1 // SPDX-License-Identifier: GPL-2.0-only
5 * Replacement code for mm functions to support CPU's that don't
6 * have any form of memory management unit (thus no virtual memory).
8 * See Documentation/admin-guide/mm/nommu-mmap.rst
10 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
11 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
12 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
13 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
14 * Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 #include <linux/export.h>
21 #include <linux/sched/mm.h>
22 #include <linux/mman.h>
23 #include <linux/swap.h>
24 #include <linux/file.h>
25 #include <linux/highmem.h>
26 #include <linux/pagemap.h>
27 #include <linux/slab.h>
28 #include <linux/vmalloc.h>
29 #include <linux/backing-dev.h>
30 #include <linux/compiler.h>
31 #include <linux/mount.h>
32 #include <linux/personality.h>
33 #include <linux/security.h>
34 #include <linux/syscalls.h>
35 #include <linux/audit.h>
36 #include <linux/printk.h>
38 #include <linux/uaccess.h>
39 #include <linux/uio.h>
41 #include <asm/tlbflush.h>
42 #include <asm/mmu_context.h>
46 EXPORT_SYMBOL(high_memory
);
48 unsigned long max_mapnr
;
49 EXPORT_SYMBOL(max_mapnr
);
50 unsigned long highest_memmap_pfn
;
51 int sysctl_nr_trim_pages
= CONFIG_NOMMU_INITIAL_TRIM_EXCESS
;
52 int heap_stack_gap
= 0;
54 atomic_long_t mmap_pages_allocated
;
56 EXPORT_SYMBOL(mem_map
);
58 /* list of mapped, potentially shareable regions */
59 static struct kmem_cache
*vm_region_jar
;
60 struct rb_root nommu_region_tree
= RB_ROOT
;
61 DECLARE_RWSEM(nommu_region_sem
);
63 const struct vm_operations_struct generic_file_vm_ops
= {
67 * Return the total memory allocated for this pointer, not
68 * just what the caller asked for.
70 * Doesn't have to be accurate, i.e. may have races.
72 unsigned int kobjsize(const void *objp
)
77 * If the object we have should not have ksize performed on it,
80 if (!objp
|| !virt_addr_valid(objp
))
83 page
= virt_to_head_page(objp
);
86 * If the allocator sets PageSlab, we know the pointer came from
93 * If it's not a compound page, see if we have a matching VMA
94 * region. This test is intentionally done in reverse order,
95 * so if there's no VMA, we still fall through and hand back
96 * PAGE_SIZE for 0-order pages.
98 if (!PageCompound(page
)) {
99 struct vm_area_struct
*vma
;
101 vma
= find_vma(current
->mm
, (unsigned long)objp
);
103 return vma
->vm_end
- vma
->vm_start
;
107 * The ksize() function is only guaranteed to work for pointers
108 * returned by kmalloc(). So handle arbitrary pointers here.
110 return page_size(page
);
114 * follow_pfn - look up PFN at a user virtual address
115 * @vma: memory mapping
116 * @address: user virtual address
117 * @pfn: location to store found PFN
119 * Only IO mappings and raw PFN mappings are allowed.
121 * Returns zero and the pfn at @pfn on success, -ve otherwise.
123 int follow_pfn(struct vm_area_struct
*vma
, unsigned long address
,
126 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
129 *pfn
= address
>> PAGE_SHIFT
;
132 EXPORT_SYMBOL(follow_pfn
);
134 LIST_HEAD(vmap_area_list
);
136 void vfree(const void *addr
)
140 EXPORT_SYMBOL(vfree
);
142 void *__vmalloc(unsigned long size
, gfp_t gfp_mask
)
145 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
146 * returns only a logical address.
148 return kmalloc(size
, (gfp_mask
| __GFP_COMP
) & ~__GFP_HIGHMEM
);
150 EXPORT_SYMBOL(__vmalloc
);
152 void *__vmalloc_node_range(unsigned long size
, unsigned long align
,
153 unsigned long start
, unsigned long end
, gfp_t gfp_mask
,
154 pgprot_t prot
, unsigned long vm_flags
, int node
,
157 return __vmalloc(size
, gfp_mask
);
160 void *__vmalloc_node(unsigned long size
, unsigned long align
, gfp_t gfp_mask
,
161 int node
, const void *caller
)
163 return __vmalloc(size
, gfp_mask
);
166 static void *__vmalloc_user_flags(unsigned long size
, gfp_t flags
)
170 ret
= __vmalloc(size
, flags
);
172 struct vm_area_struct
*vma
;
174 mmap_write_lock(current
->mm
);
175 vma
= find_vma(current
->mm
, (unsigned long)ret
);
177 vm_flags_set(vma
, VM_USERMAP
);
178 mmap_write_unlock(current
->mm
);
184 void *vmalloc_user(unsigned long size
)
186 return __vmalloc_user_flags(size
, GFP_KERNEL
| __GFP_ZERO
);
188 EXPORT_SYMBOL(vmalloc_user
);
190 struct page
*vmalloc_to_page(const void *addr
)
192 return virt_to_page(addr
);
194 EXPORT_SYMBOL(vmalloc_to_page
);
196 unsigned long vmalloc_to_pfn(const void *addr
)
198 return page_to_pfn(virt_to_page(addr
));
200 EXPORT_SYMBOL(vmalloc_to_pfn
);
202 long vread_iter(struct iov_iter
*iter
, const char *addr
, size_t count
)
204 /* Don't allow overflow */
205 if ((unsigned long) addr
+ count
< count
)
206 count
= -(unsigned long) addr
;
208 return copy_to_iter(addr
, count
, iter
);
212 * vmalloc - allocate virtually contiguous memory
214 * @size: allocation size
216 * Allocate enough pages to cover @size from the page level
217 * allocator and map them into contiguous kernel virtual space.
219 * For tight control over page level allocator and protection flags
220 * use __vmalloc() instead.
222 void *vmalloc(unsigned long size
)
224 return __vmalloc(size
, GFP_KERNEL
);
226 EXPORT_SYMBOL(vmalloc
);
228 void *vmalloc_huge(unsigned long size
, gfp_t gfp_mask
) __weak
__alias(__vmalloc
);
231 * vzalloc - allocate virtually contiguous memory with zero fill
233 * @size: allocation size
235 * Allocate enough pages to cover @size from the page level
236 * allocator and map them into contiguous kernel virtual space.
