 * Make sure the vDSO gets into every core dump.
2620 	 * Dumping its contents makes post-mortem fully interpretable later
2621 	 * without matching up the same kernel and hardware config to see
2622 	 * what PC values meant.
2623 	 */
2624 	gate_vma.vm_flags |= VM_ALWAYSDUMP;
2625 	return 0;
2626 }
2627 __initcall(gate_vma_init);
2628 #endif
2629 
2630 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2631 {
2632 #ifdef AT_SYSINFO_EHDR
2633 	return &gate_vma;
2634 #else
2635 	return NULL;
2636 #endif
2637 }
2638 
2639 int in_gate_area_no_task(unsigned long addr)
2640 {
2641 #ifdef AT_SYSINFO_EHDR
2642 	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2643 		return 1;
2644 #endif
2645 	return 0;
2646 }
2647 
2648 #endif	/* __HAVE_ARCH_GATE_AREA */
2649 
2650 /*
2651  * Access another process' address space.
2652  * Source/target buffer must be kernel space,
2653  * Do not walk the page table directly, use get_user_pages
2654  */
2655 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2656 {
2657 	struct mm_struct *mm;
2658 	struct vm_area_struct *vma;
2659 	struct page *page;
2660 	void *old_buf = buf;
2661 
2662 	mm = get_task_mm(tsk);
2663 	if (!mm)
2664 		return 0;
2665 
2666 	down_read(&mm->mmap_sem);
2667 	/* ignore errors, just check how much was successfully transferred */
2668 	while (len) {
2669 		int bytes, ret, offset;
2670 		void *maddr;
2671 
2672 		ret = get_user_pages(tsk, mm, addr, 1,
2673 				write, 1, &page, &vma);
2674 		if (ret <= 0)
2675 			break;
2676 
2677 		bytes = len;
2678 		offset = addr & (PAGE_SIZE-1);
2679 		if (bytes > PAGE_SIZE-offset)
2680 			bytes = PAGE_SIZE-offset;
2681 
2682 		maddr = kmap(page);
2683 		if (write) {
2684 			copy_to_user_page(vma, page, addr,
2685 					  maddr + offset, buf, bytes);
2686 			set_page_dirty_lock(page);
2687 		} else {
2688 			copy_from_user_page(vma, page, addr,
2689 					    buf, maddr + offset, bytes);
2690 		}
2691 		kunmap(page);
2692 		page_cache_release(page);
2693 		len -= bytes;
2694 		buf += bytes;
2695 		addr += bytes;
2696 	}
2697 	up_read(&mm->mmap_sem);
2698 	mmput(mm);
2699 
2700 	return buf - old_buf;
2701 }
2702 
2703 /*
2704  * Print the name of a VMA.
2705  */
2706 void print_vma_addr(char *prefix, unsigned long ip)
2707 {
2708 	struct mm_struct *mm = current->mm;
2709 	struct vm_area_struct *vma;
2710 
2711 	/*
2712 	 * Do not print if we are in atomic
2713 	 * contexts (in exception stacks, etc.):
2714 	 */
2715 	if (preempt_count())
2716 		return;
2717 
2718 	down_read(&mm->mmap_sem);
2719 	vma = find_vma(mm, ip);
2720 	if (vma && vma->vm_file) {
2721 		struct file *f = vma->vm_file;
2722 		char *buf = (char *)__get_free_page(GFP_KERNEL);
2723 		if (buf) {
2724 			char *p, *s;
2725 
2726 			p = d_path(&f->f_path, buf, PAGE_SIZE);
2727 			if (IS_ERR(p))
2728 				p = "?";
2729 			s = strrchr(p, '/');
2730 			if (s)
2731 				p = s+1;
2732 			printk("%s%s[%lx+%lx]", prefix, p,
2733 					vma->vm_start,
2734 					vma->vm_end - vma->vm_start);
2735 			free_page((unsigned long)buf);
2736 		}
2737 	}
2738 	up_read(&current->mm->mmap_sem);
2739 }
2740