237 * The memory allocated is set to zero.
239 * For tight control over page level allocator and protection flags
240 * use __vmalloc() instead.
242 void *vzalloc(unsigned long size
)
244 return __vmalloc(size
, GFP_KERNEL
| __GFP_ZERO
);
246 EXPORT_SYMBOL(vzalloc
);
249 * vmalloc_node - allocate memory on a specific node
250 * @size: allocation size
253 * Allocate enough pages to cover @size from the page level
254 * allocator and map them into contiguous kernel virtual space.
256 * For tight control over page level allocator and protection flags
257 * use __vmalloc() instead.
259 void *vmalloc_node(unsigned long size
, int node
)
261 return vmalloc(size
);
263 EXPORT_SYMBOL(vmalloc_node
);
266 * vzalloc_node - allocate memory on a specific node with zero fill
267 * @size: allocation size
270 * Allocate enough pages to cover @size from the page level
271 * allocator and map them into contiguous kernel virtual space.
272 * The memory allocated is set to zero.
274 * For tight control over page level allocator and protection flags
275 * use __vmalloc() instead.
277 void *vzalloc_node(unsigned long size
, int node
)
279 return vzalloc(size
);
281 EXPORT_SYMBOL(vzalloc_node
);
284 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
285 * @size: allocation size
287 * Allocate enough 32bit PA addressable pages to cover @size from the
288 * page level allocator and map them into contiguous kernel virtual space.
290 void *vmalloc_32(unsigned long size
)
292 return __vmalloc(size
, GFP_KERNEL
);
294 EXPORT_SYMBOL(vmalloc_32
);
297 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
298 * @size: allocation size
300 * The resulting memory area is 32bit addressable and zeroed so it can be
301 * mapped to userspace without leaking data.
303 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
304 * remap_vmalloc_range() are permissible.
306 void *vmalloc_32_user(unsigned long size
)
309 * We'll have to sort out the ZONE_DMA bits for 64-bit,
310 * but for now this can simply use vmalloc_user() directly.
312 return vmalloc_user(size
);
314 EXPORT_SYMBOL(vmalloc_32_user
);
316 void *vmap(struct page
**pages
, unsigned int count
, unsigned long flags
, pgprot_t prot
)
323 void vunmap(const void *addr
)
327 EXPORT_SYMBOL(vunmap
);
329 void *vm_map_ram(struct page
**pages
, unsigned int count
, int node
)
334 EXPORT_SYMBOL(vm_map_ram
);
336 void vm_unmap_ram(const void *mem
, unsigned int count
)
340 EXPORT_SYMBOL(vm_unmap_ram
);
342 void vm_unmap_aliases(void)
345 EXPORT_SYMBOL_GPL(vm_unmap_aliases
);
347 void free_vm_area(struct vm_struct
*area
)
351 EXPORT_SYMBOL_GPL(free_vm_area
);
353 int vm_insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
358 EXPORT_SYMBOL(vm_insert_page
);
360 int vm_map_pages(struct vm_area_struct
*vma
, struct page
**pages
,
365 EXPORT_SYMBOL(vm_map_pages
);
367 int vm_map_pages_zero(struct vm_area_struct
*vma
, struct page
**pages
,
372 EXPORT_SYMBOL(vm_map_pages_zero
);
375 * sys_brk() for the most part doesn't need the global kernel
376 * lock, except when an application is doing something nasty
377 * like trying to un-brk an area that has already been mapped
378 * to a regular file. in this case, the unmapping will need
379 * to invoke file system routines that need the global lock.
381 SYSCALL_DEFINE1(brk
, unsigned long, brk
)
383 struct mm_struct
*mm
= current
->mm
;
385 if (brk
< mm
->start_brk
|| brk
> mm
->context
.end_brk
)
392 * Always allow shrinking brk
394 if (brk
<= mm
->brk
) {
400 * Ok, looks good - let it rip.
402 flush_icache_user_range(mm
->brk
, brk
);
403 return mm
->brk
= brk
;
407 * initialise the percpu counter for VM and region record slabs
409 void __init
mmap_init(void)
413 ret
= percpu_counter_init(&vm_committed_as
, 0, GFP_KERNEL
);
415 vm_region_jar
= KMEM_CACHE(vm_region
, SLAB_PANIC
|SLAB_ACCOUNT
);
419 * validate the region tree
420 * - the caller must hold the region lock
422 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
423 static noinline
void validate_nommu_regions(void)
425 struct vm_region
*region
, *last
;
426 struct rb_node
*p
, *lastp
;
428 lastp
= rb_first(&nommu_region_tree
);
432 last
= rb_entry(lastp
, struct vm_region
, vm_rb
);
433 BUG_ON(last
->vm_end
<= last
->vm_start
);
434 BUG_ON(last
->vm_top
< last
->vm_end
);
436 while ((p
= rb_next(lastp
))) {
437 region
= rb_entry(p
, struct vm_region
, vm_rb
);
438 last
= rb_entry(lastp
, struct vm_region
, vm_rb
);
440 BUG_ON(region
->vm_end
<= region
->vm_start
);
441 BUG_ON(region
->vm_top
< region
->vm_end
);
442 BUG_ON(region
->vm_start
< last
->vm_top
);
448 static void validate_nommu_regions(void)
454 * add a region into the global tree
456 static void add_nommu_region(struct vm_region
*region
)
458 struct vm_region
*pregion
;
459 struct rb_node
**p
, *parent
;
461 validate_nommu_regions();
464 p
= &nommu_region_tree
.rb_node
;
467 pregion
= rb_entry(parent
, struct vm_region
, vm_rb
);
468 if (region
->vm_start
< pregion
->vm_start
)
470 else if (region
->vm_start
> pregion
->vm_start
)
472 else if (pregion
== region
)
478 rb_link_node(®ion
->vm_rb
, parent
, p
);
479 rb_insert_color(®ion
->vm_rb
, &nommu_region_tree
);
481 validate_nommu_regions();
485 * delete a region from the global tree
487 static void delete_nommu_region(struct vm_region
*region
)
489 BUG_ON(!nommu_region_tree
.rb_node
);
491 validate_nommu_regions();
492 rb_erase(®ion
->vm_rb
, &nommu_region_tree
);
493 validate_nommu_regions();
497 * free a contiguous series of pages
499 static void free_page_series(unsigned long from
, unsigned long to
)
501 for (; from
< to
; from
+= PAGE_SIZE
) {
502 struct page
*page
= virt_to_page((void *)from
);
504 atomic_long_dec(&mmap_pages_allocated
);
510 * release a reference to a region
511 * - the caller must hold the region semaphore for writing, which this releases
512 * - the region may not have been added to the tree yet, in which case vm_top
513 * will equal vm_start
515 static void __put_nommu_region(struct vm_region
*region
)
516 __releases(nommu_region_sem
)
518 BUG_ON(!nommu_region_tree
.rb_node
);
520 if (--region
->vm_usage
== 0) {
521 if (region
->vm_top
> region
->vm_start
)
522 delete_nommu_region(region
);
523 up_write(&nommu_region_sem
);
526 fput(region
->vm_file
);
528 /* IO memory and memory shared directly out of the pagecache
529 * from ramfs/tmpfs mustn't be released here */
530 if (region
->vm_flags
& VM_MAPPED_COPY
)
531 free_page_series(region
->vm_start
, region
->vm_top
);
532 kmem_cache_free(vm_region_jar
, region
);
534 up_write(&nommu_region_sem
);
539 * release a reference to a region
541 static void put_nommu_region(struct vm_region
*region
)
543 down_write(&nommu_region_sem
);
544 __put_nommu_region(region
);
547 static void setup_vma_to_mm(struct vm_area_struct
*vma
, struct mm_struct
*mm
)
551 /* add the VMA to the mapping */
553 struct address_space
*mapping
= vma
->vm_file
->f_mapping
;
555 i_mmap_lock_write(mapping
);
556 flush_dcache_mmap_lock(mapping
);
557 vma_interval_tree_insert(vma
, &mapping
->i_mmap
);
558 flush_dcache_mmap_unlock(mapping
);
559 i_mmap_unlock_write(mapping
);
563 static void cleanup_vma_from_mm(struct vm_area_struct
*vma
)
565 vma
->vm_mm
->map_count
--;
566 /* remove the VMA from the mapping */
568 struct address_space
*mapping
;
569 mapping
= vma
->vm_file
->f_mapping
;
571 i_mmap_lock_write(mapping
);
572 flush_dcache_mmap_lock(mapping
);
573 vma_interval_tree_remove(vma
, &mapping
->i_mmap
);
574 flush_dcache_mmap_unlock(mapping
);
575 i_mmap_unlock_write(mapping
);
580 * delete a VMA from its owning mm_struct and address space
582 static int delete_vma_from_mm(struct vm_area_struct
*vma
)
584 VMA_ITERATOR(vmi
, vma
->vm_mm
, vma
->vm_start
);
586 if (vma_iter_prealloc(&vmi
)) {
587 pr_warn("Allocation of vma tree for process %d failed\n",
591 cleanup_vma_from_mm(vma
);
593 /* remove from the MM's tree and list */
594 vma_iter_clear(&vmi
, vma
->vm_start
, vma
->vm_end
);
598 * destroy a VMA record
600 static void delete_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
602 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
603 vma
->vm_ops
->close(vma
);
606 put_nommu_region(vma
->vm_region
);
610 struct vm_area_struct
*find_vma_intersection(struct mm_struct
*mm
,
611 unsigned long start_addr
,
612 unsigned long end_addr
)
614 unsigned long index
= start_addr
;
616 mmap_assert_locked(mm
);
617 return mt_find(&mm
->mm_mt
, &index
, end_addr
- 1);
619 EXPORT_SYMBOL(find_vma_intersection
);
622 * look up the first VMA in which addr resides, NULL if none
623 * - should be called with mm->mmap_lock at least held readlocked
625 struct vm_area_struct
*find_vma(struct mm_struct
*mm
, unsigned long addr
)
627 VMA_ITERATOR(vmi
, mm
, addr
);
629 return vma_iter_load(&vmi
);
631 EXPORT_SYMBOL(find_vma
);
635 * - we don't extend stack VMAs under NOMMU conditions
637 struct vm_area_struct
*find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
639 return find_vma(mm
, addr
);
643 * expand a stack to a given address
644 * - not supported under NOMMU conditions
646 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
652 * look up the first VMA exactly that exactly matches addr
653 * - should be called with mm->mmap_lock at least held readlocked
655 static struct vm_area_struct
*find_vma_exact(struct mm_struct
*mm
,
659 struct vm_area_struct
*vma
;
660 unsigned long end
= addr
+ len
;
661 VMA_ITERATOR(vmi
, mm
, addr
);
663 vma
= vma_iter_load(&vmi
);
666 if (vma
->vm_start
!= addr
)
668 if (vma
->vm_end
!= end
)
675 * determine whether a mapping should be permitted and, if so, what sort of
676 * mapping we're capable of supporting
678 static int validate_mmap_request(struct file
*file
,
684 unsigned long *_capabilities
)
686 unsigned long capabilities
, rlen
;
689 /* do the simple checks first */
690 if (flags
& MAP_FIXED
)
693 if ((flags
& MAP_TYPE
) != MAP_PRIVATE
&&
694 (flags
& MAP_TYPE
) != MAP_SHARED
)
700 /* Careful about overflows.. */
701 rlen
= PAGE_ALIGN(len
);
702 if (!rlen
|| rlen
> TASK_SIZE
)
705 /* offset overflow? */
706 if ((pgoff
+ (rlen
>> PAGE_SHIFT
)) < pgoff
)
710 /* files must support mmap */
711 if (!file
->f_op
->mmap
)
714 /* work out if what we've got could possibly be shared
715 * - we support chardevs that provide their own "memory"
716 * - we support files/blockdevs that are memory backed
718 if (file
->f_op
->mmap_capabilities
) {
719 capabilities
= file
->f_op
->mmap_capabilities(file
);
721 /* no explicit capabilities set, so assume some
723 switch (file_inode(file
)->i_mode
& S_IFMT
) {
726 capabilities
= NOMMU_MAP_COPY
;
741 /* eliminate any capabilities that we can't support on this
743 if (!file
->f_op
->get_unmapped_area
)
744 capabilities
&= ~NOMMU_MAP_DIRECT
;
745 if (!(file
->f_mode
& FMODE_CAN_READ
))
746 capabilities
&= ~NOMMU_MAP_COPY
;
748 /* The file shall have been opened with read permission. */
749 if (!(file
->f_mode
& FMODE_READ
))
752 if (flags
& MAP_SHARED
) {
753 /* do checks for writing, appending and locking */
754 if ((prot
& PROT_WRITE
) &&
755 !(file
->f_mode
& FMODE_WRITE
))
758 if (IS_APPEND(file_inode(file
)) &&
759 (file
->f_mode
& FMODE_WRITE
))
762 if (!(capabilities
& NOMMU_MAP_DIRECT
))
765 /* we mustn't privatise shared mappings */
766 capabilities
&= ~NOMMU_MAP_COPY
;
768 /* we're going to read the file into private memory we
770 if (!(capabilities
& NOMMU_MAP_COPY
))
773 /* we don't permit a private writable mapping to be
774 * shared with the backing device */
775 if (prot
& PROT_WRITE
)
776 capabilities
&= ~NOMMU_MAP_DIRECT
;
779 if (capabilities
& NOMMU_MAP_DIRECT
) {
780 if (((prot
& PROT_READ
) && !(capabilities
& NOMMU_MAP_READ
)) ||
781 ((prot
& PROT_WRITE
) && !(capabilities
& NOMMU_MAP_WRITE
)) ||
782 ((prot
& PROT_EXEC
) && !(capabilities
& NOMMU_MAP_EXEC
))
784 capabilities
&= ~NOMMU_MAP_DIRECT
;
785 if (flags
& MAP_SHARED
) {
786 pr_warn("MAP_SHARED not completely supported on !MMU\n");
792 /* handle executable mappings and implied executable
794 if (path_noexec(&file
->f_path
)) {
795 if (prot
& PROT_EXEC
)
797 } else if ((prot
& PROT_READ
) && !(prot
& PROT_EXEC
)) {
798 /* handle implication of PROT_EXEC by PROT_READ */
799 if (current
->personality
& READ_IMPLIES_EXEC
) {
800 if (capabilities
& NOMMU_MAP_EXEC
)
803 } else if ((prot
& PROT_READ
) &&
804 (prot
& PROT_EXEC
) &&
805 !(capabilities
& NOMMU_MAP_EXEC
)
807 /* backing file is not executable, try to copy */
808 capabilities
&= ~NOMMU_MAP_DIRECT
;
811 /* anonymous mappings are always memory backed and can be
814 capabilities
= NOMMU_MAP_COPY
;
816 /* handle PROT_EXEC implication by PROT_READ */
817 if ((prot
& PROT_READ
) &&
818 (current
->personality
& READ_IMPLIES_EXEC
))
822 /* allow the security API to have its say */
823 ret
= security_mmap_addr(addr
);
828 *_capabilities
= capabilities
;
833 * we've determined that we can make the mapping, now translate what we
834 * now know into VMA flags
836 static unsigned long determine_vm_flags(struct file
*file
,
839 unsigned long capabilities
)
841 unsigned long vm_flags
;
843 vm_flags
= calc_vm_prot_bits(prot
, 0) | calc_vm_flag_bits(flags
);
847 * MAP_ANONYMOUS. MAP_SHARED is mapped to MAP_PRIVATE, because
848 * there is no fork().
850 vm_flags
|= VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
851 } else if (flags
& MAP_PRIVATE
) {
852 /* MAP_PRIVATE file mapping */
853 if (capabilities
& NOMMU_MAP_DIRECT
)
854 vm_flags
|= (capabilities
& NOMMU_VMFLAGS
);
856 vm_flags
|= VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
858 if (!(prot
& PROT_WRITE
) && !current
->ptrace
)
860 * R/O private file mapping which cannot be used to
861 * modify memory, especially also not via active ptrace
862 * (e.g., set breakpoints) or later by upgrading
863 * permissions (no mprotect()). We can try overlaying
864 * the file mapping, which will work e.g., on chardevs,
865 * ramfs/tmpfs/shmfs and romfs/cramf.
867 vm_flags
|= VM_MAYOVERLAY
;
869 /* MAP_SHARED file mapping: NOMMU_MAP_DIRECT is set. */
870 vm_flags
|= VM_SHARED
| VM_MAYSHARE
|
871 (capabilities
& NOMMU_VMFLAGS
);
878 * set up a shared mapping on a file (the driver or filesystem provides and
881 static int do_mmap_shared_file(struct vm_area_struct
*vma
)
885 ret
= call_mmap(vma
->vm_file
, vma
);
887 vma
->vm_region
->vm_top
= vma
->vm_region
->vm_end
;
893 /* getting -ENOSYS indicates that direct mmap isn't possible (as
894 * opposed to tried but failed) so we can only give a suitable error as
895 * it's not possible to make a private copy if MAP_SHARED was given */
900 * set up a private mapping or an anonymous shared mapping
902 static int do_mmap_private(struct vm_area_struct
*vma
,
903 struct vm_region
*region
,
905 unsigned long capabilities
)
907 unsigned long total
, point
;
912 * Invoke the file's mapping function so that it can keep track of
913 * shared mappings on devices or memory. VM_MAYOVERLAY will be set if
914 * it may attempt to share, which will make is_nommu_shared_mapping()
917 if (capabilities
& NOMMU_MAP_DIRECT
) {
918 ret
= call_mmap(vma
->vm_file
, vma
);
919 /* shouldn't return success if we're not sharing */
920 if (WARN_ON_ONCE(!is_nommu_shared_mapping(vma
->vm_flags
)))
923 vma
->vm_region
->vm_top
= vma
->vm_region
->vm_end
;
929 /* getting an ENOSYS error indicates that direct mmap isn't
930 * possible (as opposed to tried but failed) so we'll try to
931 * make a private copy of the data and map that instead */
935 /* allocate some memory to hold the mapping
936 * - note that this may not return a page-aligned address if the object
937 * we're allocating is smaller than a page
939 order
= get_order(len
);
941 point
= len
>> PAGE_SHIFT
;
943 /* we don't want to allocate a power-of-2 sized page set */
944 if (sysctl_nr_trim_pages
&& total
- point
>= sysctl_nr_trim_pages
)
947 base
= alloc_pages_exact(total
<< PAGE_SHIFT
, GFP_KERNEL
);
951 atomic_long_add(total
, &mmap_pages_allocated
);
953 vm_flags_set(vma
, VM_MAPPED_COPY
);
954 region
->vm_flags
= vma
->vm_flags
;
955 region
->vm_start
= (unsigned long) base
;
956 region
->vm_end
= region
->vm_start
+ len
;
957 region
->vm_top
= region
->vm_start
+ (total
<< PAGE_SHIFT
);
959 vma
->vm_start
= region
->vm_start
;
960 vma
->vm_end
= region
->vm_start
+ len
;
963 /* read the contents of a file into the copy */
966 fpos
= vma
->vm_pgoff
;
969 ret
= kernel_read(vma
->vm_file
, base
, len
, &fpos
);
973 /* clear the last little bit */
975 memset(base
+ ret
, 0, len
- ret
);
978 vma_set_anonymous(vma
);
984 free_page_series(region
->vm_start
, region
->vm_top
);
985 region
->vm_start
= vma
->vm_start
= 0;
986 region
->vm_end
= vma
->vm_end
= 0;
991 pr_err("Allocation of length %lu from process %d (%s) failed\n",
992 len
, current
->pid
, current
->comm
);
993 show_free_areas(0, NULL
);
998 * handle mapping creation for uClinux
1000 unsigned long do_mmap(struct file
*file
,
1004 unsigned long flags
,
1005 unsigned long pgoff
,
1006 unsigned long *populate
,
1007 struct list_head
*uf
)
1009 struct vm_area_struct
*vma
;
1010 struct vm_region
*region
;
1012 vm_flags_t vm_flags
;
1013 unsigned long capabilities
, result
;
1015 VMA_ITERATOR(vmi
, current
->mm
, 0);
1019 /* decide whether we should attempt the mapping, and if so what sort of
1021 ret
= validate_mmap_request(file
, addr
, len
, prot
, flags
, pgoff
,
1026 /* we ignore the address hint */
1028 len
= PAGE_ALIGN(len
);
1030 /* we've determined that we can make the mapping, now translate what we
1031 * now know into VMA flags */
1032 vm_flags
= determine_vm_flags(file
, prot
, flags
, capabilities
);
1035 /* we're going to need to record the mapping */
1036 region
= kmem_cache_zalloc(vm_region_jar
, GFP_KERNEL
);
1038 goto error_getting_region
;
1040 vma
= vm_area_alloc(current
->mm
);
1042 goto error_getting_vma
;
1044 if (vma_iter_prealloc(&vmi
))
1045 goto error_vma_iter_prealloc
;
1047 region
->vm_usage
= 1;
1048 region
->vm_flags
= vm_flags
;
1049 region
->vm_pgoff
= pgoff
;
1051 vm_flags_init(vma
, vm_flags
);
1052 vma
->vm_pgoff
= pgoff
;
1055 region
->vm_file
= get_file(file
);
1056 vma
->vm_file
= get_file(file
);
1059 down_write(&nommu_region_sem
);
1061 /* if we want to share, we need to check for regions created by other
1062 * mmap() calls that overlap with our proposed mapping
1063 * - we can only share with a superset match on most regular files
1064 * - shared mappings on character devices and memory backed files are
1065 * permitted to overlap inexactly as far as we are concerned for in
1066 * these cases, sharing is handled in the driver or filesystem rather
1069 if (is_nommu_shared_mapping(vm_flags
)) {
1070 struct vm_region
*pregion
;
1071 unsigned long pglen
, rpglen
, pgend
, rpgend
, start
;
1073 pglen
= (len
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1074 pgend
= pgoff
+ pglen
;
1076 for (rb
= rb_first(&nommu_region_tree
); rb
; rb
= rb_next(rb
)) {
1077 pregion
= rb_entry(rb
, struct vm_region
, vm_rb
);
1079 if (!is_nommu_shared_mapping(pregion
->vm_flags
))
1082 /* search for overlapping mappings on the same file */
1083 if (file_inode(pregion
->vm_file
) !=
1087 if (pregion
->vm_pgoff
>= pgend
)
1090 rpglen
= pregion
->vm_end
- pregion
->vm_start
;
1091 rpglen
= (rpglen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1092 rpgend
= pregion
->vm_pgoff
+ rpglen
;
1093 if (pgoff
>= rpgend
)
1096 /* handle inexactly overlapping matches between
1098 if ((pregion
->vm_pgoff
!= pgoff
|| rpglen
!= pglen
) &&
1099 !(pgoff
>= pregion
->vm_pgoff
&& pgend
<= rpgend
)) {
1100 /* new mapping is not a subset of the region */
1101 if (!(capabilities
& NOMMU_MAP_DIRECT
))
1102 goto sharing_violation
;
1106 /* we've found a region we can share */
1107 pregion
->vm_usage
++;
1108 vma
->vm_region
= pregion
;
1109 start
= pregion
->vm_start
;
1110 start
+= (pgoff
- pregion
->vm_pgoff
) << PAGE_SHIFT
;
1111 vma
->vm_start
= start
;
1112 vma
->vm_end
= start
+ len
;
1114 if (pregion
->vm_flags
& VM_MAPPED_COPY
)
1115 vm_flags_set(vma
, VM_MAPPED_COPY
);
1117 ret
= do_mmap_shared_file(vma
);
1119 vma
->vm_region
= NULL
;
1122 pregion
->vm_usage
--;
1124 goto error_just_free
;
1127 fput(region
->vm_file
);
1128 kmem_cache_free(vm_region_jar
, region
);
1134 /* obtain the address at which to make a shared mapping
1135 * - this is the hook for quasi-memory character devices to
1136 * tell us the location of a shared mapping
1138 if (capabilities
& NOMMU_MAP_DIRECT
) {
1139 addr
= file
->f_op
->get_unmapped_area(file
, addr
, len
,
1141 if (IS_ERR_VALUE(addr
)) {
1144 goto error_just_free
;
1146 /* the driver refused to tell us where to site
1147 * the mapping so we'll have to attempt to copy
1150 if (!(capabilities
& NOMMU_MAP_COPY
))
1151 goto error_just_free
;
1153 capabilities
&= ~NOMMU_MAP_DIRECT
;
1155 vma
->vm_start
= region
->vm_start
= addr
;
1156 vma
->vm_end
= region
->vm_end
= addr
+ len
;
1161 vma
->vm_region
= region
;
1163 /* set up the mapping
1164 * - the region is filled in if NOMMU_MAP_DIRECT is still set
1166 if (file
&& vma
->vm_flags
& VM_SHARED
)
1167 ret
= do_mmap_shared_file(vma
);
1169 ret
= do_mmap_private(vma
, region
, len
, capabilities
);
1171 goto error_just_free
;
1172 add_nommu_region(region
);
1174 /* clear anonymous mappings that don't ask for uninitialized data */
1175 if (!vma
->vm_file
&&
1176 (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED
) ||
1177 !(flags
& MAP_UNINITIALIZED
)))
1178 memset((void *)region
->vm_start
, 0,
1179 region
->vm_end
- region
->vm_start
);
1181 /* okay... we have a mapping; now we have to register it */
1182 result
= vma
->vm_start
;
1184 current
->mm
->total_vm
+= len
>> PAGE_SHIFT
;
1187 BUG_ON(!vma
->vm_region
);
1188 setup_vma_to_mm(vma
, current
->mm
);
1189 current
->mm
->map_count
++;
1190 /* add the VMA to the tree */
1191 vma_iter_store(&vmi
, vma
);
1193 /* we flush the region from the icache only when the first executable
1194 * mapping of it is made */
1195 if (vma
->vm_flags
& VM_EXEC
&& !region
->vm_icache_flushed
) {
1196 flush_icache_user_range(region
->vm_start
, region
->vm_end
);
1197 region
->vm_icache_flushed
= true;
1200 up_write(&nommu_region_sem
);
1205 up_write(&nommu_region_sem
);
1207 vma_iter_free(&vmi
);
1208 if (region
->vm_file
)
1209 fput(region
->vm_file
);
1210 kmem_cache_free(vm_region_jar
, region
);
1217 up_write(&nommu_region_sem
);
1218 pr_warn("Attempt to share mismatched mappings\n");
1223 kmem_cache_free(vm_region_jar
, region
);
1224 pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
1226 show_free_areas(0, NULL
);
1229 error_getting_region
:
1230 pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
1232 show_free_areas(0, NULL
);
1235 error_vma_iter_prealloc
:
1236 kmem_cache_free(vm_region_jar
, region
);
1238 pr_warn("Allocation of vma tree for process %d failed\n", current
->pid
);
1239 show_free_areas(0, NULL
);
1244 unsigned long ksys_mmap_pgoff(unsigned long addr
, unsigned long len
,
1245 unsigned long prot
, unsigned long flags
,
1246 unsigned long fd
, unsigned long pgoff
)
1248 struct file
*file
= NULL
;
1249 unsigned long retval
= -EBADF
;
1251 audit_mmap_fd(fd
, flags
);
1252 if (!(flags
& MAP_ANONYMOUS
)) {
1258 retval
= vm_mmap_pgoff(file
, addr
, len
, prot
, flags
, pgoff
);
1266 SYSCALL_DEFINE6(mmap_pgoff
, unsigned long, addr
, unsigned long, len
,
1267 unsigned long, prot
, unsigned long, flags
,
1268 unsigned long, fd
, unsigned long, pgoff
)
1270 return ksys_mmap_pgoff(addr
, len
, prot
, flags
, fd
, pgoff
);
1273 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1274 struct mmap_arg_struct
{
1278 unsigned long flags
;
1280 unsigned long offset
;
1283 SYSCALL_DEFINE1(old_mmap
, struct mmap_arg_struct __user
*, arg
)
1285 struct mmap_arg_struct a
;
1287 if (copy_from_user(&a
, arg
, sizeof(a
)))
1289 if (offset_in_page(a
.offset
))
1292 return ksys_mmap_pgoff(a
.addr
, a
.len
, a
.prot
, a
.flags
, a
.fd
,
1293 a
.offset
>> PAGE_SHIFT
);
1295 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1298 * split a vma into two pieces at address 'addr', a new vma is allocated either
1299 * for the first part or the tail.
1301 int split_vma(struct vma_iterator
*vmi
, struct vm_area_struct
*vma
,
1302 unsigned long addr
, int new_below
)
1304 struct vm_area_struct
*new;
1305 struct vm_region
*region
;
1306 unsigned long npages
;
1307 struct mm_struct
*mm
;
1309 /* we're only permitted to split anonymous regions (these should have
1310 * only a single usage on the region) */
1315 if (mm
->map_count
>= sysctl_max_map_count
)
1318 region
= kmem_cache_alloc(vm_region_jar
, GFP_KERNEL
);
1322 new = vm_area_dup(vma
);
1326 if (vma_iter_prealloc(vmi
)) {
1327 pr_warn("Allocation of vma tree for process %d failed\n",
1329 goto err_vmi_preallocate
;
1332 /* most fields are the same, copy all, and then fixup */
1333 *region
= *vma
->vm_region
;
1334 new->vm_region
= region
;
1336 npages
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
1339 region
->vm_top
= region
->vm_end
= new->vm_end
= addr
;
1341 region
->vm_start
= new->vm_start
= addr
;
1342 region
->vm_pgoff
= new->vm_pgoff
+= npages
;
1345 if (new->vm_ops
&& new->vm_ops
->open
)
1346 new->vm_ops
->open(new);
1348 down_write(&nommu_region_sem
);
1349 delete_nommu_region(vma
->vm_region
);
1351 vma
->vm_region
->vm_start
= vma
->vm_start
= addr
;
1352 vma
->vm_region
->vm_pgoff
= vma
->vm_pgoff
+= npages
;
1354 vma
->vm_region
->vm_end
= vma
->vm_end
= addr
;
1355 vma
->vm_region
->vm_top
= addr
;
1357 add_nommu_region(vma
->vm_region
);
1358 add_nommu_region(new->vm_region
);
1359 up_write(&nommu_region_sem
);
1361 setup_vma_to_mm(vma
, mm
);
1362 setup_vma_to_mm(new, mm
);
1363 vma_iter_store(vmi
, new);
1367 err_vmi_preallocate
:
1370 kmem_cache_free(vm_region_jar
, region
);
1375 * shrink a VMA by removing the specified chunk from either the beginning or
1378 static int vmi_shrink_vma(struct vma_iterator
*vmi
,
1379 struct vm_area_struct
*vma
,
1380 unsigned long from
, unsigned long to
)
1382 struct vm_region
*region
;
1384 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1386 if (vma_iter_prealloc(vmi
)) {
1387 pr_warn("Allocation of vma tree for process %d failed\n",
1392 if (from
> vma
->vm_start
) {
1393 vma_iter_clear(vmi
, from
, vma
->vm_end
);
1396 vma_iter_clear(vmi
, vma
->vm_start
, to
);
1400 /* cut the backing region down to size */
1401 region
= vma
->vm_region
;
1402 BUG_ON(region
->vm_usage
!= 1);
1404 down_write(&nommu_region_sem
);
1405 delete_nommu_region(region
);
1406 if (from
> region
->vm_start
) {
1407 to
= region
->vm_top
;
1408 region
->vm_top
= region
->vm_end
= from
;
1410 region
->vm_start
= to
;
1412 add_nommu_region(region
);
1413 up_write(&nommu_region_sem
);
1415 free_page_series(from
, to
);
1421 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1422 * VMA, though it need not cover the whole VMA
1424 int do_munmap(struct mm_struct
*mm
, unsigned long start
, size_t len
, struct list_head
*uf
)
1426 VMA_ITERATOR(vmi
, mm
, start
);
1427 struct vm_area_struct
*vma
;
1431 len
= PAGE_ALIGN(len
);
1437 /* find the first potentially overlapping VMA */
1438 vma
= vma_find(&vmi
, end
);
1442 pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
1443 current
->pid
, current
->comm
,
1444 start
, start
+ len
- 1);
1450 /* we're allowed to split an anonymous VMA but not a file-backed one */
1453 if (start
> vma
->vm_start
)
1455 if (end
== vma
->vm_end
)
1456 goto erase_whole_vma
;
1457 vma
= vma_find(&vmi
, end
);
1461 /* the chunk must be a subset of the VMA found */
1462 if (start
== vma
->vm_start
&& end
== vma
->vm_end
)
1463 goto erase_whole_vma
;
1464 if (start
< vma
->vm_start
|| end
> vma
->vm_end
)
1466 if (offset_in_page(start
))
1468 if (end
!= vma
->vm_end
&& offset_in_page(end
))
1470 if (start
!= vma
->vm_start
&& end
!= vma
->vm_end
) {
1471 ret
= split_vma(&vmi
, vma
, start
, 1);
1475 return vmi_shrink_vma(&vmi
, vma
, start
, end
);
1479 if (delete_vma_from_mm(vma
))
1482 delete_vma(mm
, vma
);
1486 int vm_munmap(unsigned long addr
, size_t len
)
1488 struct mm_struct
*mm
= current
->mm
;
1491 mmap_write_lock(mm
);
1492 ret
= do_munmap(mm
, addr
, len
, NULL
);
1493 mmap_write_unlock(mm
);
1496 EXPORT_SYMBOL(vm_munmap
);
1498 SYSCALL_DEFINE2(munmap
, unsigned long, addr
, size_t, len
)
1500 return vm_munmap(addr
, len
);
1504 * release all the mappings made in a process's VM space
1506 void exit_mmap(struct mm_struct
*mm
)
1508 VMA_ITERATOR(vmi
, mm
, 0);
1509 struct vm_area_struct
*vma
;
1517 * Lock the mm to avoid assert complaining even though this is the only
1520 mmap_write_lock(mm
);
1521 for_each_vma(vmi
, vma
) {
1522 cleanup_vma_from_mm(vma
);
1523 delete_vma(mm
, vma
);
1526 __mt_destroy(&mm
->mm_mt
);
1527 mmap_write_unlock(mm
);
1530 int vm_brk(unsigned long addr
, unsigned long len
)
1536 * expand (or shrink) an existing mapping, potentially moving it at the same
1537 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1539 * under NOMMU conditions, we only permit changing a mapping's size, and only
1540 * as long as it stays within the region allocated by do_mmap_private() and the
1541 * block is not shareable
1543 * MREMAP_FIXED is not supported under NOMMU conditions
1545 static unsigned long do_mremap(unsigned long addr
,
1546 unsigned long old_len
, unsigned long new_len
,
1547 unsigned long flags
, unsigned long new_addr
)
1549 struct vm_area_struct
*vma
;
1551 /* insanity checks first */
1552 old_len
= PAGE_ALIGN(old_len
);
1553 new_len
= PAGE_ALIGN(new_len
);
1554 if (old_len
== 0 || new_len
== 0)
1555 return (unsigned long) -EINVAL
;
1557 if (offset_in_page(addr
))
1560 if (flags
& MREMAP_FIXED
&& new_addr
!= addr
)
1561 return (unsigned long) -EINVAL
;
1563 vma
= find_vma_exact(current
->mm
, addr
, old_len
);
1565 return (unsigned long) -EINVAL
;
1567 if (vma
->vm_end
!= vma
->vm_start
+ old_len
)
1568 return (unsigned long) -EFAULT
;
1570 if (is_nommu_shared_mapping(vma
->vm_flags
))
1571 return (unsigned long) -EPERM
;
1573 if (new_len
> vma
->vm_region
->vm_end
- vma
->vm_region
->vm_start
)
1574 return (unsigned long) -ENOMEM
;
1576 /* all checks complete - do it */
1577 vma
->vm_end
= vma
->vm_start
+ new_len
;
1578 return vma
->vm_start
;
1581 SYSCALL_DEFINE5(mremap
, unsigned long, addr
, unsigned long, old_len
,
1582 unsigned long, new_len
, unsigned long, flags
,
1583 unsigned long, new_addr
)
1587 mmap_write_lock(current
->mm
);
1588 ret
= do_mremap(addr
, old_len
, new_len
, flags
, new_addr
);
1589 mmap_write_unlock(current
->mm
);
1593 struct page
*follow_page(struct vm_area_struct
*vma
, unsigned long address
,
1594 unsigned int foll_flags
)
1599 int remap_pfn_range(struct vm_area_struct
*vma
, unsigned long addr
,
1600 unsigned long pfn
, unsigned long size
, pgprot_t prot
)
1602 if (addr
!= (pfn
<< PAGE_SHIFT
))
1605 vm_flags_set(vma
, VM_IO
| VM_PFNMAP
| VM_DONTEXPAND
| VM_DONTDUMP
);
1608 EXPORT_SYMBOL(remap_pfn_range
);
1610 int vm_iomap_memory(struct vm_area_struct
*vma
, phys_addr_t start
, unsigned long len
)
1612 unsigned long pfn
= start
>> PAGE_SHIFT
;
1613 unsigned long vm_len
= vma
->vm_end
- vma
->vm_start
;
1615 pfn
+= vma
->vm_pgoff
;
1616 return io_remap_pfn_range(vma
, vma
->vm_start
, pfn
, vm_len
, vma
->vm_page_prot
);
1618 EXPORT_SYMBOL(vm_iomap_memory
);
1620 int remap_vmalloc_range(struct vm_area_struct
*vma
, void *addr
,
1621 unsigned long pgoff
)
1623 unsigned int size
= vma
->vm_end
- vma
->vm_start
;
1625 if (!(vma
->vm_flags
& VM_USERMAP
))
1628 vma
->vm_start
= (unsigned long)(addr
+ (pgoff
<< PAGE_SHIFT
));
1629 vma
->vm_end
= vma
->vm_start
+ size
;
1633 EXPORT_SYMBOL(remap_vmalloc_range
);
1635 vm_fault_t
filemap_fault(struct vm_fault
*vmf
)
1640 EXPORT_SYMBOL(filemap_fault
);
1642 vm_fault_t
filemap_map_pages(struct vm_fault
*vmf
,
1643 pgoff_t start_pgoff
, pgoff_t end_pgoff
)
1648 EXPORT_SYMBOL(filemap_map_pages
);
1650 int __access_remote_vm(struct mm_struct
*mm
, unsigned long addr
, void *buf
,
1651 int len
, unsigned int gup_flags
)
1653 struct vm_area_struct
*vma
;
1654 int write
= gup_flags
& FOLL_WRITE
;
1656 if (mmap_read_lock_killable(mm
))
1659 /* the access must start within one of the target process's mappings */
1660 vma
= find_vma(mm
, addr
);
1662 /* don't overrun this mapping */
1663 if (addr
+ len
>= vma
->vm_end
)
1664 len
= vma
->vm_end
- addr
;
1666 /* only read or write mappings where it is permitted */
1667 if (write
&& vma
->vm_flags
& VM_MAYWRITE
)
1668 copy_to_user_page(vma
, NULL
, addr
,
1669 (void *) addr
, buf
, len
);
1670 else if (!write
&& vma
->vm_flags
& VM_MAYREAD
)
1671 copy_from_user_page(vma
, NULL
, addr
,
1672 buf
, (void *) addr
, len
);
1679 mmap_read_unlock(mm
);
1685 * access_remote_vm - access another process' address space
1686 * @mm: the mm_struct of the target address space
1687 * @addr: start address to access
1688 * @buf: source or destination buffer
1689 * @len: number of bytes to transfer
1690 * @gup_flags: flags modifying lookup behaviour
1692 * The caller must hold a reference on @mm.
1694 int access_remote_vm(struct mm_struct
*mm
, unsigned long addr
,
1695 void *buf
, int len
, unsigned int gup_flags
)
1697 return __access_remote_vm(mm
, addr
, buf
, len
, gup_flags
);
1701 * Access another process' address space.
1702 * - source/target buffer must be kernel space
1704 int access_process_vm(struct task_struct
*tsk
, unsigned long addr
, void *buf
, int len
,
1705 unsigned int gup_flags
)
1707 struct mm_struct
*mm
;
1709 if (addr
+ len
< addr
)
1712 mm
= get_task_mm(tsk
);
1716 len
= __access_remote_vm(mm
, addr
, buf
, len
, gup_flags
);
1721 EXPORT_SYMBOL_GPL(access_process_vm
);
1724 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1725 * @inode: The inode to check
1726 * @size: The current filesize of the inode
1727 * @newsize: The proposed filesize of the inode
1729 * Check the shared mappings on an inode on behalf of a shrinking truncate to
1730 * make sure that any outstanding VMAs aren't broken and then shrink the
1731 * vm_regions that extend beyond so that do_mmap() doesn't
1732 * automatically grant mappings that are too large.
1734 int nommu_shrink_inode_mappings(struct inode
*inode
, size_t size
,
1737 struct vm_area_struct
*vma
;
1738 struct vm_region
*region
;
1740 size_t r_size
, r_top
;
1742 low
= newsize
>> PAGE_SHIFT
;
1743 high
= (size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1745 down_write(&nommu_region_sem
);
1746 i_mmap_lock_read(inode
->i_mapping
);
1748 /* search for VMAs that fall within the dead zone */
1749 vma_interval_tree_foreach(vma
, &inode
->i_mapping
->i_mmap
, low
, high
) {
1750 /* found one - only interested if it's shared out of the page
1752 if (vma
->vm_flags
& VM_SHARED
) {
1753 i_mmap_unlock_read(inode
->i_mapping
);
1754 up_write(&nommu_region_sem
);
1755 return -ETXTBSY
; /* not quite true, but near enough */
1759 /* reduce any regions that overlap the dead zone - if in existence,
1760 * these will be pointed to by VMAs that don't overlap the dead zone
1762 * we don't check for any regions that start beyond the EOF as there
1765 vma_interval_tree_foreach(vma
, &inode
->i_mapping
->i_mmap
, 0, ULONG_MAX
) {
1766 if (!(vma
->vm_flags
& VM_SHARED
))
1769 region
= vma
->vm_region
;
1770 r_size
= region
->vm_top
- region
->vm_start
;
1771 r_top
= (region
->vm_pgoff
<< PAGE_SHIFT
) + r_size
;
1773 if (r_top
> newsize
) {
1774 region
->vm_top
-= r_top
- newsize
;
1775 if (region
->vm_end
> region
->vm_top
)
1776 region
->vm_end
= region
->vm_top
;
1780 i_mmap_unlock_read(inode
->i_mapping
);
1781 up_write(&nommu_region_sem
);
1786 * Initialise sysctl_user_reserve_kbytes.
1788 * This is intended to prevent a user from starting a single memory hogging
1789 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1792 * The default value is min(3% of free memory, 128MB)
1793 * 128MB is enough to recover with sshd/login, bash, and top/kill.
1795 static int __meminit
init_user_reserve(void)
1797 unsigned long free_kbytes
;
1799 free_kbytes
= global_zone_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
1801 sysctl_user_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 17);
1804 subsys_initcall(init_user_reserve
);
1807 * Initialise sysctl_admin_reserve_kbytes.
1809 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1810 * to log in and kill a memory hogging process.
1812 * Systems with more than 256MB will reserve 8MB, enough to recover
1813 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1814 * only reserve 3% of free pages by default.
1816 static int __meminit
init_admin_reserve(void)
1818 unsigned long free_kbytes
;
1820 free_kbytes
= global_zone_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
1822 sysctl_admin_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 13);
1825 subsys_initcall(init_admin_reserve
);